DEPARTMENT OF THE INTERIOR 

U.S. GEOLOGICAL SURVEY

CATALOG OF THE 

HISTORICALLY ACTIVE VOLCANOES OF ALASKA

by

T.P. Miller ] ,R,G.lv1cGimsey ] ,D.H.Rlchter J ,

J.R. Riehfe ',CJ. Nye 2, M.E. Younf\

andJ.A. Dumoulin ]

'U.S, Geological Survey 

Anchorage, AK 995GS

2AiaskaDsvisonof

Geological and Geophysical Surveys 

Fairbanks, AK 99709

Open File Report 98-582 

1998

Done in cooperation with the

International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) 

and the Catalog of Active Volcanoes of the World (CAVW) Prefect

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial

standards (or with the North American Stratigraphic Code). Any use of trade, product or firm names is for

descriptive purposes only and does not imply endorsement by the U,S. Government
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

TABLE OF CONTENTS

Introduction ..................................................................................................................................................................i

Previous work.............................................................................................................................................................. i

Methodology ........................................................................

Summary of historical volcanic activity.................................................................................................................iv

Historically Active Volcanoes.................................................................................................................................... 1

Mount Wrangell Volcano...........................................................................................................................................3

Mount Spurr ............................................................................................................................................................... 5

Redoubt Volcano ....................................................................................................................................................... 8

Iliamna Volcano.......................................................................................................................................................... 1

Augustine Volcano.................................................................................................................................................... 13

Mt. Katmai, Katmai Caldera ................................................................................................................................... 15

Novarupta ................................................................................................................................................................ 17

Trident Complex...................................................................................................................................................... 19

Mount Mageik ......................................................................................................................................................... 2 0

Mount Martin.............................................................................................................................................................21

Mount Peulik Volcano ............................................................................................................................................. 2 3

Ukinrek Maars ......................................................................................................................................................... 2 5

Chiginagak Volcano .................................................................................................................................................27

Aniakchak Caldera.................................................................................................................................................. 2 9

Mount Veniaminof.....................................................................................................................................................31

Pavlof Volcano......................................................................................................................................................... 3 5

Dutton Volcano........................................................................................................................................................ 3 7

Isanotski Volcano .................................................................................................................................................... 3 9

ShishaldinVolcano...................................................................................................................................................... 41

Fisher Caldera......................................................................................................................................................... 43

Westdahl Volcano ....................................................................................................................................................45

Akutan Volcano ....................................................................................................................................................... 47

Makushin Volcano .....................................................................................................................................................51

Bogoslof Volcano .....................................................................................................................................................5 4

Okmok Volcano ....................................................................................................................................................... 57

Vsevidof Volcano ......................................................................................................................................................61

Kagamil Volcano ..................................................................................................................................................... 6 3

Cleveland Volcano ...................................................................................................................................................6 5

Carlisle Volcano........................................................................................................................................................67

Yunaska Volcano Complex .................................................................................................................................... 6 9

Amukta Volcano ....................................................................................................................................................... 71

Seguam Volcano (Pyre Peak) ................................................................................................................................. 7 3

Korovin Volcano ......................................................................................................................................................75

Kasatochi Volcano................................................................................................................................................... 77

Great Sitkin Volcano............................................................................................................................................... 7 9

Kanaga Volcano ...................................................................................................................................................... 8 2

Tanaga Volcano....................................................................................................................................................... 8 5

Gareloi Volcano........................................................................................................................................................87

Semisopochnoi Volcano (Mount Cerberus) .......................................................................................................... 8 9

Little Sitkin Volcano............................................................................................................................................... 9 3

Kiska Volcano ..........................................................................................................................................................97

References .........................................................^^
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Introduction

Alaska hosts within its borders over 80 major volcanic 

centers that have erupted during Holocene time (< 10,000 

years). At least 29 of these volcanic centers (table 1) had 

historical eruptions and 12 additional volcanic centers may 

have had historical eruptions. Historical in Alaska generally means the period since 1760 when explorers, travelers, and inhabitants kept written records. These 41 

volcanic centers have been the source for >265 eruptions 

reported from Alaska volcanoes.

With the exception of Wrangell volcano, all the 

centers are in, or near, the Aleutian volcanic arc, which 

extends 2500 km from Hayes volcano 145 km west of 

Anchorage in the Alaska-Aleutian Range to Buldir Island 

in the western Aleutian Islands (fig. 1). The volcanic arc, a

This report discusses the location, physiography and 

structure, eruptive history, and geology of those volcanoes 

in Alaska that have experienced one or more eruptions that 

have been recorded in the written history (i.e., in historical 

time). It is part of the group of catalogs entitled Catalogue 

of Active Volcanoes of the World published beginning in 

1951 under the auspices of the International Association of 

Volcanology and Chemistry of the Earth's Interior 

(IAVCEI). A knowledge of the information contained in 

such catalogs aids in understanding the type and scale of 

activity that might be expected during a particular eruption, the hazards the eruption may pose, and even the 

prediction of eruptions. The catalog will thus be of value 

not only to the inhabitants of Alaska but to government 

agencies concerned with emergency response, air traffic

INDEX MAP

OF

HISTORICALLY ACTIVE 

ALASKAN VOLCANOES

BERING SEA

Buildir

Island

v

. 41 52" - I /

40 39 Aleutian Islands

Island y. >/

^> >-// » a* 34 24 23 -"Mcr * t ^j^W' "-

/ :^^ A I * *> , jJarT-' zz <

j GULF OF ALASKA

Atka 

Island

«P ?*\ "I or

30; 0\ 26 ^

Unalaska 

Island

I 158'W

i

PACIFIC OCEAN

200 400 mi

0 200

I i I

400km

1. Wrangell

2. Spurr

3. Redoubt

4. Iliamna

5. Augustine

6. Katmai

7. Novaruota

8. Trident

9. Mageik

10. Martin

11. Peulik

12. Ukinrek

13. Chiginagak

14. Aniakchak

15. Veniaminof

16. Pavlof

17. Dutton

18. Isanotski

19. Shishaldin

20. Fisher

21. Westdahl

22. Akutan

23. Makushin

24. Bogoslof

25. Okmok

26. Vsevidof

27. Kagamil

28. Carlisle

29. Cleveland

30. Yunaska

31. Amukta

32. Seguam

33. Korovin

34. Kasatochi

35. Great Sitkin

36. Kanaga

37. Tanaga

38. Gareloi

39. Cerberus

40. Little Sitkin

41. Kiska

Figure 1. Index map of historically active Alaskan volcanoes.

subduction-related feature associated with underthrusting 

of the Pacific plate beneath the North American plate is 

divided between oceanic island arc and continental margin 

segments, the boundary occurring at about 165° W 

longitude (fig. 1). An additional 7 volcanic centers in the 

Aleutian arc (table 2; fig. 1 A) have active fumarole fields 

but no reported historical eruptions.

operations, and weather, as well as to industry and 

scientists. The combination of the hazard posed by 

volcanic ash to jet aircraft and the heavy use of international air routes located parallel to, and on either side of, 

the Aleutian volcanic arc means that even remote volcanoes in Alaska now pose significant hazards to life and 

property.

Although this report is concerned with historical 

eruptions from Alaskan volcanoes, other volcanoes in
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Alaska have erupted in the past 10,000 years and might 

therefore be expected to erupt again. Several Holocene 

volcanic centers in the Aleutian arc have no reported 

historical activity. Elsewhere in Alaska the Bering Sea 

basalt fields cover large areas of the Yukon Delta, Seward 

Peninsula, and several of the islands of the Bering Sea. 

Holocene centers also occur in the Wrangell Mountains 

and in isolated occurrences in the interior and southeastern 

Alaska. Eruptions from these centers have occurred within 

the past several hundred years but none were transcribed in 

the written record. Moodie and others (1992), however, 

report oral traditions among the Northern Athapaskan 

Indians of the southwestern Yukon Territory that may 

record the second and younger deposition of the White 

River Ash circa A.D. 720. This lobe of the White River 

Ash was deposited during the paroxysmal eruption of 

Churchill volcano in the Wrangell Mountains of eastcentral Alaska (McGimsey and others, 1992; Richter and 

others, 1995).

Acknowledgments: Tom Simkin reviewed this report and has 

been a tireless supporter of the project. Jean Sobolik (UAFGI) 

did an extraordinary job in the electronic preparation of the 

report and Ann Vanderpool ably provided electronic drafting of 

illustrations. Bob Decker provided strong encouragement at the 

beginning and end of the project.

Previous work

The first catalog of volcanic eruptions in Alaska was 

published in the 1840's by the Russian missionary I. 

Veniaminov. This was soon followed by a comprehensive 

chronology presented by C. Grewingk in 1848. The first 

modern listing of active volcanoes in Alaska was published by Robert R. Coats in 1950 who considered 36 

volcanoes in the Aleutian arc to have been active since 

1760. His careful researching of early documents, many of 

which are in Russian or are otherwise difficult to obtain, 

has provided most of the information for eruptions 

reported before 1949. Simkin and others (1981) produced 

their classic Volcanoes of the World, a world-wide 

directory, gazetteer, and chronology of volcanism during 

the past 10,000 years that listed historical Alaskan eruptions through 1980. This work was extended through 1985 

by the Global Volcanism 1975-1985 report by McClelland 

and others (1989) who summarized the first decade of 

reports from the Smithsonian Institution's Scientific Event 

Alert Network (SEAN). Information from these two 

sources was combined in a second edition of Volcanoes of 

the World published in 1994. For ease in identification of 

volcanoes, the Catalog of Active Volcanoes of the World 

(CAVW) number for each volcano is listed in this report. 

Volcanoes of North America, a compilation edited by 

Wood and Kienle (1990), briefly discusses all volcanoes in 

North America younger than 5 million years.

Methodology

Information on historical volcanic eruptions was taken 

from the aforementioned previous compendiums plus 

material from the Smithsonian Institution's Scientific 

Event Alert Network and Bulletin of Volcanic Eruptions, 

other published accounts, and the files of the Alaska 

Volcano Observatory. Information on the geology, composition, form, and structure of the described volcanic 

centers was taken from the most current literature or from 

ongoing studies by the authors.

For the purposes of this catalog, an active volcano is 

defined as one which has experienced a volcanic eruption, 

other than low level ejection of solely steam and gas, in 

historical time. A volcanic eruption is defined (Bates and 

Jackson, 1987, p. 222) as the "ejection of volcanic 

materials (lava, pyroclasts, and volcanic gases) onto the 

Earth's surface...". Although this definition seems clear 

enough, confusion can arise with the volcanic gases part of 

the definition. At least 40 Alaskan volcanoes are venting 

steam and other gases continuously from fumarolic fields 

and often these steam and vapor plumes, which are often 

quite vigorous, are reported as eruptions. To consider such 

activity an eruption removes the value of a catalog such as 

this. Therefore, while large chiefly phreatic events such as 

recorded from Great Sitkin in 1974 are included herein, 

the continuous venting at other volcanoes, such as that 

seen at Mageik volcano in Katmai National Park, is not 

taken as a priori evidence of a historical eruption. Mt. 

Button and Iliamna volcanoes have been included because 

of recent strong seismic swarms.

The historical record extending from 1760 into this 

century is spotty. Most of Alaska, and the Aleutian Islands 

in particular, is remote and sparsely populated; only about 

one quarter of the historically active volcanoes are within 

view of permanent inhabitants and these views are 

frequently obscured by clouds. Early reports of volcanic 

activity largely resulted from the chance passing of 

explorers and traders and many eruptions undoubtedly 

went unnoticed, even during the past century. Uncertainty 

as to what volcano is actually erupting also arises when 

eruptions were, or are, witnessed from a great distance.

Moreover, eyewitness accounts must be closely 

scrutinized to determine whether observers truly witnessed 

an eruption. Eruptive activity has been erroneously 

reported because of a variety of physical phenomena such 

as condensation induced by atmospheric conditions, rock 

exposed by snowmelt, and dust raised by strong winds and 

landslides. For example, ash is often reported falling on 

the southwest end of Kodiak Island and in Shelikof Strait, 

particularly in the fall of the year. Aerial inspections have 

failed to locate any evidence of an eruption on the mainland; instead, the "eruptions" appear to result from strong
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

north winds blowing pumice off the unvegetated pyroclastic flow sheets in the Valley of 10,000 Smokes in Katmai 

National Park. The reporting of steam and condensate 

plumes from fumarolic vents as "smoke" (i.e., an eruption) 

is a vexing problem even today since, under the proper 

meteorological conditions, such plumes can expand to 

heights of a few thousand feet in minutes resulting in 

erroneous eruption reports. Iliamna volcano in Cook Inlet 

is especially subject to such phenomena and several 

reports of eruptions from the volcano are received at the 

Alaska Volcano Observatory each year.

We have therefore chosen to view old reports restricted to "smoke" or "active" with a somewhat jaundiced 

eye. If this is the only report of activity from a volcano (as 

for Amak Island in the Bering Sea) or other collaborating 

information is lacking, we have generally deleted the 

eruption (and in some cases the volcano) from our listing. 

An additional problem arises as to when one eruption ends 

and another begins since it is not unusual for individual 

eruptions to have a quiescent hiatus of weeks to months. 

Generally, if the period of repose can be determined to be 

more than 3-4 months, we have considered the eruptions to 

be separate.

Rock names used in this report follow the recommended IUGS chemical classification of volcanic rocks 

(LeBas and others, 1986) which is based on silica (SiO2 ) 

and total alkali (Na2O+K2O) content. The use of rock 

names from original sources that had no supporting 

chemical data are followed by a citation of the source. No 

chemical analyses of volcanic rocks are included in the 

description of the individual volcanoes. However, plots of 

Na2O+K2O vs. SiO2 and FeO*/MgO vs. SiO2 for over 600 

analyses of Aleutian arc volcanic rocks (most of these 

analyses are from a data base compiled by C.J. Nye, 

Alaska Division of Geological and Geophysical Surveys) 

have been calculated for the arc as a whole and for the 

oceanic and continental segments separately and are 

presented in figs. 2A, 2B, 2C, 3A, 3B, and 3C.

The FeO*/MgO plots distinguish between tholeiitic 

and calc-alkaline magma series rocks (Miyashiro, 1974). 

The eastern continental part of the arc (all volcanoes east 

of and including Westdahl volcano, fig. 1) shows a 

predominance of calc-alkaline over tholeiitic compositions, a reflection of the almost complete dominance of 

calc-alkaline rocks in the eastern third of the arc (Miller 

and Richter, 1994). The western oceanic part shows a more 

equal distribution of the two suites.

In addition, for each volcano where major-element 

chemistry is available, analyses are plotted on Na2O+K2O 

vs. SiO2 and FeO*/MgO vs. SiO2 diagrams and compared 

with analyses from the total data base for that segment of 

the arc (continental or oceanic) in which the volcano 

occurs.

45

SiO2 WT.%

Figure 2A. Figure 2A. Total alkalies-silica (TAS) diagram of 

Aleutian arc volcanic rocks. Discriminant lines and field names 

shown are those recommended by the IUGS (Le Bas and others, 

1986) and apply to all subsequent TAS diagrams in this catalog.

10

9

8

7

6

5

4

3

2

1

0

I

- Basalt

Andesite

Dacite

45 50 55 60 65 70 75 80 

Si02 WT.%

Figure 2B. Total alkalies-silica (TAS) diagram of volcanic rocks 

from continental margin part of Aleutian volcanic arc.

45 50 55 60 65 70 75 80

SiO2 WT.%

Figure 2C. Total alkalies-silica (TAS) diagram of volcanic rocks 

from oceanic island-arc part of Aleutian volcanic arc.

in
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

45 50 55 60 65 70 75 

Si02 WT%

Figure 3A. FeO*/MgO-silica diagram of volcanic rocks from 

entire Aleutian arc.

SiO2 frequency distribution plots (figs. 4A, 4B, 4C) 

are also calculated for the volcanic arc as a whole and for 

the two segments. The eastern, or continental margin, part 

of the arc shows a crudely bell-shaped distribution curve 

centered around a composition of 60 to 61% SiOr The 

western, or oceanic, island arc shows a broader, more 

mafic distribution centered approximately around 54 to 

55% SiO2 .

Geographic names and synonyms are taken from 

Coats (1950), Orth (1967), and U.S. Geological Survey 

quadrangle maps. In the Aleutian Islands, a distinction is 

made between the name of the volcano and the name of 

the island only if more than one volcano on the island has 

been active.

Summary of historical volcanic activity

8

7

6

O 5

O)

P 4

O 

£ 3

2

1

45 50 55 60 65 70 75 

SiO2 WT%

Figure 3B. FeO*/MgO-silica diagram of volcanic rocks from 

continental margin part of Aleutian arc.

8

7

6

& 5 

I 4

<D » 

U_ *

2

1

-5 :' ' .-'-'i?.. ;. rui^i * ' '

45 50 55 60 65 70 75 

SiO2 WT%

Figure 3C. FeO*/MgO-silica diagram of volcanic rocks from 

oceanic island arc part of Aleutian arc.

Forty-one volcanic centers are listed in this catalog. 

Of these, 29 undoubtedly had historical eruptions and 10 

may have had eruptions. Mount Button, experienced 

severe volcano-seismic crises in 1984 and 1988 that 

resulted from the near-surf ace movement of magma yet 

did not yield an eruption. Iliamna volcano experienced 

similar unrest in 1996. All the volcanoes except Mount 

Wrangell, a possibly active volcano, are in the Aleutian 

volcanic arc.

Most reports of eruptive activity date from 1760 on 

although a few vague reports of eruptions exist between 

1700 and 1760 (Grewingk, 1850). At least 265 historical 

eruptions have occurred at 29 Alaskan volcanoes and 

another 45 are possible since 1760 giving a frequency rate 

of 1.1-1.3 eruptions per year. Since many eruptions early 

in this period surely went unreported, this is a minimum 

figure.

The problem of estimating eruption frequency through 

an analysis of the historical record is well-illustrated in 

Fig. 5 A where the number of eruptions per decade in the 

Aleutian Arc is plotted for the past 200 years. Reported 

eruptions show a general increase beginning in the 1870- 

1880 decade and continuing to the 1920-1930 decade 

where the rate of increase levels off. This increase is 

assumed to represent expanded travel to this remote area 

and advances in rapid communication (i.e., newspapers 

and more recently radio) of eruptive events; interestingly 

enough, the decades including World Wars I and II show 

significant decreases. The sharp increase in the 1980-1990 

decade has been followed by a return (estimated in part 

see caption of Fig. 5) to pre-1980 levels.

A more meaningful eruption frequency estimate can 

perhaps be calculated over the 50 year period 1945 (the 

end of World War II) through 1994, a time that marked the

IV
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

40 45 50 55 60

Si02 WT.%

Figure 4A Silica distribution diagram for entire Aleutian arc.

40 45 50 55 60 65 70 75 80 

Si02 WT.%

Figure 4B. Silica distribution diagram for continental margin 

part of Aleutian arc.

55 60 65 

SiO, WT.%

Figure 4C. Silica distribution diagram for oceanic island-arc 

part of Aleutian arc.

beginning of widespread air travel and other commerce in 

this remote part of the world. During this 50 year interval, 

90 eruptions have been reported from 23 volcanoes for a 

frequency of about 2 (1.8) eruptions per year.

Although these are estimates of the number of 

separate eruptions per year, many individual eruptive 

episodes are spread over weeks and even months. In any 

one year, therefore, it is not unusual for 3 or 4 Alaskan 

volcanoes to have experienced eruptive activity.

The number of separate eruptions from individual 

historically active centers ranges from 1 to 39 and over 

60% of the 265 eruptions have come from only 7 volcanoes (Veniaminof, Pavlof, Shishaldin, Akutan, Makushin, 

Okmok, and Bogoslof Island). These frequently active 

volcanoes occur along (or, in the case of Bogoslof, behind) 

a 640 km of the arc in an area where movement between 

the North American and Pacific plates is most nearly 

orthogonal. Most of these volcanoes are also marked by 

long-lived but sporadic strombolian and vulcanian eruptive 

activity resulting in some difficulty in defining individual 

eruptions.

ALEUTIAN ARC

1800 1820 1840 1860 1880 1900 1920 1940 1960 1980 

TIME (1800 TO 2000)

Figure 5. A plot of the number of eruptions reported per decade 

for the period 1800-2000 for the Aleutian Arc; the 1990-2000 

number is estimated by doubling the number of eruptions from 

1990-1995.
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Historically Active Volcanoes
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

CATALOG OF ACTIVE VOLCANOES OF THE WORLD

(CAVW)

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

Form and structure

Mt. Wrangell is a large 

andesitic shield volcano 

with a volume of about 900 

km3 (Nye, 1983) (fig. 6). Its 

top is capped by a 4 by 6 

km, ice-filled summit 

caldera whose depth may 

exceed 1 km (Benson and 

Motyka, 1979). The caldera 

is apparently of nonexplosive origin (Richter and 

others, 1984) formed in 

response to the withdrawal 

of magma from high-level 

reservoirs beneath the 

summit area. Three small (< 1 

km in diameter) post-caldera 

craters, all geothermally 

active, occur along the west 

and north margin of the 

caldera. Mt. Zanetti (3965 m) 

a large (450 m high) steepsided, relatively undissected 

cinder-spatter cone occurs 

high on the northwest flank of 

the shield and may be the

source of some lava flows. Lavas on the southwest flank 

have flowed as much as 58 km from their source despite 

being phenocryst-rich andesite, a mobility attributed to a 

very high eruption rate (Nye, 1983).

MOUNT WRANGELL VOLCANO

WRANGELL VOLCANO

SHIELD WITH SUMMIT CALDERA

WEST END OF WRANGELL MOUNTAINS, 80 KM

EAST OF GLENNALLEN IN SOUTH-CENTRAL

ALASKA

62°00'N, 144°01'W

4317 M

GULKANA, NABESNA, VALDEZ, MCCARTHY

1105-02

144°00'

6 2° 00'

Contour Interval 500 feet

n ice

Rock

144°00' From U.S. Geological Survey 

Valdez, Nabesna, McCarthy, 

and Gulkana quadrangles 

(1: 250,000)

Figure 6. Topographic map of Mount Wrangell showing location 

of caldera and post-caldera fumarolic vents.

Volcanic activity

Mt. Wrangell is the only historically active volcano in 

the extensive Wrangell volcanic field of Miocene to 

Holocene age. Richter and others (1995) list three reports 

(1784, 1884-85, and 1900) of eruptive activity but at least 

the first two of these are suspect. Historical activity, which
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

has been limited to fumaroles and minor phreatic eruptions 

in the summit craters, apparently waxes and wanes in 

response to changes in the summit heat flux. In addition, 

some evidence suggests that increases in the heat flux and 

concomitant increases in fumarolic and phreatic activity 

have followed major earthquakes in south-central Alaska 

(Benson and Motyka, 1979). Photographs of the ashcovered summit of Mt. Wrangell that appear in the reports 

of Mendenhall and Schrader (1903) and Mendenhall 

(1905) may reflect an increase in activity following the 

September 3, 1899 Yakutat earthquake. Although major 

eruptions and lava flows have been reported on Wrangell 

in the past, none have ever been confirmed (Mendenhall, 

1905; Benson and Motyka, 1979; Richter and others, 

1995).

Composition

Wrangell lavas range from basalt to dacite (52 to 66 

percent SiO2) in composition (Nye, 1983) and exhibit 

medium-K calcalkaline affinities (figs. 6A, B,). Predominant lavas are porphyritic 2-pyroxene andesites (57 to 61 

percent SiO2).

O

O

(N

Rhyoiite

70 75 80

Si02 WT. C

Figure 6A. Total alkalies-silica diagram of Wrangell volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks (small 

dots) of continental affinity (those located east of 165°W 

longitude). Discriminant lines and field names (Le Bas and 

others, 1986) are explained on Figure 2.

O 4 

CD

O '--4'* vft >..'"''' 

*'.--'

45 50 55 60 65

SiO2 WT.%

70 75

Figure 6B. FeO/MgO-silica diagram of Wrangell volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of 165°W longitude). 

Tholeiitic versus calc-alkaline discriminant line from Miyashiro 

(1974).
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

NAME OF SATELLITIC VENT: 

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

MOUNT SPURR

SPURR VOLCANO

STRATOVOLCANO AND EXPLOSION CALDERA

CRATER PEAK

ON THE EAST FLANK OF THE ALEUTIAN

RANGE, 130 KM WEST OF ANCHORAGE.

61°18'N, 152°15*W

3374 M, CRATER PEAK 2309 M

TYONEK

1103-04

Form and structure

Mount Spurr is a Quaternary stratovolcano located 

near the northeastern end of the Aleutian volcanic arc 

(fig. 7). It is the easternmost historically active volcano in 

the Aleutian arc and is the highest of several snow- and 

ice-covered peaks that appear to define a large, dissected 

stratovolcano (Juhle and Coulter, 1955).

Capps 61 «20- 

(1929) suggested 

that a summit 

caldera, largely 

buried by ice, is 

associated with 

Mount Spurr. 

Later, Juhle and 

Coulter (1955) 

disagreed with 

the caldera 

interpretation 

suggesting that 

the peaks around 

Mount Spurr 

only coincidentally resemble 

the rim of a

large subsidence structure. Most recent studies, however, 

suggest that ancestral Mt. Spurr, constructed during late 

Pleistocene time (Turner and Nye, 1986), was partially 

destroyed by a major Bezymianny-type eruption possibly 

as late as early Holocene time (Riehle, 1985; Nye and 

Turner, 1990). The eruption produced a voluminous 

volcanic debris avalanche and subsequent pyroclastic 

flows that resulted in the formation of a 5- to 6-kmdiameter explosion caldera (fig. 7). The volcanic debris 

avalanche contains blocks as much as 100 m in diameter 

and traveled a minimum of 25 km. The overlying pyroclastic flows are partially welded and are composed chiefly of 

high silica andesite. Present Mt. Spurr is the highest of

several post-caldera, centrally located, ice-carved cones or 

domes.

The youngest volcanic feature at Mount Spurr is a 

satellitic cone, Crater Peak, located in the breach in the 

caldera about 3.2 km south of Mount Spurr (fig. 7). Crater

152"oa"

r

I |Gt«cl«r« and urflclalf 

I I d«po«lts'

Modified after Nye, 1967,1990

Figure 7. Generalized geologic map of the Mount Spurr volcanic 

center; modified from Nye (1987).

Peak has a summit crater that is itself slightly breached 

along the south rim; the north wall of the crater exposes 

the truncated remains of an older dome or lava lake. Crater 

Peak has been the source of all Late Holocene eruptive 

activity at Mt. Spurr (Riehle, 1985). Before the 1992 

eruption, a small crater lake occupied the bottom of the 

crater.
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Volcanic activity

July, 9 - July 10, 1953 and 

June 27 - September 17, 1992

Mt. Spurr has only two historical eruptions, although 

Riehle (1985) identified 35 Holocene tephra layers in the 

Cook Inlet area that he attributed to Mt. Spurr. Activity 

before 1953 consisted of occasional vapor emissions from 

the summit of Mt. Spurr; Crater Peak was ice-filled and 

had no fumaroles.

The first historical eruption of Mt. Spurr occurred on 

July 9, 1953, when the Crater Peak vent, in two main 

eruptive pulses on two succeeding days, produced a tephra 

blanket about 4 mm thick at Anchorage and detectable up 

to 350 km to the east (Wilcox, 1959). Ash in the initial 

eruptive pulse rose to 20 km. Lahars swept down valleys 

heading on the south flank of Crater Peak, resulting in a 

dam on the Chakachatna River (fig. 7) which raised the 

level of Chakachamna Lake at least 3 m (Juhle and 

Coulter, 1955). Activity was short-lived and essentially 

confined to the two days.

Activity between 1953 and 1992 consisted of small 

fumarolic emissions from the inner walls of Crater Peak 

crater. A warm (56°C) crater lake about 45 m in diameter 

formed sometime between the 1953 eruption and 1970. 

Infrequent aerial observations of the Mt. Spurr summit 

itself during this interval showed only minor vapor 

emissions and yellow discoloration of the snow around a 

small vent area near the summit.

The most recent eruption at the Mt. Spurr center 

began on June 27, 1992 with the first of three explosive 

events that occurred over a three month period (Alaska 

Volcano Observatory, 1993; Eichelberger and others, 

1995). A slow but steady increase in seismicity beneath 

and around the center began 10 months before the eruption. By early June, bursts of shallow tremor were occurring at Crater Peak and the small crater lake was showing 

dramatic changes including increased SO^Cl ratios, a 

change in color from turquoise to gray, and vigorous 

upwelling. Tremor burst duration increased significantly 

on June 24 and continuous tremor began midday on June 

26 (Alaska Volcano Observatory, 1993). An abrupt 

increase in tremor amplitude at 0705 on June 27 indicated 

onset of the first eruptive pulse. The volcano was hidden 

by clouds which prevented direct observation. During the 

4 hour event, small pyroclastic flows mixed with snow 

swept down the south flank of the cone, and an ash plume 

rose to an estimated height of 14.5 km, based on C-band 

radar (Rose and others, 1995); pilot reports suggest a 

plume height of 15-18 km. Southerly winds carried tephra 

to the north over the sparsely populated Alaska Range. 

About 2 mm of ash fell in Denali National Park 260 km 

downwind and ashfall was observed as far north as Manly

Hot Springs, 420 km downwind. Tephra volume was about 

44 x 106 m3 and consisted mostly of juvenile andesite 

(Alaska Volcano Observatory, 1993). Seismicity decreased 

to pre-August 1991 levels by July 8 and remained low 

during July to mid-August.

The second eruptive phase of 1992 began on the 

afternoon of August 18 preceded by only a short tremor 

burst. C-band radar data indicates the ash plume rose to 

about 14 km (Rose and others, 1995) (pilots estimated the 

plume height at about 18 km) and small pyroclastic flows 

again descended the east and southeast flanks of Crater 

Peak. The eruption lasted 3.5 hours and produced about 52 

x 106 m3 of ash. Westerly winds carried the tephra eastward over Anchorage, across the Chugach Mountains and 

northern half of Prince William Sound, and southeastward 

toward Yakutat. Up to 3 mm of sand-sized ash fell in 

Anchorage and coastal communities 1200 km downwind 

reported dustings of fine ash (Neal and others, 1995). 

Anchorage International Airport was closed for 20 hours 

because of the ashfall.

Following the August 18 event, seismicity remained 

elevated but no precursory activity occurred until the late 

hours of September 16 when a 3-hour-long increase in 

tremor culminated in an 11-minute-long eruptive event. An 

hour and a half later, a much larger eruptive phase began 

that lasted 3.5 hours (Alaska Volcano Observatory, 1993). 

Pyroclastic flows swept down the south, east, and eastnortheast flanks of Crater Peak (Miller and others, 1995). 

The flows entrained snow and other surface debris, 

developing into lahars, of which at least one temporarily 

dammed the Chakachatna River (Meyer and Trabant, 

1995). A narrow field of ballistics, ejected near the end of 

the eruption, extends at least 10 km east from the vent 

(Waitt and others, 1995). Southwesterly winds carried the 

ash cloud across upper Cook Inlet, narrowly missing 

Anchorage, up the Matanuska Valley and across eastern 

Alaska. At least 1 mm of ash fell in Glenallen, 350 km 

east, and a very light dusting was reported at Burwash 

Landing, Yukon Territory, 700 km east. Photographs taken 

from the Space Shuttle several days later show the thin but 

undispersed ash cloud over western Quebec, Canada. Bulk 

tephra volume was about 56 x 106 m3 .

After the September 16-17 eruption, seismicity 

remained high through December with intense earthquake 

swarms occurring October 2-6, November 9-10, and 

December 21-27. The seismic energy release of the 

November 9-10 swarm was the greatest of the entire 1992 

eruptive period and this activity is regarded as a "failed 

eruption" (Power and others, 1995). Seismicity gradually 

declined through the first half of 1993 to near-background 

levels.
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Composition

Lava flows comprising the main portion of the precaldera stratovolcano are porphyritic andesite (58%-60% 

SiO2 ; Nye and Turner, 1990; figs. 8 and 9) containing 30% 

to 50% phenocrysts of chiefly plagioclase, and subordinate 

clino- and orthopyroxene. Textures are either pilotaxitic or 

hyalopilitic; some samples display a strongly developed 

glomero-porphyritic texture. Inclusions of fine-grained, 

equigranular gabbro (?) or diorite (?), although not 

exceeding about 5% of any sample, occur in nearly all 

samples. Some samples contain rare subhedral, heavily 

oxidized hornblende. Pumice from the early Holocene (?) 

pyroclastic flows is high-silica andesite or low-silica dacite 

(60%-63% SiO2 ; Nye and Turner, 1990).

Juvenile material from all three eruptions in 1992 are 

essentially the same composition (figs. 8, 9) calcalkaline 

andesite with 56.7% SiO2 (Nye and others, 1995) and 

comprise porphyritic hornblende-bearing andesite with 

brown, microlite-rich andesitic groundmass glass (Alaska 

Volcano Observatory, 1993). A variety of metamorphic 

xenoliths were incorporated in deposits including gneiss 

clasts, partly remelted and highly inflated garnet-plagioclase-wollastonite skarn, and plagioclase-quartz-glass rock 

(Alaska Volcano Observatory, 1993).

45

SiO, WT.%

Figure 8. Total alkalies-silica diagram ofSpurr volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of 165°W longitude). 

Discriminant lines and field names (Le Bas and others, 1986) are 

explained on Figure 2.

8

7

6

O 5

O)

? 4

O

Q) li- 3 

2 

1

45 50 55 60

SiO,, WT.%

65 70 75

Figure 9. FeO/MgO-silica diagram ofSpurr volcanic rocks (solid 

circles) and other Aleutian arc volcanic rocks (small dots) of 

continental affinity (those located east of 165''W longitude). 

Tholeiitic versus calc-alkaline discriminant line from Miyashiro 

(1974).
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

Form and structure

Redoubt Volcano is a steep-sided cone about 10 km in 

diameter at its base and with a volume of 30-35 km3 . The 

volcano is composed of intercalated pyroclastic deposits 

and lava flows and rests on Mesozoic granitic rocks of the 

Alaska-Aleutian Range batholith (Till and others, 1993; 

1994). It has been moderately dissected by the action of 

numerous alpine glaciers. A 1.8-km-wide, ice-filled 

summit crater is breached on the north side by a northward-flowing glacier, informally known as the Drift 

Glacier, which spreads into a piedmont lobe in the upper 

Drift River Valley. The most recently active vent is located 

on the north side of the crater at the head of the Drift 

glacier. Holocene lahar deposits in the Crescent River and 

Drift River valleys (fig. 10) extend downstream as far as 

Cook Inlet.

Volcanic activity

Vapor emissions 1933, 1965, 1967?

Ash-rich explosions 1902, 1966, 1967-68?, 1989-90

Volcanism at Redoubt may have begun as much as 

0.88 Ma ago, although the bulk of the cone has been built 

within the last 200,000 years (Till and others, 1993). 

Extensive 3500-year-old lahar deposits fill the Crescent 

River valley and dam Crescent Lake (Riehle and others, 

1981). The oldest historical eruption occurred in 1902, 

when explosions were heard 175 km away and widespread 

ashfall was reported in the Cook Inlet basin (Martin and 

Katz, 1912; The Alaskan, Sitka, March 29, 1902). Vapor 

emissions were reported in May 1933 and JanuaryFebruary 1965. During late January and early February 

1966, an explosive eruption produced ash plumes as high 

as 6100 m; an associated burst of meltwater caused 

destruction of the glacier draining north from the summit 

crater and subsequent flooding downstream as far as Cook 

Inlet (Sturm and others, 1986). A "series of clouds" during 

January 1967 and five explosions during December 1967

REDOUBT VOLCANO

NONE

STRATOVOLCANO

170 KM SOUTHWEST OF ANCHORAGE, ALASKA

IN THE ALASKA-ALEUTIAN RANGE

60°28'N, 152°45'W

3108 M

KENAI

1103-03

152"50'

Contour interval 1000 feet

I I lce

f.yy"i 1989-90 pyroclastic and

rjVlttj flood deposits

{ ,. 1 1 Crescent River lahar

Redoubt Volcanics 

||||i| plutonic and volcaniclastic rocks

Till and others. 1993

18Is

Figure JO. Generalized geologic map of Redoubt volcano; 

modified from Till and others, 1993.

through April 1968 were reported by Wilson and Forbes 

(1969).
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

The most recent eruption at Redoubt began with a 

major phreatomagmatic, vent-clearing explosion at 

9:47 am on December 14, 1989 (Brantley, 1990; EOS, 

1990; Miller and Chouet, 1994) after less than 24 hours of 

intense precursory seismicity. Three more ash-rich 

explosions occurred the following day, December 15, with 

the last blast generating a pyroclastic flow down the Drift 

Glacier. The resulting debris flow contained entrained ice 

blocks as large as 10 m across and crested about 8 m above 

the river channel near the Drift River Oil Terminal, 35 km 

downstream (Waitt and others, 1994). A Boeing 747 

enroute from Amsterdam that flew into the ash cloud 

several hours after the eruption experienced complete 

engine failure and narrowly avoided tragedy when the 

crew successfully restarted the engines and safely landed 

in Anchorage (Casadevall, 1994).

These initial explosive events were just the first of 23 

major explosive events between December 1989 and April 

1990. Following the mid-December explosive phases, the 

crater vent emitted only minor ash and steam for the next 

5-7 days. From December 22 to January 2, 1990, however, 

a large, over-steepened lava dome grew over the vent. At 

5:48 pm on January 2, the first of two powerful explosions 

destroyed most of the dome and sent ash plumes to over 12 

km. Massive block and ash avalanches down the Drift 

Glacier generated the largest debris flow of the eruption, 

completely covering the 2-km-wide valley floor and 

spilling into Cook Inlet. Flood waters entered the oil 

terminal, as much as 75 cm deep in some buildings, and 

caused a temporary halt in operations.

Three eruptions occurred in the next two weeks during 

which time the vent remained open. The January 8 event 

occurred with no precursory warnings and the resulting 

ashfall on the Kenai Peninsula disrupted commerce and 

transportation. Open-vent eruptions on January 11 and 16 

resulted in minor debris flows down the Drift River.

After the January 16 eruption, another period of dome 

growth ensued through mid-February. This dome was 

smaller than the earlier dome but larger than succeeding 

domes (Miller, 1994). Early on February 15, the dome was 

destroyed in an explosive eruption that again sent a large 

debris flow down the Drift River and blanketed the lower 

Kenai Peninsula with ash. A pyroclastic flow and surge 

traveled down the canyon, across the piedmont lobe of 

Drift Glacier, and swept up the opposite valley wall 700 m 

topping the ridge (Gardner and others, 1994). Flow down 

the Drift River was largely diverted into a side drainage 

that carried flood waters close to oil storage tanks at the 

downstream oil terminal prompting reinforcement of the 

containment dikes surrounding the tank farm. A new dome 

began growing immediately following the eruption.

On February 21, the new, but considerably smaller, 

dome was destroyed, marking the beginning of a new 

trend in eruptive behavior. Characteristically, small domes 

were emplaced and subsequently destroyed explosively or 

by gravitational collapse, resulting in debris avalanches 

down the now ice-free canyon leading down to the Drift 

River valley, and flooding down the Drift River. Ten such 

eruptions followed from February 24 to April 21 at 4 to 8 

day intervals.

Following the April 21 eruption, growth of the present 

lava dome began and continued through early June. During 

the next several months, seismic activity declined dramatically and only steam emissions and minor rock falls from 

the dome were recorded as the eruption came to an end.

The 1989-90 eruption of Redoubt seriously effected 

the populace, commerce, and oil production and transportation throughout the Cook Inlet region and air traffic as 

far away as Texas. Total estimated economic costs are 

$160 million (Tuck and others, 1992), making the eruption 

of Redoubt the second most costly in U.S. history.
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Composition

The oldest deposits of Redoubt Volcano include 

pyroclastic and hypabyssal rocks of calc-alkaline andesitic 

to dacitic composition (62-68% SiO2 ; figs. 11, 12). Flows 

and pyroclastic deposits that compose the majority of the 

present cone range from basalt to andesite (49-62% SiO2). 

Most are porphyritic containing phenocrysts of plagioclase, the dominant phase, and variable amounts of olivine, 

clinopyroxene, orthopyroxene, and hornblende. Juvenile 

materials from the most recent eruption cycle are all 

plagioclase-phyric hornblende andesites with SiO2 ranging 

from 59.3% to 61.9% (Nye and others, 1994) and are 

similar to lavas from the 1966 eruption of Redoubt.

50 55 60 65 70 

SiO2 WT.%

75 80

Figure 11. Total alkalies-silica diagram of Redoubt volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks (small 

dots) of continental affinity (those located east of!65"W 

longitude). Discriminant lines and field names (Le Bas and 

others, 1986) are explained on Figure 2. Samples with <52% 

SiO^ are cumulate blocks.

8

7

6

O 5

O)

P 4

O

0) 

Li. 3

2

1

45 50 55 60 65 

SiCX WT.%

70 75

Figure 12. FeO/MgO-silica diagram of Redoubt volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of 165"W longitude). 

Tholeiitic versus calc-alkaline discriminant line from Miyashiro 

(1974).

10
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

ILIAMNA VOLCANO

NONE

STRATOVOLCANO

225 KM SOUTHWEST OF ANCHORAGE, IN THE

ALEUTIAN RANGE AT THE NORTH END OF THE

ALASKA PENINSULA

60°02'N, 153°04'W

3,053 M

LAKE CLARK

1103-02

Form and structure

Iliamna volcano is a broad, deeply dissected 

and highly altered, roughly cone-shaped mountain 

at the north end of a 5-km-long ridge trending 

N10°W (fig. 13). Most of the volcano is covered by 

perennial snow and ice and numerous glaciers 

radiate from the summit area. Large avalanche 

deposits occur on the flanks of the volcano, 

particularly down the Umbrella Glacier on the 

southwest side of the volcano.

The volcano is a typical composite stratovolcano composed of interbedded andesite lava flows 

and pyroclastic rocks. Steep, inaccessible 600-mhigh headwalls along the southern and eastern 

flanks extend nearly to the summit exposing a 

cross section of the volcanic stratigraphy.

Iliamna is built on a basement of Jurassic 

granitic rocks of the Aleutian Range batholith 

(Detterman and Hartsock, 1966) that are juxtaposed against older, Lower Jurassic lava flows and 

pyroclastic rocks by the Bruin Bay fault, which lies 

several kilometers east of the summit (fig. 13).

Volcanic activity

The only well documented historical volcanic 

activity at Iliamna is that of numerous, small, 

solfataric vents at about 2740 m elevation on the 

eastern flank (fig. 13). Condensate plumes have 

been observed extending to an estimated 1000 m 

above the mountain. Although several reports of 

"smoke" or "steam" rising from the volcano are 

received each year, aerial inspections invariably 

reveal that the activity consists of unusually large clouds 

of condensate related to the summit fumaroles. These 

reports are particularly common in the spring and fall,

From Detterman and Hartsock (1966) 

3 Miles

3 Kilometers

Alluvial and glacial deposits, undivided

Iliamna lava flows and associated pyroclastic rocks

Quartz dlorlte

Volcanic breccia, lava flows, metallmestone, argilllte, 

metatuff, sandstone, slltstone, shale, undivided

Figure 13. Generalized geologic map of Iliamna volcano; 

modified from Detterman and Hartsock (1966).

11
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

probably because of favorable meteorological conditions 

(Johnston, 1979), and similar events have undoubtedly 

been reported as "smoke" in the past. Therefore, although 

Coats (1950) lists several reports of "smoke", and an 

eruption in 1867, documentation is poor and validity of the 

reports is questionable. Except for the summit fumarolic 

activity, it is uncertain and perhaps unlikely that Iliamna 

Volcano has been historically active.

Although no historic (i.e., within the last 200 years) 

eruptions can be confirmed, recent studies (Beget, 1996) 

have identified coastal lahars containing juvenile clasts 

that originated from Iliamna Volcano -300 14CyBP and are 

overlain by 250-year-old trees. These deposits record the 

most recent eruptive activity from the volcano. However, 

two strong seismic swarms recorded beneath the volcano 

in 1996 (Neal and McGimsey, 1997) indicate the volcano 

remains restless and subject to further eruptions.

Composition

The volcano is composed of interbedded hyperstheneaugite andesite flows and pyroclastic deposits (figs. 14, 

15). Most of the flows are light gray and range in thickness from 25 to 120 m. The lava flows contain phenocrysts 

of plagioclase and subordinate hypersthene and augite in a 

dense pilotaxitic groundmass composed of randomly 

oriented microlites with relatively little glass. Sparse 

olivine occurs in some of the flows but is generally less 

than one percent of the mode.

50 55 60 65 70 75

SiCL WT.%

Figure 14. Total alkalies-silica diagram of Iliamna volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks (small 

dots) of continental affinity (those located east of 165°W 

longitude). Discriminant lines and field names (Le Bos and 

others, 1986) are explained on Figure 2.

8

7

6

O 5

D)

P 4

O

0) U. 3 

2 

1

.. .i ', ;

45 50 55 60 65 70 75

SiCL WT.%

Figure 15. FeO/MgO-silica diagram of Iliamna volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of 165°W longitude). 

Tholeiitic versus calc-alkaline discriminant line from Miyashiro 

(1974).

12
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME: 

SYNONYMS:

TYPE: 

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

Form and structure

Augustine Island, an 8 by 11 km island in lower Cook 

Inlet (fig. 16), is composed almost entirely of the deposits 

of Augustine Volcano. Jurassic and Cretaceous 

sedimentary strata form a bench on the south side 

of the island and are overlain by granitoid glacial 

erratics and volcanic hyaloclastites. The volcano 

consists of a central dome and lava flow complex, 

surrounded by pyroclastic debris. The irregular 

coastline of Augustine Island is due to the 

repeated catastrophic collapse of the summit 

dome, forming debris avalanches down the flanks 

and into Cook Inlet. At least 11 avalanches have 

occurred in the past 2000 years with an average 

recurrence interval of about 150-200 years (Beget 

and Kienle, 1992; Beget, 1986).

Augustine lies within the area of uplift 

resulting from the 1964 Alaska earthquake; 30- 

33 cm of uplift was measured on the northwest 

side of the island (Detterman, 1968). A 25-meter- ' 

high, south-facing submarine scarp 3 km south of 

the island, of similar orientation to joint sets in 

sedimentary rocks of the Kamishak River area 

(on the Alaska Peninsula), is almost certainly of 

tectonic origin.

Volcanic Activity

1812, 1883, 1908?, 1935, 1963-64, 1976,

1986

Augustine Volcano is the most frequently 

active and the youngest of the Cook Inlet 

volcanoes. Detterman (1973) considered Augustine to be entirely Quaternary and Johnston (1979) 

concluded that volcanism at Augustine began 

during the late Pleistocene Moosehorn glacial 

advance 19,000-15,500 yBP. Since its discovery

AUGUSTINE VOLCANO

ST. AUGUSTINE VOLCANO,

MOUNT ST. AUGUSTINE

CENTRAL DOME CLUSTER

290 KM SOUTHWEST OF ANCHORAGE, ON

AUGUSTINE ISLAND IN LOWER COOK INLET

59°23'N, 153°26'W

APPROXIMATELY 1,260 M

ILIAMNA

1103-01

by Captain James Cook in 1778, Augustine Volcano has 

had seven historical eruptions: 1812 (Doroshin, 1870), 

1883 (Davidson, 1884; Kienle and others, 1987; Siebert 

and others 1989), 1908 (Seward Weekly Gateway, March

Augustine 

Island

Interval 600 feel

1986 deposits 

dome and lava flow

pyroclastic flows 

lahars

1964 deposits 

1964 dome

Modified from Swanson and Kienle, 1988

1935 deposits

If 111"! 1936 dome and lava fl°

pre-1883 deposits

tl I Cretaceous and Jurassic 

 I sedimentary rocks

J

summit crater

Figure 16. Generalized geologic map of Augustine volcano; modified 

from Swanson and Kienle (1988).

13
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

14, 1908), 1935 (Anchorage Daily Times, April 3, July 13, 

1935; Detterman, 1973), 1963-64 (Detterman, 1968), 1976 

(Kienle and Shaw, 1979; Kienle and Swanson, 1985; 

Kamata and others, 1991), and 1986 (Kienle and others, 

1986; Yount and others, 1987). The activity in 1908, 

reported by the captain of a steamer enroute to Seward, 

was minor and probably did not produce any deposits.

The 1883 eruption appears to have been the most 

violent historical eruption of Augustine, and is thought to 

have generated a tsunami with wave heights of 7.5 to 9 m 

at English Bay on the Kenai Peninsula 80 km east of the 

island (Davidson, 1884). The tsunami has been attributed 

to a debris avalanche from the north side of the volcano 

into Cook Inlet (Kienle and others, 1987; Siebert and 

others, 1989).

The most recent eruption, which began on March 27, 

1986, after more than five weeks of increased seismic 

activity and continued through August 1986 (Smithsonian 

Institution, 1987), is probably typical of most Augustine 

eruptions. A nearly continuous ash-rich plume rose 3,000 

to 4,600 m; periodic explosive bursts reached altitudes of 

12,200 m (Yount and others, 1987). Numerous pyroclastic 

flows were generated in the early stages of the eruption 

and moved down the north flank. Several large flows 

reached the north shore 5 km away and entered the sea. 

Much of the snowpack on the upper flanks melted producing lahars (fig. 16). As the eruption evolved, generation of 

pyroclastic flows diminished and dome building began. A 

short lava flow also issued down a steep gully on the north 

flank.

Military and commercial air traffic was disrupted in 

upper Cook Inlet during the first week of the eruption 

when airborne ash was moving northward. Light ashfall 

occurred over most of the Cook Inlet area, and ash was 

detected as far north as the Brooks Range several days into 

the eruption (Yount and others, 1987).

Eruptions of Augustine typically consist of multiple 

phases spanning several months. During each phase, 

explosive ash eruptions are often accompanied by mudflows and pyroclastic flows. Usually the first phase is the 

most violently explosive; successive phases often include 

extrusion of lava, enlarging the central dome and lava flow 

complex.

50 55 60 65 70 75

Si02 WT.%

80

Figure 17. Total alkalies-silica diagram of Augustine volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks (small 

dots) of continental affinity (those located east ofl65"W 

longitude). Discriminant lines and field names (Le Bos and 

others, 1986) are explained on Figure 2. The rhyolites are 

individual pumice lapilli.

O 5

en

P 4

O

o li. 3

45 50 55 60 65 70 75

SiO2 WT.%

Figure 18. FeO/MgO-silica diagram of Augustine volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of 165°W longitude). 

Tholeiitic versus calc-alkaline discriminant line from Miyashiro 

(1974).

Composition

Augustine volcanic rocks are of calc-alkaline andesite 

and dacite composition (figs. 17, 18) but of the low-K, 

rather than medium-K variety. Phenocryst phases include 

plagioclase (the dominant phase), orthopyroxene, 

clinopyroxene, hornblende, and rare olivine. Much of the 

lava is rich in glass and highly vesicular.

14
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

MT. KATMAI, KATMAI CALDERA

KATMAI VOLCANO

STRATOVOLCANO WITH CENTRAL CALDERA

KATMAI NATIONAL PARK, 440 KM SOUTHWEST

OF ANCHORAGE, ON THE ALASKA PENINSULA

58° 16'N, 154° 59'W

2047 M

MT. KATMAI

1102-17

Form and structure

Katmai volcano is a large stratovolcano about 10 km 

in diameter with a central lake-filled caldera whose rim is 

about 4.2 by 2.5 km in area (fig. 19). The caldera rim has a 

maximum elevation of 2047 m and in 1975 the lake 

surface was at an elevation of about 1236 m. 

The estimated elevation of the caldera floor is 

about 995 m.

The volcano is one of five stratavolcanoes 

near the Novarupta dome, source of the 

voluminous pyroclastic flows erupted in 1912 

(Hildreth, 1983). It consists chiefly of lava 

flows, pyroclastic rocks, and non-welded to 

agglutinated air fall (Fenner, 1920; Hildreth, 

1983). The Quaternary volcanic rocks at Katmai 

and adjacent cones are less than 1500 m thick 

(Hildreth, 1983). Much of the volcano is 

mantled by snow and ice and several valley 

glaciers radiate out from the flanks and three 

glaciers originating from the upper caldera 

walls descend into the crater to the lake 

(Motyka and Benson, 1975).

about 2286 m and local villagers reported in 1898 that one 

of the volcanoes in the general area "smoked" occasionally.

Katmai volcano is built on the sedimentary 

rocks of the Naknek Formation of Late Jurassic 

age, which are exposed just west of the caldera 

rim at an elevation of about 1520 m, as well as 

north and southeast of the crater (Curtis, 1968; 

Riehle and others, 1987).

Volcanic activity

June 6-8, 1912

Little is known about the historical activity 

ofKatmai volcano before the great 1912 

eruption. Early Coast and Geodetic Survey 

maps suggest a pre-caldera summit elevation of

Contour Interval 1000 feet Riehle and others (1987)

Surficial deposits, undivided (Holocene and Pleistocene) 

[<= *] Pyroclastic flow deposits (Holocene) 

| | Dacific and rhyolitic domes (Holocene) 

IJI-jfiflll Younger central-vent deposits and rocks (Quaternary)

m^ Central vent deposits and rocks, undivided, Andesitic and dacitic lava flows, breccias, and

domes, (Pleistocene - Upper Tertiary)

Sedimentary rocks; hypabyssal intrusives; lava flows and pyroclastic rocks, undivided (Tertiary 

- Jurassic)

Quaternary volcanic vent

i i Subsidence structure

Synclinal axis

Figure 19. Generalized geologic map ofKatmai, Mageik, Martin Mountain, 

Trident, Knife Peak (Griggs) and Novarupta volcanoes after Riehle and 

Detterman (1993).

15
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

In June of 1912, the most spectacular Alaskan 

eruption in recorded history and the largest eruption in the 

world in the twentieth century resulted in the formation of 

a small summit caldera at Katmai volcano. The 60-hourlong eruption actually took place at a vent about 10 km to 

the west of Mt. Katmai (now marked by Novarupta dome) 

from which an estimated 30-35 km3 of ash flows and 

tephra were ejected (Hildreth, 1983; Fierstein and 

Hildreth, 1992) rather than at Mt. Katmai itself. Based on 

geochemical and structural relationships, Hildreth (1987) 

suggests that magma drained from beneath Katmai 

Volcano to Novarupta via the plumbing system beneath 

Trident Volcano (fig. 19). The withdrawal of magma 

beneath Katmai resulted in the collapse of the summit 

area, forming the caldera (Curtis, 1968; Hildreth, 1991). 

Following the subsidence, a small dacitic lava cone was 

emplaced on the floor of the caldera; this is the only 

juvenile material erupted from Katmai caldera during the 

historical eruption. In 1919, a lake covered a large part of 

the caldera floor, but by 1923 the lake was gone and 

numerous fumaroles, mud pots, and a large mud geyser 

were active (Fenner, 1930). Approximately 12-15 km3 of 

magma was vented during the 1912 eruption producing 

about 35 km3 of tephra. An estimated 11-15 km3 of ash 

flow tuff traveled 20 km northwest covering an area of 

about 120 km2 in what subsequently came to be known as 

the Valley of Ten Thousand Smokes. Maximum thickness 

of the ashflow is estimated to be about 250 m (Hildreth, 

1983). Light ash fall was reported as far away as the Puget 

Sound region (2400 km). Extremely fine ash blown into 

the stratosphere remained in suspension as aerosols for 

months and caused spectacular red sunsets in many parts 

of the world.

Composition

Katmai volcano is composed of rocks ranging in 

composition from low-silica and low-potassium andesite 

to dacite but two-pyroxene andesite (figs. 20, 21) is the 

most common rock type (Fenner, 1926). The andesite is 

commonly porphyritic with plagioclase and pyroxene 

phenocrysts in an aphanitic groundmass of plagioclase, 

hypersthene, augite, magnetite, and glass. Biotite and 

quartz are absent, and hornblende is rare.

SiO. WT.%

Figure 20. Total alkalies-silica diagram of Katmai volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of 165°W longitude). 

Discriminant lines and field names (Le Bas and others, 1986) are 

explained on Figure 2.

45 50 55 60 65 

Si02 WT.%

Figure 21. FeO/MgO-silica diagram of Katmai volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of 165°W longitude). 

Tholeiitic versus cole-alkaline discriminant line from Miyashiro 

(1974).

16
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

NOVARUPTA

NONE

PLINIAN PYROCLASTIC VENT WITH PLUG DOME

VALLEY OF TEN THOUSAND SMOKES, KATMAI

NATIONAL PARK, ALASKA PENINSULA

58°16'N, 155°09'W

841 M

MT. KATMAI

1102-18

Form and structure

The Novarupta dome is about 400 m in diameter and 

65 m high at its center (Curtis, 1968) (fig. 19), and is 

surrounded by a 2-km-wide, funnel-shaped structure 

(Hildreth, 1983; Goodliffe and others, 1991). The surface 

of the dome is completely fractured into chaotic blocks 

and crumble breccia. The dome is a plug-like feature 

emplaced within a low ejecta ring. Prominent scarps along 

the flanks of Baked, Falling, and Broken Mountains 

surrounding the Novarupta depression indicate considerable subsidence occurred following the 1912 eruption. 

Nearby stratovolcanoes (including Trident and Katmai) 

form a volcanic front trending N65°E; Novarupta lies 

about 4 km behind the front. Linear fractures normal to the 

front extend between Novarupta and Trident (Hildreth, 

1987).

southeast but light ash fall was reported as far away as the 

Puget Sound region (2400 km). Extremely fine ash blown 

into the stratosphere remained in suspension as aerosol for 

months and caused spectacular red sunsets in many parts 

of the world.

Voluminous rhyolitic eruptions are typically followed 

by collapse of the vent and formation of a caldera. 

However, local complex magma reservoirs and plumbing 

systems resulted in the summit collapse at Katmai, 10 km 

to the east, in response to magma transfer towards Novarupta, possibly via Trident (Hildreth, 1983, 1987, 1991).

Following the pyroclastic eruption, the dome was 

emplaced near the center of the vent region. Fumarolic 

activity in the vent area has subsequently decreased and no 

other eruptions have been reported.

Volcanic activity

June 6-9, 1912

The eruption of 1912, largest twentieth century 

eruption in the world, produced the largest historic ash 

flow sheet (see frontspiece) deposited entirely on land 

(Hildreth, 1983). Eruptive activity started early in the 

afternoon of June 6, 1912 with the violent eruption of 

rhyolitic pumice and ash beginning about 1:00 p.m. 

Emplacement of the rhyolitic ash flow began concurrent 

with the plinian eruption and was followed continuously 

by fallout and ash flows zoned from rhyolite to andesite 

that lasted for about 20 hours (Fierstein and Hildreth, 

1992). Approximately 12 km3 of magma was vented 

during the 1912 eruption producing about 30 km3 of 

tephra. An estimated 11 km3 of ash flow tuff traveled as far 

as 20 km northwest covering an area of about 120 km2 in 

what subsequently came to be known as the Valley of Ten 

Thousand Smokes. Maximum thickness of the ashflow is 

estimated to be about 250 m (Curtis, 1968). About 17 km3 

of airfall tephra was carried preferentially east and

Composition

Three distinct magmas (rhyolite, dacite, and andesite) 

were mechanically and complexly intermingled during the 

1912 eruption producing mixed deposits with a range of 

bulk composition. The main ash flow is compositionally 

zoned with the earliest part nearly all rhyolite and the later 

half progressively more dacitic and andesitic (Hildreth, 

1983). The plug dome is rhyolite, contaminated with a 

minor amount of interbanded dacite and andesite lava. The 

bulk SiO2 content is 77% for the rhyolite, 66-64.5% for the 

dacite, and 61.5-58.5% for the andesite (figs. 22,23). 

Rhyolite ejecta is phenocryst-poor, in contrast to the 

andesite and dacite ejecta, which contain many 30-45% 

phenocrysts. Phenocryst minerals are quartz (rhyolite 

only), augite (all except rhyolite), plagioclase, 

orthopyroxene, titanomagnetite, ilmenite, apatite, pyrrhotite, and rare olivine (andesite only) (Hildreth, 1983).

17
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

45 55 60 65 70 

SiCL WT.%

75 80

Figure 22. Total alkalies-silica diagram ofNovarupta volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks (small 

dots) of continental affinity (those located east of!65°W 

longitude). Discriminant lines and field names (Le Bas and 

others, 1986) are explained on Figure 2.

7

6

O 5

D)

P 4

O

0)

u. 3 

2 

1

45 50 55 60 65 70 75

WT.%

Figure 23. FeO/MgO-silica diagram ofNovarupta volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of 165°W longitude). 

Tholeiitic versus calc-alkaline discriminant line from Miyashiro 

(1974).

18
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

Form and structure

Trident is an eroded volcanic complex consisting of 

three stratovolcanoes and numerous domes, as high as 

1864 m in elevation, along a northeast-southwest oriented 

volcanic front (fig. 19) on the Alaska Peninsula (Hildreth, 

1987). A new fragmental cone was built beginning in 1953 

at an altitude of 1097 m in an amphitheater on the 

southwest flank of the southwest peak.

Volcanic activity 

1953-1974

There is no evidence of recent eruptive activity at the 

several older summits of Trident, nor have there been any 

reports of historical activity, except fumarolic activity on 

the east side. However, a satellite cone formed February 

15, 1953 on the southwest flank of Trident following an 

explosive eruption that sent ash to an altitude of over 

9 km (Snyder, 1954; Ray, 1967). A succession of blocky 

lava flows were erupted in 1953, 1957, 1958, and 1959- 

1960 from the new vent. Ash eruptions, some to altitudes 

over 12 km, also occurred (Ray, 1967). By 1960 the 

fragmental cone had grown nearly 260 m high, and the 

sequence of viscous flows, up to 300 m thick and covering 

an area of 5 km2 south of the volcano, had been extruded 

(Snyder, 1954; Decker, 1963). Phreatic explosions and 

plug emplacements within the small crater of the cone 

continued until 1974. In the 1980's and 1990's, steam and/ 

or vapor continued to rise from the central vent area of the 

new cone as well as from numerous sulfurous fumaroles 

on the near-vent portion of the blocky lava flows.

Composition

Trident lavas are andesitic to dacitic (figs. 24, 25) in 

composition (Ray, 1967; Kosco, 1981). The dominant 

phenocrysts are zoned plagioclase, hypersthene, 

clinopyroxene, titanomagnetite, and rimmed olivine. The

TRIDENT COMPLEX

TRIDENT VOLCANO

CLUSTER OF THREE STRATOVOLCANOES

AND SEVERAL DOMES

KATMAI NATIONAL PARK, ALASKA PENINSULA

58°14'N, 155°07'W

1097 M (ELEVATION OF 1953 DOME)

MT. KATMAI

1102-16

five flows erupted from the new vent during 1953-1960 

are olivine-bearing, two pyroxene, high-silica andesite 

(Ray, 1967).

Si02 WT.%

Figure 24. Total alkalies-silica diagram of Trident volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of165°W longitude). 

Discriminant lines and field names (Le Bas and others, 1986) are 

explained on Figure 2.

O 5 

en

P 4

O

0) U. 3

45 50 55 60 65 70 75

Si02 WT.%

Figure 25. FeO/MgO-silica diagram of Trident volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of 165"W longitude). 

Tholeiitic versus calc-alkaline discriminant line from Miyashiro 

(1974).

19
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE:

CAVW NUMBER:

MOUNT MAGEIK

NONE

COMPOSITE VOLCANO

KATMAI NATIONAL PARK, 450 KM SW OF

ANCHORAGE

58°11'N,1550 14'W

ABOUT 2165 M

MT. KATMAI 

1102-15

Form and structure

Mount Mageik is a broad cone-shaped volcano that 

rests on a basement of Jurassic sedimentary rocks at the 

northeast end of a 12-km-long basement ridge shared by 

neighboring Mount Martin (fig. 19). The summit area, 

which is largely ice-covered, consists of a central high 

peak (elevation 2165 m) and three smaller topographic 

highs, each a separate vent-cone. A small (< 1 km in 

diameter) phreatic crater on the northeast side of the 

central peak contains a crater lake and supports vigorous 

fumarolic activity accompanied by sulfur deposition. The 

slopes of the volcano are moderately dissected by glacial 

ice, except the young lava flows of the east side. Two 

small debris avalanches, including the Mageik landslide 

one of which occurred during the 1912 Katmai eruption 

(Griggs, 1922) originated from areas high and low on the 

south flank. The 1912 avalanche, containing boulders as 

big as 3 to 5 m, travelled 6 km down the broad valley of 

Martin Creek, south and east of Mount Mageik.

Novarupta in 1912 and at Trident in 1953-1968..." 

Fumaroles from the summit crater are the only documented, historical emissions of Mount Mageik, although 

several lava flows on the volcano's east flanks are certainly post-glacial. The 1929 and 1936 reports may have 

been based on a very brief reference to "unusual activity" 

of Mount Mageik and other volcanoes in a newspaper 

account, and from reports of a ship's crew; the crew 

probably was no closer than 25 km to the volcano.

Composition

Sampled lava flows from Mount Mageik are all 

andesite or high-silica andesite containing 56 to 65 percent 

SiO2 (M.E. Yount, D.E. Kosco unpublished data; Hildreth, 

1987).

Volcanic activity

1927? 

1929? 

1936? 

1946?

Coats (1950) attributed 4 possible eruptions to Mount 

Mageik: in August 1927, in December 1929, in July 1936, 

and in 1946. The 1927 report is based on a Seattle 

newspaper's account of a report by a ship's captain who 

was sailing off the Alaskan Peninsula when Mageik 

supposedly erupted (Jaggar, 1927). The account mentions 

the ship was engulfed in ash and that fist-size pumice 

lumps were floating in the water. But the only pumice 

mantling Mount Mageik itself, is that of 1912 from 

Novarupta. Hildreth (1983) doubted the validity of the 

report and concluded that "...there are no credible reports 

of historical eruptions in the Katmai group except at

20
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE:

CAVW NUMBER:

MOUNT MARTIN

NONE

STRATOVOLCANO AND LAVA-FLOW FIELD

ABOUT 450 KM SOUTHWEST OF ANCHORAGE,

IN THE KATMAI GROUP OF VOLCANOES

58°10'N, 155°21'W

1860 M

MT. KATMAI

1102-14

Form and Structure

Mount Martin is located near the center of a high 

(>1400 m) ridge of altered basement rocks that extends 

more than 12 km, west-southwest from Mount Mageik 

(fig. 19) (Riehle and others, 1987). A crater, approximately 

300 m in diameter and breached on its southeast side, 

occurs high on the east side of the summit cone. The crater 

is the site of intense fumarolic activity and steam emission, 

and contains an ephemeral crater lake. The summit cone 

and the voluminous lava-flow field, which fill the upper 

valley of Angle Creek northwest of the volcano, which are 

of Holocene age. This flow-field, which erupted from a 

vent low on the north flank of the summit cone, covers 

approximately 31 km2 and has volume in excess of 5 km3 . 

Martin's extent has previously been overestimated because 

the young volcano lies adjacent to the glaciated remnants 

of a mid-Pleistocene andesitic edifice (Alagogshan 

volcano).

that time, mentioned only steam. Jaggar (1927) saw Mount 

Martin steaming on May 18, 1927 from a boat in Shelikof 

Strait. Muller, Juhle, and Coulter (1954) assumed that 

"ashfall at Kukak Bay on July 22, 1951, and the eruptions 

reported as occurring.. .in February, 1953" probably came 

from Mount Martin rather than Mount Mageik, apparently 

based on the relative volume of steam emissions observed 

from both during July 1953.

However, all reports of eruption or ash emission are 

probably spurious, reflecting only the persistent and 

conspicuous steam plume. Steam emission is normally 

vigorous and continuous from the summit vent of Mount 

Martin with plumes occasionally rising 600 m above the 

vent and extending downwind for 20 km.

Volcanic Activity

1913-1919?

1927, May 18?

1951, July 22

1953, February

1953 and 1954, summers?

Mount Martin, venting a prominent steam plume, was 

first photographed in 1913 but erroneously called Mt. 

Katmai (Griggs, 1922). In 1915, Griggs (1922) recognized 

that the mountain was an unknown, fumarolically active 

volcano west of Mount Mageik and named it in honor of 

George C. Martin, who was the first to visit and describe 

the Katmai area following the 1912 eruption.

Numerous reports of activity from Mount Martin are 

contained in the literature. Sapper (1927) reported strong 

"smoke" clouds from Mount Martin during the period 

1913-1919; Griggs (1922), who explored the area during see next page

21
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Composition

Information on the composition of Mount Martin is 

meager but it appears to consist chiefly of andesite and 

low-silica dacite lava flows (figs. 26, 27). The voluminous 

Holocene lava flow in Angle Creek is a high-silica 

andesite containing 62.5 percent SiO2 (M. E. Yount).

50 55 60 65 70 75 80

Figure 26. Total alkalies-silica diagram ofMt. Martin volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks (small 

dots) of continental affinity (those located east of 165°W 

longitude). Discriminant lines and field names (Le Bas and 

others, 1986) are explained on Figure 2.

O 5 

o>

0)

u. 3

45 50 55 60

SiO, WT.%

65 70 75

Figure 27. FeO/MgO-silica diagram ofMt. Martin volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks (small 

dots) of continental affinity (those located east of 165°W 

longitude). Tholeiitic versus calc-alkaline discriminant line from 

Miyashiro (1974).

22
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION: ALASKA PENINSULA;

LATITUDE, LONGITUDE:

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

MOUNT PEULIK VOLCANO

NONE

STRATOVOLCANO WITH SUMMIT AND FLANK DOMES

540 KM SOUTHWEST OF ANCHORAGE

57°45'N, 156°21'W

1474 M

UGASHIK

1102-13A

57°451 -

Form and Structure

Mount Peulik volcano, a small truncated 

stratovolcano with a basal diameter of about 10 

km, is located just north of the main axis of the 

Aleutian Range near Becharof Lake on the Alaska 

Peninsula (fig. 28). The volcano lies west of the 

axis of a northeast-striking syncline (Detterman 

and others, 1987) and is built upon Jurassic 

sedimentary rocks. The volcano partially overlaps 

the north flank of Ugashik caldera, a small 

circular structure about 5 km in diameter and of 

probable Late Pleistocene age. A summit crater, 

about 1.5 km in diameter, has been breached on 

the west side and is occupied by a dome about 

0.5 km in diameter. This dome, and possibly 

earlier predecessors, were the source of a thick 

deposit of block-and-ash flows that underlie about 

40 km2 of the western flank of the volcano. A 

smaller dome occurs on the east flank at an 

elevation of 1200 m and was the source of a small 

block-and-ash flow. Avalanche deposits representing an earlier sector collapse (Miller, in press) 

underlie an area of 75 km2 northwest of the 

volcano. Flows from flank eruptions of Peulik 

cover about 8 km2 north of the volcano extending 

as far as Becharof Lake.

Volcanic Activity [

1814 ^

1852 I

P

Coats (1950) cites only two reports of L 

historical activity that were apparently taken from 

Doroshin (1870) who stated that "around 1814 its 

[Peulik] summit collapsed with a rumble, covering the base with enormous boulders". This report may 

record an episode of dome destruction. Doroshin reported 

that in 1852 he saw only "smoke" coming from the south

1560 30' Contour Interval 1000 ft.

156°301 From Detterman and others, 1987

"V Holocene and Pleistocene

Holocene and Pleistocene

Surflclal deposits, undivided

Uklnrek maars

Block-and-ash flows

Volcanic avalanche deposits

Basalt and basaltic andeslte flows

High-silica andeslte and dacite flows

Volcanic domes

Volcanic rocks, undivided

Figure 28. Generalized geologic map of the Ugashik-Mount 

Peulik volcanic center after Detterman and others (1987).

side of the crater. No fumarolic activity was noted when 

the dome was examined in 1973.

23
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Composition

Mount Peulik volcanic rocks include calcalkaline 

flows, lava domes, and pyroclastic deposits (figs. 29, 30). 

Cone-building volcanic rocks are predominantly two 

pyroxene andesite with minor olivine basalt (Miller, in 

press); dome rocks and their associated pyroclastic-flow 

deposits are chiefly hornblende dacite and rhyodacite. 

Flank eruptions include basalt.

50 55 60 65 70

SiO, WT.%

75 80

Figure 29. Total alkalies-silica diagram of Peulik volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of 165"W longitude). 

Discriminant lines and field names (Le Bos and others, 1986) are 

explained on Figure 2.

8

7

6

O 5

O)

P 4

O

0) 

LL 3

2

1

45 50 55 60 65 

SiO., WT.%

70 75

Figure 30. FeO/MgO-silica diagram of Peulik volcanic rocks 

(solid circles) and other Aleutian arc volcanic rocks (small dots) 

of continental affinity (those located east of165°W longitude). 

Tholeiitic versus calc-alkaline discriminant line from Miyashiro 

(1974).

24
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

NAME AND LOCATION

NAME: UKINREK MAARS

N

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

Form and structure

Ukinrek Maars are a pair of phreatomagmatic 

explosion vents that formed on a low (less than 100 m 

high), 4-km-long, ridge in the Bering Sea Lowland 

1.5 km south of Becharof Lake and 12 km northwest 

of Peulik Volcano (fig. 28 [Peulik Volcano figure]). 

West Maar, elliptical in shape and up to 170 m in 

diameter and 35 m deep, formed on the northwest end 

of the ridge (Kienle and others, 1980). East Maar lies 

600 m east of West Maar at a lower elevation. It is 

circular, up to 300 m in diameter and 70 m deep, and 

has a 49-m-high central lava dome that is now partly 

covered by a crater lake. Location of the maars 

apparently coincides with, and may be controlled by, 

the intersection of the Bruin Bay fault and regional 

structures (Kienle and others, 1980; Detterman and 

others, 1983).

Volcanic activity

March 30-April 10, 1977

Ukinrek Maars were created during a 12-day 

violent eruption that began on March 30, 1977 (Kienle 

and others, 1980; Smithsonian Institution, 1977). 

Apparently, magma rose to the surface along deep 

intersecting structures and encountered ground water 

stored in a silicic pumice-rich pyroclastic deposit 

interbedded in glacial till (Self and others, 1980). West 

Maar formed first, during a period of phreatomagmatic 

explosions that generated steam and ash plumes to 

6500 m. Several days later, activity shifted from West 

Maar to a new crater (East Maar). During the next 

several days, strong phreatomagmatic explosions at 

East Maar spewed ash and steam clouds to 4000 m, 

initiated moderate base surges, and hurled blocks as far as 

600 m. Light ash fall occurred up to 160 km north. Near

NONE

MAARS

ABOUT 530 KM SOUTHWEST OF ANCHORAGE

ON ALASKA PENINSULA

57°50'N, 156°30'W

91 M

UGASHIK

1102-13B

Thickness of rim deposit 

25m

23m

17m

400m

EAST MAAR

100 Meters

From Kienle and others (1980)

Figure 31. Generalized map and cross-section of the eastern of 

the Ukinrek Maars from Kienle and others (1980).

the end of the eruption, Strombolian fountaining and dome 

building was observed as the magma degassed and 

vesiculated. By April 10, all activity had ceased except for

25
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

steaming from the lava dome as water flowed into the 

crater from the walls (Kienle and others, 1980).

Composition

Pyroclastic deposits associated with the 1977 eruption 

include juvenile ash, lapilli and blocks, stratified base 

surge deposits, and cognate and accidental lithic blocks 

(Kienle and others, 1980; Self and others, 1980). The rim 

deposit on East Maar consists of alternating layers of fine 

to medium grained tephra and black scoria with interspersed coarse lithic fragments. The deposit ranges in 

thickness from 11 m to 26 m (fig. 31). The juvenile 

Ukinrek ejecta are dark gray to black porphyritic olivine 

basalt (figs. 32, 33), which, like the CO2 that issues from 

nearby Gas Rocks (fig. 28), is mantle derived (Kienle and 

others, 1980; Barnes and McCoy, 1979). Cauliflower, 

spherical, and ribbon bombs are common and vesicularity 

of the ejecta ranges from scoria to dense lapilli, bombs, 

and blocks. Olivine is the dominant phenocryst phase; 

euhedral plagioclase laths (An?5) are the most common 

microphenocrysts (Kienle and others, 1980).

45

SiCL WT.%

Figure 32. Total alkalies-silica diagram of Ukinrek Maars 

volcanic rocks (solid circles) and other Aleutian arc volcanic 

rocks (small dots) of continental affinity (those located east of 

165"W longitude). Discriminant lines and field names (Le Bas 

and others, 1986) are explained on Figure 2.

8

7

6

O 5

en

O

0) U. 3

45 50 55 60

SiCL WT.%

65 70 75

Figure 33. FeO/MgO-silica diagram of Ukinrek Maars volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks (small 

dots) of continental affinity (those located east ofl65°W 

longitude). Tholeiitic versus calc-alkaline discriminant line from 

Miyashiro (I974).s.

26
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE:

ELEVATION:

USGS 1:250,000 QUADRANGLE:

CAVW NUMBER:

CHIGINAGAK VOLCANO

MOUNT CHIGINAGAK

STRATOVOLCANO

600 KM SOUTHWEST OF ANCHORAGE, ON THE

ALASKA PENINSULA

57°08'N, 157°00'W

2135 M

UGASHIK

1102-11

Form and structure

Chiginagak volcano is a symmetric composite cone 

about 8 km in diameter built on late Tertiary volcanic 

rocks and Jurassic-Cretaceous sedimentary rocks and 

located on a southwest trending regional anticline 

(Detterman and others, 1983). A deep breach on the south 

flank of the volcano extends to a small summit crater and 

exposes widespread alteration of interbedded lava flows 

and breccias near the summit of the volcano. Snow and ice 

cover much of the uppermost 1000 m of the cone.

Monolithologic breccias (vb) low on the west side of 

the volcano represent at least two early periods of dome 

growth and collapse, separated by a period of lava 

extrusion. The undissected form of the cone is the result of 

the eruption of andesitic lava flows and pyroclastic rocks 

(vu) following the emplacement of the youngest breccias. B7eo5. 

Somewhat younger andesite and dacite flows occur on the 

west flank and basalt flows (some as young as Holocene) 

occur on the eastern flank of the volcano. Satellitic dacite 

(?) domes of Holocene age occur high on the east and west 

flanks, the most recently active of which is the eastern 

dome which was the source of thin pyroclastic or epiclastic 

deposits (ba, fig. 34) that overlie nonglaciated basaltic lava 

flows.

Volcanic activity

1852? 

1929? 

1971?

156°55-

157*06' Modified from Dtttwmin and others 11987)

Miles

Kilometers

Alluvial, colluvlal, and 

glacial depoalta

Block and ash flow

Volcanic domat

Baaall and baaalllc 

andaalla flow*

Andealte and daclta flow*

]-HOLOCENE AND PLEISTOCENE

Volcanic rocks undivided

Volcanic braccla

Sedimentary and Ignaous rocks 1 TERTIARY TO PERMIAN

Hot spring

Documentation of any historical eruptions of 

Chiginagak volcano is sparse. The lack of any undisturbed 

ash or pumice deposits at or near the ground surface makes 

the reports of historic activity by this volcano somewhat 

suspect. Coats (1950) cites reports of smoke from 

Chiginagak in 1852 and unspecified activity in 1929; the 

1929 activity is based on a brief newspaper account of

Figure 34. Generalized geologic map ofMt. Chiginagak 

volcano after Detterman and others (1987).

"unusual activity" at Chiginagak and 6 other volcanoes 

observed by the crew of a ship which probably passed no 

closer than 25 km to Chiginagak. Mr. Odon Soeth reported 

observing an ash eruption in July, 1971 from Port Heiden,

27
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

100 km southwest of Chiginagak; according to Mr. Soeth, 

the eruption lasted only 1 evening. Steam and sulfur gases 

are constantly emitted from a vent high on the north flank 

of the volcano at about 1,520 m above sea level. Hot 

springs occur near the base of the volcano on the northwest flank (fig. 34). In late 1997 and 1998, this area of 

fumarolic activity became enlarged in a vertical direction.

Composition

The oldest recognized deposits of Chiginagak volcano 

are monolithologic, lithic pyroclastic deposits of dacitic 

composition. These are overlain by andesitic lava flows, 

which are overlain by a younger, lithic pyroclastic deposit 

composed of acid andesite. Two samples of post-glacial 

lava flows are basaltic.

Chiginagak lava flows generally display a porphyritic 

texture and contain phenocrysts of plagioclase (30-40%), 

clinopyroxene and orthopyroxene (15-20%) in approximately equal amounts, and rare, heavily oxidized 

subhedral hornblende. Silica contents of analyzed, 

hornblende-bearing samples range from 59% to 64%, 

waterfree (figs. 35, 36).

45 50

SiO. WT.%

Figure 35. Total alkalies-silica diagram of Chiginagak 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of continental affinity (those 

located east of 165°W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

O 5

D)

OCD U- 3 

2 

1

45 50 55 60 65

SiO2 WT.%

70 75

Figure 36. FeO/MgO-silica diagram of Chiginagak 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of continental affinity (those 

located east of 165°W longitude). Tholeiitic versus calcalkaline discriminant line from Miyashiro (1974).

28
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

ANIAKCHAK CALDERA

ANIAKCHAK CRATER

STRATOVOLCANO WITH SUMMIT CALDERA, INTRACALDERA DOMES, CONES, AND VENTS

670 KM SOUTHWEST OF ANCHORAGE ON THE

ALASKA PENINSULA

56°53'N, 158°10 W

HIGHEST POINT ON CALDERA RIM is 1,341 M;

VENT MOUNTAIN, HIGHEST INTRACALDERA CONE,

is 1,021 M

CHIGNIK

1102-09

Form and structure

Aniakchak Crater is an ice-free, 

circular caldera about 10 km in diameter 

and a maximum of 1 km deep (fig. 37) 

which was first described by Smith (1925). 

The pre-caldera cone was built upon a 

basement of Tertiary sedimentary and 

volcanic rocks and Jurassic-Cretaceous 

sedimentary rocks, which are exposed high 

on the east and south walls of the caldera 

(Detterman and others, 1981). The elevation of the caldera rim varies from 1,341 m 

to 610 m. Surprise Lake, a 3.2-km-long 

lake in the northeast part of the caldera at 

an elevation of about 335 m is the source of 

the Aniakchak River, which flows through 

a breach in the eastern wall of the caldera. 

Numerous domes, flows, and cones occupy 

the interior of the caldera (Neal and others, 

1992); the largest cone is Vent Mountain, 

2.5 km in diameter and rising 430 m above 

the floor of the caldera. The pre-caldera 

cone was built on the west side of a 

basement high. The cone was deeply 

dissected by numerous glaciers that cut Ushaped valleys into the slopes before the 

caldera-forming eruption.

Ash flows from the caldera-forming 

eruption 3430 + 10 yrs B.P. (Miller and 

Smith, 1987) reached both the Bering Sea and 

the Pacific Ocean (Miller and Smith, 1977). They 

are typically non-welded and fill glacial valleys to a 

depth of at least 75 m adjacent to the caldera rim. The 

ash flows were highly mobile, over-running 260-meterhigh passes in the Aleutian Range and travelling as far as 

50 km from the caldera rim (Miller and Smith, 1977).

«o<jme<J from DeStwroan and otftefft (196*5 18B7>

ALLUVIUM. COLLUVIUM, AND 

GLACIAL DE*»OS1TS UNDIVIDED

ASH FLOW AND 

ASH FALL DEPOSITS

UNDER AHQ SPATTER CWES

CALOERA RIM

EXPLOSION OCBRJS

OACtTE LAVA FLOWS

- HOfcOCENE

5 Wiles

9

Kitomelers

VOLCANIC ROCKS 

UNDIVIDED

SlfflMEWTAKV AND 

IGNEOUS ROCKS

AND 

PLEISTOCENE

}

Figure 37. Generalized geologic map ofAniakchak 

caldera, modified from Detterman and others (1987).

29
Volcanic activity 

1931

The only known historical activity at Aniakchak 

began at 10:00 a.m. on May 1,1931 with a series of 

violent eruptions that lasted until May 11,1931, another 

explosion occurring on May 20. No witnesses were at the 

volcano and the nearest observers were in the villages of 

Meshik (32 km away) and Chignik (70 km away). The 

manager of a cannery at Chignik reported that ash fell at a 

rate of "a pound per hour per square foot" (Jaggar, 1932). 

About half a centimeter of ash was deposited at Katmai 

National Monument and on Kodiak Island, and ash fall 

was reported as much as 480 km away over interior Alaska 

(Jaggar, 1932). The main source of the 1931 eruption is a 

low cinder and ash cone about a kilometer in diameter 

located near the base of the west caldera wall. A dome of 

blocky coarse-grained dacite was emplaced in the vent, 

probably in the waning stages of the eruption. At least two 

other sites along the southern wall and across the south 

flank of Vent Mountain were active during the 1931 

eruption (Neal and others, 1992).

Although no eruptions had been reported before 1931, 

Hubbard (1931) reported and photographed numerous 

fumaroles in the Half Cone region of the caldera (fig. 37). 

In 1973, temperatures of 80°C were measured at a depth of 

15 cm in loose volcanic rubble adjacent to the small cinder 

cone in the northwest part of the caldera 1.5 km northeast 

of the vent of the 1931 eruption. Springs near the northwest end of Surprise Lake had a temperature of 25°C in 

July, 1993. Although Hubbard (1931) concluded that the 

crater of Vent Mountain was still hot in 1930 based on the 

red color of the flows inside the crater, no activity was 

noticed by scientists who made a helicopter landing inside 

the crater in 1973; the red color was merely the result of 

oxidation of scoriaceous flows.

Composition

The pre-caldera volcano, which have been mapped 

and sampled only in reconnaissance, consist mainly of 

basaltic andesite, two-pyroxene andesite, and dacite (figs. 

38, 39). Phenocrysts of plagioclase, orthopyroxene, 

clinopyroxene, and less commonly olivine occur in a 

glassy groundmass of plagioclase and pyroxene microlites 

and magnetite euhedra.

The ash flows of the caldera-forming eruption range 

in composition from andesite to dacite with the SiO2 

content as high as 67.9%. Many ash flow outcrops are 

compositionally zoned with darker andesitic flows 

overlying lighter colored dacitic ash flows.

 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

The intracaldera volcanic rocks are predominantly 

glassy pyroxene dacite having SiO2 contents ranging from 

64.0 to 66.5%.

50 55 60 65 70 75 80

SiO2 WT.%

Figure 38. Total alkalies-silica diagram of Aniakchak 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of continental affinity (those 

located east of 165°W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

O 5

D)

P 4

O

0)

U- 3

45 50 55 60 65 

SiCL WT.%

70 75

Figure 39. FeO/MgO-silica diagram of Aniakchak 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of continental affinity (those 

located east of165°W longitude). Tholeiitic versus calcalkaline discriminant line from Miyashiro (1974).

30
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME: 

SYNONYM:

TYPE: 

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

MOUNT VENIAMINOF

VENIAMINOF CRATER

STRATOVOLCANO WITH A SUMMIT CALDERA

ABOUT 760 KM SOUTHWEST OF ANCHORAGE

ON THE ALASKA PENINSULA

56°10'N, 159°23'W

THE HIGHEST POINT ON THE CALDERA RIM IS

2507 M ABOVE SEA LEVEL

CHIGNIK

1102-07

Form and structure

Mount Veniaminof is a broad conical 

mountain, 35 km wide at the base, truncated 

by a spectacular steep-walled summit caldera 

8x11 km in diameter (fig. 40). The caldera is 

filled by an ice field that ranges in elevation 

from approximately 1750 to 2000 m; ice 

obscures the south rim of the caldera and 

covers 220 km2 of the south flank of the 

volcano. Alpine glaciers descend from the 

caldera through gaps on the west and north 

sides of the rim and other alpine glaciers 

occupy valleys on the north-, east-, and westfacing slopes of the mountain. In the western 

part of the caldera, an active intracaldera 

cone with a small summit crater has an 

elevation of 2156 m, approximately 330 m 

above the surrounding ice field. The rim of a 

larger but more subdued intracaldera cone 

protrudes just above the ice surface in the 

northern part of the caldera (not shown on 

fig. 40); based on limited exposure and 

physiographic features, it may have a summit 

crater as much as 2.5 km in diameter.

Andesitic and dacitic ash-flow tuffs 

from the caldera-forming eruption occur in 

many of the valleys on the north slope of the 

volcano and are found as far away as 50 km 

from the caldera rim on both the Bering Sea 

and Pacific Ocean coasts.

A northwest-trending belt of postcaldera cinder and scoria cones, including 

the two intracaldera cones, extends from near 

the Bering Sea coast approximately 55 km 

across the main volcanic edifice and the 

Aleutian Range divide, well down the Pacific 

slope (Detterman and others, 1981).

159-301 159°15'

56°20'

56°10'

[QU | Surficial deposits, Ice 

[ij|| Ash-flow and ash-fali deposits 

| cs | Cinder and spatter cones 

[df | Debris flow deposits 

|ijlef;| Dacite lava flows 

^^1 Andesite iava fiows 

K23 Volcanic rocks, undivided 

[TJj^l Sedimentary and Igneous rocks 

	x*^ Caldera margin

HOLOCENE

PLEISTOCENE AND HOLOCENE

JURASSIC TO TERTIARY

f\ Crater

Figure 40. Generalized geologic map of Mount Veniaminof volcanic 

center modified from Detterman and others (1981).

31
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Volcanic activity

1830-40?

August 4, 1838

1852

1874

1892

1930

May 23 - June 26, 1939

November 1939

March 28, 1944

March - May 1956

June 2, 1983 - April 1984

1993-1995

Mount Veniaminof's summit caldera formed 3700 

years B.P., sending ash flows 50 km toward the Bering Sea 

and into bays and estuaries on the Pacific coast (Miller and 

Smith, 1987). Historical reports of activity at Mount 

Veniaminof are often sketchy and second-hand. Father 

Veniaminof, after whom the volcano is named, reported 

"smoking" from 1830 to 1840 (Grewingk, 1850). Doroshin 

(1870) reported an ash eruption in 1838 and "smoking" in 

1852. Ball (1918) saw intermittent steam and black 

"smoke" puffs erupted during the summer of 1874. A 

violent ash eruption in 1892 was recorded by Davidson 

(1892) and Becker (1898). Hubbard (1931) saw ash 

explosions from the western intracaldera cone in 1930. On 

May 23, 1939, a series of explosions began that lasted 

until at least June 26, 1939; a U.S. Coast Guard cutter 

offshore reported an ash cloud to 6,100 m with 450 m high 

"flames". Ash from the eruption reportedly reached an 

average depth of 2-5 cm over a 84-km radius; most 

residents of Perry ville, 35 km south and directly 

downslope of the volcano, were evacuated. (Perry ville was 

established in 1912 by relocation of the former residents of 

the village of Katmai.) A mild ash eruption occurred on 

March 28, 1944 (Coats, 1950). Activity beginning in 

March 1956 culminated with ash explosions on May 19 

and 23, 1956 which sent ash-rich eruption columns to 

approximately 6,100 m according to airline pilot reports.

A moderate Strombolian eruption with accompanying 

lava flows began June 2, 1983 and lasted to mid-April 

1984, with a hiatus from mid-August to early October. 

Lava flows from the summit crater of the western intracaldera cone and adjacent subglacial activity melted -0.15 

km3 of the caldera ice field, forming a 0.9x2 km waterfilled ice pit approximately 120 m deep (Yount and others, 

1985; Yount and Miller, 1987). The ice pit subsequently 

was partially filled by an estimated 0.04 km3 of lava.

After a 9-year hiatus, a Strombolian eruption of ash 

and steam began on July 30, 1993 from the central cinder 

cone (Smithsonian Institution, 1993). An overflight on 

May 9, 1994 by Alaska Volcano Observatory personnel 

revealed a new oval-shaped lava field formed on the

southeast flank of the main intracaldera cone between 

1925 m and 1770 m elevation. The lava field extends 

about 1000 m in a north-south direction and about 800 m 

in an east-west direction and appears to have been chiefly 

fed from vents in the northern part of the lava field. Lava 

volume is estimated at 30-50 x 106 m3 . Intermittent 

emissions of ash and steam were observed and pilots 

reported a new steam vent in the icefield adjacent to the 

active cone, possibly resulting from a subglacial lava flow. 

Residents of nearby Perry ville reported a fiery nighttime 

scene in September, 1994, as incandescent material was 

ejected an estimated 300 m above the vent. Pilot reports 

and satellite imagery indicate sporadic activity continued 

well into 1995.

Composition

The pre-caldera volcano consists predominantly of 

andesitic and basaltic andesite lava flows (figs. 41, 42) 

with intercalated pyroclastic rocks; dacitic lava flows are 

minor. The ash flows of the caldera-forming eruption 

range in composition from andesite to dacite. Scoria 

collected inside the caldera and thought to be related to the 

active cone is basaltic andesite.

32
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

50 55 60 65 70

SiO, WT.%

75 80

Figure 41. Total alkalies-silica diagram ofVeniaminof 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of continental affinity (those 

located east of 165°W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

O 5

CD

? 4

O

Q)

U- 3

45 50 55 60

SiCL WT.%

65 70 75

Figure 42. FeO/MgO-silica diagram of Veniaminof 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of continental affinity (those 

located east of 165°W longitude). Tholeiitic versus calcalkaline discriminant line from Miyashiro (1974).

33
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

34
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

PAVLOF VOLCANO

NONE

STRATOvoLCANo

NEAR SOUTHWEST END OF ALASKA PENINSULA,

60 KM NORTHEAST OF COLD BAY

55°25'N, 161°54'W

2518 M

PORT MOLLER

1102-03

Form and structure

Pavlof Volcano is a largely snow-covered, 

cone-shaped mountain with a high ridge 

extending to the southwest towards the rim of 

Emmons Lake Caldera (fig. 43). The volcano is 

approximately 7 km in diameter and has active 

vents on the north and east sides close to the 

summit (McNutt and others, 1991). It is 

situated high on the northeastern flank of 

Emmons Lake caldera along a northeasttrending alignment of vents that includes Pavlof 

Sister, and several intracaldera cones (Kennedy 

and Waldron, 1955). The stratovolcano is 

relatively undissected and is mostly Holocene 

in age. Pavlof lies within the Shumagin seismic 

gap (Davies and others, 1981).

Volcanic activity

1790

1825

1838

1844

1846

1852?

1866

1880

1886

1892

1894

1906

1910-1911 

1914 

1917

1922

1923

1924

1929

1931

1936

1937

1942

1945

1947

1948

1950

1951

1953

1958

1962

1966

1973

1974

1975

1980

1981

1983

April 1986- 

August 1988 

Sept. 1996-

Jan. 1997

5 Kilometers

Contour Interval 1000 feet

Colluvium

Area covered by 1986 lahars

Pavlof flank flows

Pavlof Volcano is the most active volcano 

in the Aleutian volcanic arc with almost 40 

relatively well-documented eruptions dating 

back to 1790 (Newhall and Dzurisin, 1988; 

Smithsonian Institution, 1976-1988; McNutt, 

1987; Coats, 1950; Jaggar, 1932). It is so consistently 

active that a question sometimes arises as to what constitutes a separate eruption. Some Pavlof eruptions have been

Pavlof cone-building lava flows, Pavlof Sister lava flows, 

lahars, pyroclastic rocks lahars, pyroclastic rocks _

Emmons Lake lava flows, lahars, pyroclastic rocks

From McNutt, Miller, and Taber. 1989

Emmons Lake caldera rim

 

Seismic station

¥

Cinder cone

 

Fumarolic area

O

Vent

Figure 43. Generalized geologic map of Pavlof volcano 

from McNutt and others (1989).

short-lived (1-2 days duration) and similar eruptions in the 

past may have occurred unnoticed in the sparsely populated region.

35
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Pavlof eruptions are typically strombolian to vulcanian in character and consist of rhythmic ejection of 

incandescent bombs and ash to heights of 200-300 m 

above the summit (McNutt and others, 1991); spatter-fed 

lava flows emanate from the summit vents on occasion. 

Short-lived volatile-rich vulcanian ash columns reaching 

to heights of 10 km or more have been noted, usually at 

the beginning of an eruption. McNutt (1987) found a 

correlation between seismic activity and type of eruption. 

Strong volcanic tremor accompanied major strombolian 

magmatic eruptions, whereas episodes of explosion 

quakes, with little to no volcanic tremor, were diagnostic 

of minor phreatomagmatic events.

The largest historical eruption of Pavlof occurred on 

December 6-7, 1911 at the end of a five year period of 

activity. A fissure vent opened along the north flank, large 

blocks were ejected, and lava flows issued from the fissure 

(McNutt, 1987).

A recent vigorous eruptive period began mid-April, 

1986 and continued through August, 1988 (Smithsonian 

Institution, 1986-88; McNutt and others, 1991). Frequent 

steam and ash emission, explosions, and strong tremors 

accompanied summit lava fountaining that fed several 

agglutinate lava flows, which in turn produced a number 

of both hot and cold, "extensive mudflows. During the 

early course of the eruption, the eruptive vent shifted from 

the north to the east side of the summit.

The most recent eruptive episode at Pavlof Volcano 

began about September 11, 1996 and continued into early 

1997 (Neal and McGimsey, 1997). The eruptive activity 

was strombolian in character and similar to most Pavlof 

eruptions. Intermittent explosive activity and lava fountaining were recorded from two closely-spaced vents high 

on the northwest summit of the volcano. Incandescent 

spatter, spatter-fed flows, and small lahars moved down 

the northwest flank of the volcano for the next four months 

melting a narrow channel through snow and ice. Occasional elongate plumes that rose to a maximum of 10 km 

above sea level (generally less than 6 kilometers) and 

extended up to several hundred kilometers downwind were 

detected on satellite images and reported by pilots. These 

clouds consisted chiefly of vapor and gas with minor 

amounts of ash. Light ash fall was reported on several 

occasions from nearby communities.

Composition

Pavlof Volcano is composed of basaltic andesite lava 

flows (figs. 44, 45) and pyroclastic rocks that overlap 

similar rocks from nearby Little Pavlof. The flows are 

moderately phyric with about 25% phenocrysts, mostly 

plagioclase with minor olivine and clinopyroxene. The 

agglutinate flows of 1987 are of similar andesitic composition.

50 55 60 65 70 

SiO2 WT.%

75 80

Figure 44. Total alkalies-silica diagram of Pavlof volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of continental affinity (those located east of 

165° W longitude). Discriminant lines and field names (Le 

Bas and others, 1986) are explained on Figure 2.

7

6

O 5

D)

? 4

O 

o> 

u. 3

2

1

45 50 55 60

SiO, WT.%

65 70 75

Figure 45. FeO/MgO-silica diagram of Pavlof volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of continental affinity (those located east of 

165° W longitude). Tholeiitic versus calc-alkaline 

discriminant line from Miyashiro (1974).

36
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

Form and Structure

162°20'

Mount Button is a small snow-and icecovered calc-alkaline volcanic center with an 

approximate diameter of 5 km (not including the 

isolated large intra-canyon lava flow 5 km 

southwest of the summit) and an estimated 

volume of 7-15 km3 (fig. 46).The volcano is 

built on an east-sloping basement of hydrothermally altered Tertiary volcanic rocks (Kennedy 

and Waldron, 1955).

The volcano consists of a central multiple 

dome complex (Bavies and others, 1988) in 

which successive domes shouldered aside earlier 

domes and the enclosing cone-building volcanic 

rocks. Some hydrothermal alteration occurs 

along vertical contacts between adjacent domes. 

The dome-building activity and associated 

collapse has caused extensive destruction of 

cone-building lava flows and, to a lesser extent 

the domes themselves. This has resulted in the 

massive, thick-bedded debris flows 100-200 m 

thick that surround and mantle the central dome 

complex.

A headwall scarp about 300 m high and 

dipping to the northwest about 45° forms the 

west side of the summit. Bebris avalanches from 

this and lower areas moved down either side of 

the east-west oriented range crest. The resulting 

avalanche deposits include blocks up to 5 m in 

diameter and are characterized by hummocky 

topography and small closed depressions. The 

avalanche deposits cover a total area of about 

11.4 km2 and have an estimated volume of about 

0.17km3 .

MOUNT BUTTON VOLCANO

NONE

STRATOVOLCANO WITH SUMMIT DOME COMPLEX

SOUTHWEST TIP OF ALASKA PENINSULA 30 KM

EAST OF COLD BAY

55°11'N,1620 16'W

1473 M

COLD BAY

1102-011

andesite, locally 

hornblende - phyric

deposits 

dipping 10-15°

thick bedded,

very characteristic

coarse-grained hummocky

___ topography

Cone-building

andesitic flows;

glaciated

Moraine; Flank domes; |

represenls .

Alaska andesite '

(Holocene) I

glacialion I

Tertiary volcanic rocks

Unga-Belkolski Fm. 10-15 r

gran, intrus 5-10 m.y.

hydrothermally altered 

' debris flow cover

Approximate basement elevation 

based on Fe-rich spring location

Summit scarp

Direction ol avalanche

Only slightly dissected debris flows and 

pyroclastic flows occur on the east flank of the 

volcano. Two flank-domes occur 3.5 km north-northeast 

of the summit of Mount Button at an elevation of 520 m.

Figure 46. Geologic map of Mount Dutton volcano; 

mapped by T.P. Miller, C.A. Neal, and M.E., Yount.

37
 CATALOG or THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

These non-glaciated flank domes are assumed to represent 

Holocene eruptions. Most, if not all, of the avalanche and 

debris flows that mantle the volcano's flanks are also 

Holocene in age.

Volcanic activity

Although historical eruptions have not been reported 

from Mount Button, recent seismic activity suggests nearsurface magma movement which could be precursory to 

eruption. A swarm of shallow earthquakes during July and 

August, 1988, beneath Mount Button (Smithsonian 

Institution, 1988) sparked a volcano-seismic crisis. The 

activity was concentrated in three episodic sub-swarms 

with the largest event ML=4.0; many of these events were 

felt sharply at nearby communities, particularly King 

Cove, causing much concern. The distribution of epicenters forms a roughly linear zone which extends in a 

southeast direction about 10 km from the western shoulder 

of the volcano. The trend of the epicentral zone is parallel 

to the direction of maximum horizontal compression 

resulting from subduction of the Pacific plate and includes 

a prominent zone of hydrothermal alteration of the country 

rock. These similarities suggest that the seismic activity 

results from fracturing of the country rock as a dike is 

emplaced beneath Mount Button.

Composition

Mapping and sampling of the volcano has been 

preliminary only but the volcano appears to consist chiefly 

of calcalkaline feldspar-phyric andesite and subordinate 

dacite (fig. 47, 48) with SiO2 ranging from 55 to 63 

percent.

SiO. WT.%

Figure 47. Total alkalies-silica diagram ofDutton volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of continental affinity (those located east of 

165°W longitude). Discriminant lines and field names (Le 

Bas and others, 1986) are explained on Figure 2.

O 5

D>

? 4

O

o> 

u. 3

45 50 55 60 65 

SiO2 WT.%

70 75

Figure 48. FeO/MgO-silica diagram ofDutton volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of continental affinity (those located east of 

165°W longitude). Tholeiitic versus calc-alkaline 

discriminant line from Miyashiro (1974).

38
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

ISANOTSKI VOLCANO

ISANOTSKI PEAKS

STRATOVOLCANO

UNIMAK ISLAND, EASTERN ALEUTIAN ISLANDS,

ABOUT 80 KM WEST OF COLD BAY, ALASKA

54°45'N, 163°44'W

2446 M

FALSE PASS

1101-37

Form and structure

Isanotski volcano, located near the eastern end of 

Unimak Island, is a dissected, snow- and ice-covered 

stratovolcano with a basal diameter of about 10 km (fig. 

49). It is much more deeply eroded than neighboring 

Shishaldin volcano and lies between Shishaldin and 

Roundtop along a roughly 

east-west alignment. 164» 00 ,

Volcanic activity

1795 1830

1825 1845

Coats (1950) lists 

activity of Isanotski volcano 

as occurring in 1795, 1825, 

1830, and 1845; these 

eruptions are poorly documented and some or all may 

have occurred at neighboring 

Shishaldin volcano. For 

example, during an eruption 

of March 25, 1825, which is 

presumably that listed by 

Coats, "a low ridge on the 

northeast end of Ounimak 

[Unimak] opened in five 

places..." (Petroff, 1884, p. 

91); this description does not 

fit a central eruption of 

Isanotski volcano, although 

the proximity of the 

observer(s) is not known. 

Owing to an extreme degree 

of erosional dissection, 

historical eruptions of

Isanotski must be regarded as uncertain without further 

evidence; it is possible that historical fumarolic activity 

has served as the basis for reported activity.

Composition

Isanotski Volcano has not been mapped geologically 

and no description of its geology or composition is 

available.

163° 30'

54° 50'

-54° 40'

UNIMAK ISLAND Topography modified from 

U.S. Geological Survey 

Unimak (1:250,000 scale) 

False Pass (1:250,000 scale) 

Quadrangle maps

Figure 49. Topographic map of Isanotski Peaks and 

Shishaldin volcanoes.

39
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

SHISHALDIN VOLCANO

NONE

STRATOVOLCANO

UNIMAK ISLAND, EASTERN ALEUTIAN ISLANDS,

ABOUT 90 KM SOUTHWEST OF COLD BAY,

ALASKA

54°45'N, 163°58'W

2857 M

FALSE PASS

1101-36

Form and structure

Shishaldin Volcano, located near the center of Unimak 

Island, is a spectacular symmetrical cone about 16 km in 

diameter at the base. The mountain, which rises to a 

summit 2857 m above sea level (fig. 49), is the highest 

peak in the Aleutian Islands and has a small summit crater 

from which a steady cloud of steam is emitted. The upper 

2000 m is almost entirely covered by perennial snow and 

ice. It is flanked to the northwest by 24 monogenetic 

parasitic cones (Fournelle, 1988). The Shishaldin cone is 

less than 10,000 years old and is constructed on a glacially 

eroded remnant of an ancestral somma and shield 

(Fournelle, 1988), which in turn are underlain by 

volcaniclastic rocks of probable late Tertiary age (McLean 

and others, 1978). Fournelle (1988) suggests that the 

basement may consist, at least in part, of plutonic rocks.

Volcanic activity

1775-78

1790

1824-25

1827-1830

1838

1845 (1842?)

1865

1880-81

1883

1897-1899

1901

1912

1922

1925

1927-28

May-June 1929

Feb-May, 1932

Aug, 1946-Jan 1947

1948

July, 1955

Dec 28, 1963

Jan 28, 1967

Sept 13 (-Oct?), 1975

Apr-May, 1976

Feb 8, 1978

Feb 1979

March 1986-Feb 1987

December 1995-May 1996

Shishaldin, one of the most active volcanoes in the 

Aleutian volcanic arc, is situated near that part of the arc 

where the maximum rate of subduction occurs. At least 27

eruptions have been reported since 1775 with the latest 

occurring in 1995-1996 (Neal and McGimsey, 1997) 

(Jaggar, 1932; Coats, 1950; Went worth, 1951; Anchorage 

Daily News, July 14,1955; Anchorage Times, October 10, 

1975, September 26,1975, January 25,1976; Smithsonian 

Institution, 1978, 1979, 1986, 1987). Most, if not all, of the 

reported activity is strombolian ash and steam eruptions.

Major explosive eruptions occurred in 1830 (Coats, 

1950) and 1932 (Jaggar, 1932), and eight historical 

eruptions have produced lava flows (Smithsonian Institution, 1986). Steam and minor ash emission began in March 

1986 and continued intermittently through mid-February, 

1987.

A poorly documented short-lived eruption of steam 

and ash, perhaps as high as 10 km, occurred on December 

23, 1995 (Neal and McGimsey, 1997).

see next page

41
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Composition

Shishaldin Volcano has been mapped geologically at a 

reconnaissance level by Finch (1934) and Fournelle (1988) 

made a detailed study of the petrology of the volcano. 

According to Fournelle, the volcano is tholeiitic in 

character and predominantly basaltic (figs. 50, 51) with 

only a few compositions >53% SiO2 but with elevated 

TiO2 . Three main varieties are present: high magnesian 

basalt with -20% olivine and diopsidic clinopyroxene; 

porphyritic high alumina basalt with 30-45% plagioclase, 

<5% olivine, and rare clinopyroxene, and aphyric FeTi 

basalt with <20 % plagioclase and rare olivine. Recent 

lava flows are mostly high alumina, titanium-enriched 

basalt and high magnesium basalt (Fournelle, 1988). Older 

lava flows, possibly associated with the somma on the 

western flank are high magnesium basalt, daciterhyodacite, high alumina-titanium basalt and minor 

andesite (Fournelle, 1988). Salmon-colored pumice (64% 

SiO2) containing minor plagioclase and clino- and 

orthopyroxene occurs as recent tephra and in rare flowage 

deposits.

SiCL WT.%

Figure 50. Total alkalies-silica diagram of Shishaldin 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of continental affinity (those 

located east of 165°W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

o 5

O)

P 4

O

o> 

U. 3

2

1

45 50 55 60 65 

SiO2 WT.%

70 75

Figure 51. FeO/MgO-silica diagram of Shishaldin 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of continental affinity (those 

located east of 165°W longitude). Tholeiitic versus calcalkaline discriminant line from Miyashiro (1974). The two 

rhyolites have very high FeO*/MgO because of their very 

low MgO contents, and plot off the scale of this diagram.

42
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

FISHER CALDERA

NONE

CALDERA WITH POST-CALDERA DOMES, LAVA

AND PYROCLASTIC FLOWS

UNIMAK ISLAND IN THE EASTERN ALEUTIAN

ARC ABOUT 70 KM SOUTHWEST OF THE TIP OF

THE ALASKA PENINSULA

54°39'N, 164°26'W

1112 M MAXIMUM (CALDERA RIM); 183 M

(CALDERA LAKE)

UNIMAK

1101-35

164°3tf

Form and structure

Fisher caldera is II km wide by 18 km long, 

and has a maximum internal relief of 929 m. It is 

one of at least three volcanoes on Unimak Island 

that have been active in historical time.

The caldera is remarkable in size one of 

the largest calderas in the Aleutian arc and for 

the mobility of the ash flows that resulted from 

the caldera-forming eruption about 9100 years 

ago (Miller and Smith, 1977; 1987). The ash 

flows reached the Pacific Ocean 8 km to the 

southeast, and swept part way up the slopes of 

stratovolcanoes to the east and southwest 

(fig. 52). To the north, ash flows crossed 15 km 

of lowland to reach the Tugamak Range, 

surmounted drainage divides as much as 400 m 

above the lowland surface in the range, and 

continued northward an additional 8 km to the 

Bering Sea coastline. Miller and Smith (1977) 

inferred that the ash flows had unusually high 

velocities to cross such topographic barriers and 

suggested that the high velocities resulted by ash 

fall-back from a high eruption column.

Fisher caldera was the location of a large 

andesitic stratovolcano that was largely destroyed during caldera formation. Very little 

study has been done on the caldera itself. Postcaldera activity of Fisher caldera appears to 

consist of dome emplacement and eruption of 

lava flows and associated pyroclastic material, some of 

which may be historical in age (Miller and Smith, 1977).

164°3ff 

Outcrops of ash flows

Modified from Miller and Smith (1977)

Inferred original distribution of ash flows 

Arrows denote postulated flow direction

mountain pass

Figure 52. Generalized geologic map of Fisher caldera 

and vicinity after Miller and Smith (1977).

43
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Volcanic activity

1795? 1830? 

1826?

Veniaminov (1840, p. 19) described the activity of a 

volcano on the southwest side of Unimak Island, which is 

most likely that of Fisher caldera: "the low peak in the 

interior of Unimak Island, near its south end, burned until 

the upheaval of the southwest range [Westdahl], in 1795, 

then was extinguished. On October II, 1826, with a dull 

noise, it burst, emitting strong flames and a large quantity 

of ash. In August 1830, the summit of this peak exploded 

again, but without any other special phenomena.".

Active fumaroles occur in the central part of the 

caldera (Newhall and Dzurisin, 1988).

Composition

Juvenile pumice and scoria produced during the 

caldera-forming eruption ranged (figs. 53, 54) from 

basaltic andesite (52.5% SiO2) to dacite (65.4% SiO2) 

(Miller and Smith, 1977). Fournelle (1990) reported that 

pre-caldera volcanic rocks consist of aphyric andesitic 

(61% SiO2) pyroclastic rocks and lavas and some high Al 

plagioclase basalt. Post-caldera rocks include low Al 

porphyritic basalt.

50 55 60 65 70

SiO2 WT.%

75 80

Figure 53. Total alkalies-silica diagram of Fisher volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of continental affinity (those located east of 

165°W longitude). Discriminant lines and field names (Le 

Bas and others, 1986) are explained on Figure 2.

O 5

D)

? 4

OCD

U. 3

45 50 55 60 65 70 75

SiO2 WT.%

Figure 54. FeO/MgO-silica diagram of Fisher volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of continental affinity (those located east of 

165°W longitude). Tholeiitic versus calc-alkaline 

discriminant line from Miyashiro (1974).

44
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

WESTDAHL VOLCANO

WESTDAHL PEAK

UNCERTAIN; POSSIBLY A PYROCLASTIC CONE ON

A TRUNCATED ANCESTRAL STRATOVOLCANO OR

SHIELD

UNIMAK ISLAND, IN THE EASTERN ALEUTIAN

ARC ABOUT 85 KM SOUTHWEST OF THE TIP OF

THE ALASKA PENINSULA

54°31'N, 164°39'W

1560 M

UNIMAK

1101-34

Form and structure

Westdahl Peak, including nearby 

Paris Peak and Pogromni volcano, is 

located on a gently sloping plateau (mean 

elevation 1220 m) that may represent the 

surface of a truncated ancestral cone 

(fig. 55). Westdahl Peak is about 18 km 

in diameter at the base.

The size of the postulated ancestral 

cone is about 19 x 30 km at sea level, 

making it one of the largest volcanoes in 

the Aleutian Islands be it a stratovolcano 

or a shield. The entire ancestral cone has 

been extensively dissected by erosion, 

with the northeast-facing slopes steeper 

and of greater relief than the other slopes.

Based on the degree of erosional 

dissection, most of the postulated 

stratovolcano must have formed before 

early post-glacial time. Pogromni 

Volcano is moderately dissected and has 

broad valleys that have probably been 

glacially eroded. Such glacial erosion 

could have occurred during neoglaciation 

beginning about 3000 years ago (Black, 

1974, Table 1), although one or two 

thousand years seem inadequate to 

account for the degree of dissection. 

Pogromni volcano was probably active by latest Pleistocene time, which implies that truncation of the ancestral 

stratovolcano must have occurred earlier.

45'

-54° 30'

UNIMAK ISLAND Topography modified from 

U.S. Geological Survey 

Unimak (1:250,000 scale) 

Quadrangle map

Figure 55. Topographic map of Westdahl and Fisher 

caldera volcanoes.

45
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Volcanic activity

1795

1796 

1820 

1827-30

1964

Feb.3-9, 1978

Feb 8-9, 1979

Nov. 29, 1991 - mid. Jan. 1992

Veniaminov (1840, p. 18) described an eruption in 

1795 on the southwest end of Unimak Island, which most 

likely occurred at Westdahl. Coats (1950) attributed four 

eruptions in the late eighteenth century and early nineteenth century to Pogromni volcano. Based on recent 

observations from aircraft, however, Pogromni does not 

appear to have been active in historical time. The eruptions 

should probably be assigned to Westdahl. Known eruptions of Westdahl occurred in 1964 (Anchorage Times, 

March 11, 1964) and 1978 (Anchorage Times, Feb. 9, 

1978). The 1978 event lasted about six days (Feb. 3-9); ash 

fell on a ship 1000 km southeast of the volcano, and a 

mudflow extended down the flank of the volcano to the 

sea (Smithsonian Institution, 1978).

An apparent 8-km-high, 50-km-wide eruption cloud 

from Westdahl was observed on satellite imagery on 

February 8-9, 1979. However, no activity was reported 

from the U.S. Coast Guard station at Cape Sarichef, less 

than 25 km from Westdahl (Smithsonian Institution, 1979).

On November 29, 1991, pilots reported the beginning 

of a fissure eruption through the ice at Westdahl resulting 

in a lava flow approximately 3 km wide, 5-10 m thick, and 

about 7 km long extending down the northeast flank. 

Debris flows reached the sea 18 km from the vent. 

Dramatic lava fountaining and phreatic activity produced 

ash plumes that rose to 7 km altitude, prompting FAA to 

divert air traffic. Most of the ash was narrowly confined 

and remained at lower altitudes, dissipating harmlessly 

over the Bering Sea, however, light ashfalls occurred on 

Unimak Island including the village of False Pass, located 

90 km northeast of the vent. The activity declined in midDecember and had ceased by mid-January, 1992 

(Smithsonian Institution, 1991; 1992; McGimsey, 1995).

Composition

The volcano has not been mapped and little petrologic 

information is available. A few unpushed chemical 

analyses from USGS files indicate a range from basalt to 

dacite and tholeiitic character.

SiCX, WT.%

Figure 56. Total alkalies-silica diagram of Westdahl 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of continental affinity (those 

located east of 165° W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

8

7

6

O 5

en

P 4

O

£ 3 

2 

1

45 50 55 60 65 

Si0 WT.%

70 75

Figure 57. FeO/MgO-silica diagram of Westdahl 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of continental affinity (those 

located east of 165°W longitude). Tholeiitic versus calcalkaline discriminant line from Miyashiro (1974).

46
 CATALOG or THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

AKUTAN VOLCANO

AKUTAN PEAK

STRATOVOLCANO WITH CALDERA

WEST CENTRAL AKUTAN ISLAND, LARGEST OF

THE KRENITZIN GROUP, IN THE EASTERN PART

OF THE ALEUTIAN ISLANDS AND ABOUT 185

KM SOUTHWEST OF THE TIP OF THE ALASKA

PENINSULA

54°08JN, 165°58'W

1303 M

UNIMAK

1101-32

Form and structure

Akutan volcano is a composite stratovolcano with a 

circular summit caldera about 2 km across and 60 to 

365 m deep (Byers and Earth, 1953; Romick and others, 

1990; Motyka and others, 1981) (fig. 58 A, B) and an 

active intracaldera cinder cone. The caldera rim reaches 

a maximum altitude of 1303 m at Akutan Peak, the 

remnant of a pre-caldera cone now filled with a lava 

plug. The caldera is breached to the north. Caldera 

subsidence accompanied or followed eruptions from a 

series of rim vents. The vestige of a larger caldera, of 

probable late Pleistocene age and at least in part older 

than the cone of Akutan Peak, extends 1.5 km southwest 

of Akutan Peak and is terminated to the north by the 

younger caldera. Small glaciers fill the older crater and 

lie within the southwest and southeast margins of the 

younger caldera.

The active intracaldera cinder cone is over 200 m 

high, about 1 km in diameter, and located in the northeast quarter of the caldera. Three small sulfur-lined 

craters occupy its summit and several fumarole zones are 

present along its south and southwest flank (Byers and 

Earth, 1953). A crescent-shaped lake along the inner 

southwest rim of the caldera and a hot and slightly acidic 

lake along the northern caldera wall were noted by Byers 

and Earth in 1948 but Motyka and others (1981) 

speculate that these lakes may have been obliterated by 

more recent activity. Both lakes drained to the north 

through a gap in the caldera wall.

The lava flows and pyroclastic deposits of Akutan 

volcano are no older than Pleistocene as Romick and 

others (1990) report ages of l.ltO.l to 1.8±0.8 Ma for 

the oldest of these rocks. The caldera-forming eruption 

occurred about 5,200 yBP (Reeder, 1983) and was the 

source of small volume andesitic pyroclastic-flow

Contour Interval 1000 toot oxcopt 

where dashed, SCO loot

Modified from Finch (1935)

Crater Gap Crater wall and 

ipproximate location of 

",'-!"/: v crater fault

(site of old crater)

Recent, pre-1947 lavas

Glacial moraine

-crater ash and 

agglomerate

Pre-crater lava 

and intrusives

Fumarole zone

AKUTAN CRATER and Barth (1953)

Figure 58. Topographic map of Akutan island (A) and 

geologic map of Akutan volcano (B) after Byers and Barth 

(1953).

47
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

deposits in valleys on the north, south, and east sides of the 

volcano (Miller and Smith, 1987; Romick and others, 

1990). Young basaltic lava flows, some of which were 

erupted in 1929, cover the caldera floor south and north of 

the cinder cone and extend several hundred m downslope 

through the crater rim gap. Flows extruded in 1947 blanket 

the central portion of the northwest end of the island at 

Lava Point, where about 4 km2 of jagged aa basalt occurs 

adjacent to several cinder cones. The entire island is 

mantled by an ash layer that thickens toward Akutan Peak; 

landslide and mud flow deposits have concentrated this 

ejecta in the valleys north and northeast of the caldera and 

a maximum fill depth of 7 m occurs at Wooly Cove (Finch, 

1935).

Active hot springs occur northeast of the caldera at the 

head of Hot Springs Bay valley and along the shore of Hot 

Springs Bay; Byers and Barth (1953) and Motyka and 

others (1990) recorded temperatures between 67 and 84°C 

and a pH range of 6.6 to 7. Surface waters of the hot 

caldera lake were 50°C with a pH of 5.0 and steam issuing 

from fumaroles along the cinder cone base averaged 96°C 

(Finch, 1935).

Volcanic activity

1790 1892

1828 1896

1838 1907

1845 1908

March, 1848 1911

1852 1912

1865 1928

Apr 29-Aug ? 1948 

Oct., 1951 

1953

March-May, 1973 

Feb. 11, 1974

Oct. 15, 1976-May, 1977 

Sept.-Oct., 1978

1867 Dec (May?) 1929 July 8, 1980 

1883 May-Aug 1931 Jan. - March, 1987 

1887 Dec., 1946- June, 1987

Jan., 1947 March - April, 1988 

March - May, 1992

Akutan is one of the most active volcanoes in the 

Aleutian arc. At least 27 separate episodes of volcanism 

have been noted since 1790 and it is likely that additional 

events have gone unrecorded due to the remoteness and 

sparse population of the island. Moreover, Akutan frequently produces low-level eruptive activity including 

steam and ash emission.

Few details are available concerning early Akutan 

volcanism (Finch, 1935; Byers and Barth, 1953; Simkin 

and Siebert, 1994). Vigorous activity was reported along 

the northwest flank of the main cone in 1852; a pyroclastic 

eruption in 1911 deposited ash as far east as Akutan 

village, 13 km from the volcano summit. Some of the 

flows at Lava Point may have formed in the late 1920's 

when C. Anderson, captain of the mail steamer Starr, 

observed smoke near Lava Point, which may have issued 

from a large cinder cone at the base of Half Peak. Much of

the Lava Point lava field, however, may have originated 

before 1870.

Other twentieth century events within Akutan caldera 

are better documented. In 1929, lava was observed flowing 

through the breach in the north caldera rim and extending 

about 0.7 km down the northeast flank. A mudflow 

produced at the front of this lava tongue flowed into 

valleys to the north and northwest. "Dark smoke" was 

noted above the caldera cinder cone in 1931.

Lava extrusion resumed in early 1947 from a vent 

near the base of the caldera cone. Navy vessels evacuated 

75 island residents on January 5th, but the flow was 

confined to the center of the caldera. Three earthquakes 

preceded a major eruption on April 29, 1948, which 

covered Akutan village with measurable deposits of ash 

(Alaska Sportsman, 1949). Activity continued full scale 

until mid-May, and in August of that year, clouds of ashladen gas and incandescent fragments up to 1 m in 

diameter were still being ejected at intervals of 1 to 5 

hours from the summit cone . Dark-grey cauliflowershaped clouds rose 1.6 km above the cone and explosions 

were heard at Akutan village. Ash eruptions continued to 

be reported until 1953.

More ash eruptions occurred in 1973 and 1974; in 

May, 1977, clouds of light brown ash were ejected about 

every 15 minutes, with intervening periods of steam 

emission. Activity was renewed in late September, 1978; 

airline pilots observed incandescent fragments, some "as 

big as a car", ejected 100 m above the summit, and a lava 

flow along on the slopes of the main cone. This flow may 

have gone through the north breach of the caldera rim. 

Minor ash and steam were observed in 1980.

Emission of steam and ash were reported from 

January through early March, 1987. Following a lull in 

activity between March and early June, the eruption 

resumed in late June; a 300-m-high steam plume, ash 

blackened snow, and an orange glow at the summit were 

observed. Further activity was reported in March, 1988 

when small ash eruptions began from the summit cinder 

cone and continued intermittently through July, 1988. 

During this eruption cycle, ashfall and strong sulfur fumes 

were reported on several occasions at Akutan village, 12.5 

km east of the volcano.

From August 1988 to February 1989, only steam 

emissions were reported. During February and March 

1989, ash and steam emissions resumed from the summit 

tephra cone. Akutan village reported a light dusting of ash 

on March 16. Activity then subsided until September 1990 

when a brief period of intermittent emission of small ash 

and steam plumes occurred. A two-month period of 

intermittent steam and ash emission began again in 

September 1991. The most recent eruptive activity from

48
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Akutan was during March through May 1992 and possibly 

into 1993 when localized steam and ash emissions with 

plumes rising up to 4600 m were reported. The mild 

sporadic Strombolian eruptive activity of the early 1990's 

suggest that a magma column may have been in the central 

vent conduit for much of this time.

An intense earthquake swarm began beneath Akutan 

volcano in the eastern Aleutian Islands on March 10, 1996 

causing apprehension in the nearby village of Akutan that 

an eruption might be eminent. About 7:30 PM (AST) on 

March 10, residents of Akutan reported feeling almost 

"continuous" earthquake activity, punctuated by frequent 

strong shocks. This earthquake swarm continued through 

most of March 11 before beginning to subside about 5:00 

PM (AST). At the peak of the swarm, earthquakes were 

being felt every few minutes and over 40 events/hour were 

recorded on Button volcano stations 300 km to the east.

Seismic activity continued to decline through March 

12 with felt events reported at the rate of about 1 per hour. 

This decreased level of activity continued until about 5:00 

PM (AST), March 13, when another intense earthquake 

swarm began. Felt earthquakes were occurring at the rate 

of about 1 per minute, similar to the rate reported on 

Monday, March 11 and ~ 30 events/hour were recorded at 

Dutton. This second earthquake swarm continued until 

about 7:30 PM March 14 when it began to decline.

Although most of the earthquakes were small, at least 

3 had magnitudes between 5.0 and 5.3. The strongest 

earthquakes were felt in Dutch Harbor some 50 km to the 

west. Some damage was reported including cracks in 

walls, objects falling off shelves, and cracked plumbing.

The seismicity continued to decline over the next 

week although still remaining at relatively high levels. 

Recorded earthquakes declined from over 800 a day on 

Thursday and Friday, March 14-15, to about 60 per day by 

March 22.

Almost all of these earthquakes are volcanic-tectonic 

(VT) or tectonic events and were chiefly located on the 

northeast flank and east of the volcano with the suggestion (?) of a NW-SE trend over the known thermal areas.

The frequency, size, and duration of the seismic 

activity suggests magma movement beneath the volcano.

Composition

Relatively little information has been published on the 

composition of modern Akutan volcano; the report of 

Byers and Barth (1953) covered only the products of the 

1946-1948 eruptions. Romick (1982) recognized two 

petrologic groups: olivine-clinopyroxene basalt from the 

western part of the island, and clinopyroxeneorthopyroxene andesites exposed elsewhere on the island. 

Romick et al (1990) did a more detailed study of the 

composition of ancestral volcanic rocks and included two 

analyses of lava from the modern Akutan cone and one 

from the sea level lava field (Lava Point) at the west end 

of the island. The samples are porphyritic 2-pyroxene 

andesite (55.-57.8% SiO2) in the case of Lava Point and 

plagioclase-augite-olivine andesite in the cone lavas.

Lava extruded in January of 1947 and a block ejected 

in August of 1948 are both porphyritic basalts containing 

about 30% plagioclase phenocrysts (An47 -An70), minor 

augite and sparse hypersthene, olivine and magnetite 

grains in a complexly intergrown groundmass of calcic 

andesine, pyroxene, ilmenite and magnetite (Byers and 

Barth, 1953).

Figure 59. Total alkalies-silica diagram of Akutan volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of oceanic affinity (those located west of 

165°W longitude). Discriminant lines and field names (Le 

Bas and others, 1986) are explained on Figure 2.

continued 

___49
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Pyroclasts up to 3 mm in diameter were also produced 

during the 1947 and 1948 eruptions and deposited as 

tephra. Scoriaceous fragments composed of plagioclase 

and augite phenocrysts in a matrix of light brown glass 

constitute most of this material (Byers and Earth, 1953, p. 

391).

Pre-1932 flows were examined by Finch within the 

caldera and at Lava Point; all were considered "normal 

basalts" (Finch, 1935, p. 159).

O 5 

en

O 

IJL 3

2

1

45 50 55 60 65 70 75

SiO2 WT.%

Figure 60. FeO/MgO-silica diagram ofAkutan volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of oceanic affinity (those located west of 

J65°W longitude). Tholeiitic versus calc-alkaline 

discriminant line from Miyashiro (1974).

50
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

MAKUSHIN VOLCANO 

NONE

STRATOVOLCANO WITH CALDERA AND PARASITIC 

CONE

UNALASKA ISLAND, ABOUT 250 KM SOUTHSOUTHWEST OF THE TIP OF THE ALASKA

PENINSULA

53°53'N, 166°56'W 

1800 M 

UNALASKA 

1101-31

Form and structure

Makushin volcano is a broad, truncated 

stratovolcano, 1800 m high and 16 km in 

basal diameter, which occupies most of the 

triangular northwest extension of Unalaska 

Island (fig. 61). A breached summit caldera, 

about 3 km across, contains a small cinder 

cone, eroded remnants of other cones, and 

several fumaroles. The volcano is capped by 

an icefield of about 40 km2 ; subsidiary 

glaciers descend the larger flanking valleys 

to elevations as low as 305 m.

Makushin volcano was constructed 

during two periods of volcanism separated 

by an interval of pronounced erosion 

(Drewes and others, 1961). Bedrock is 

exposed as high as 975 m on the southeast 

flank of the volcano. The first episode began 

in Pliocene or early Pleistocene time (the 

oldest known age of lavas is 0.93 Ma [Nye, 

1990]) and produced extensive flows and 

subordinate pyroclastic deposits of basaltic 

and andesitic composition (fig. 61), which 

enlarged the island by several kilometers 

along the northwest coast. Radial dips of 

flows suggest that Makushin Volcano itself 

was the principal vent area. The older flows 

are extensively glaciated, which implies a 

minimum age of late Pleistocene. The 

summit of Makushin subsequently collapsed, 

forming a caldera. Andesitic pyroclastic-flow 

and debris flow deposits occur in glaciated 

valleys on the north and south sides of the 

volcano indicating a Holocene age for the caldera-forming 

eruption Miller and Smith, 1987). Reeder (1983) reported 

a 14C age determination of 7950 ± 90 ybp on organic soil

BERING SEA

Pt. Kadin Vent

Contour Interval 1000 feel

I A I

[Qvp | Pyroclastic deposits

After Drewes and others. 1961, and Nye. 1986

Post-caldera basalt and andesitic 

flows and scoria

Pre-caldera basalt and andesite flows 

and pyroclastic deposits

Granodiorite batholith

Unalaska Formation

Figure 61. Generalized geologic map ofMakushin volcano after 

Drewes and others (1961) and Nye (1986).

directly beneath the pyroclastic flow deposits and Nye and 

others (1984) report a limiting 14C age of 4280 ± 280 ybp 

on organic material in a debris flow.

51
Several monogenetic satellitic vents composed of 

basaltic and andesitic lava flows, ash, and scoria cones 

occur within the summit caldera. These vents also form 

smaller cones on Makushin's flanks and surrounding area. 

Most of these vents have been slightly glaciated but 

blanket late Pleistocene topography indicating a latest 

Pleistocene or early Holocene age. Pakushin cone, a 

multiple-cratered composite cone, lies 8 km southwest of 

Makushin Volcano. Tabletop Mountain, the eroded 

remains of a pyroclastic cone encircled by flows originating from small flank vents, is 20 km northeast. Wide Bay 

cone, a small symmetric cone with an oval summit crater, 

occupies the northwest edge of Unalaska Bay, and 

Sugarloaf cone, built of steeply dipping, crudely bedded 

pyroclastics, is situated 14 km to the southwest. The Point 

Kadin vents, 10 small cones and explosion craters aligned 

along a rift zone trending N 75° W from the summit 

caldera, lie just south of an ash-flow deposit which fills a 

valley extending north from the volcano to the coast. The 

deposit is relatively undissected and may correlate with a 

blanket of airfall ash and cinders that covers part of the 

icefield on the volcano's northern flank. Based on geomorphic analysis, Arce (1983) infers that the sequence of 

Holocene events to have been as follows: construction of 

Sugarloaf cone, activity at Tabletop Mountain, construction of Makushin cone, and lastly, construction of the Wide 

Bay cone and activity on the Pt. Kadin vents.

Arce (1983) concludes that at least 15 tephra layers of 

Holocene age are recognizable on northern Unalaska 

Island; however, he assigns some to satellite vents of 

Makushin Volcano and others to more distant sources, so 

the exact number of deposits attributable to Makushin 

Volcano is uncertain.

Volcanic activity

1768-1779 1845

1790(1792)? 1865

1802 1867

1818 1883

June, 1826 1907

1827-38 1912

Dec. 1926 

Oct. 1938 

Dec. 20, 1951 

1952 

1980

Makushin Volcano has been reported active since its 

discovery in 1763 by Russians under the command of 

Korovin, but no major eruptions have occurred since 1826 

(see Coats, 1950, Table 2). Powers (1958) lists an ash 

eruption in 1951 and smoke in 1952. Drewes and others 

(1961) conducted field studies of Unalaska Island in 1953- 

1954; during this period, vigorous solfataric activity was 

noted in and adjacent to Makushin's summit caldera. 

Several fumaroles bordering the main vent emit a mixture 

of water vapor, H2S and SO2 ; temperatures as high as 

154°C have been recorded and the heat of the escaping 

gases keeps the center of the caldera free from ice. A 

minor explosive eruption from a small vent on the south

 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

flank may have occurred in the spring or early summer of 

1980 (Smithsonian Institution, 1980).

Two smaller regions having superheated fumarole 

activity occur in northwestern Unalaska Island. One is 4.8 

km southeast of Makushin's summit vent, and the other is 

3.2 km to the south. Hot springs are found at these sites, as 

well as near Summer Bay, 32 km east of Makushin.

Composition

The Pleistocene lavas are dominantly basalt and 

basaltic andesite (figs. 62, 63) but include some andesite 

and dacite (Nye, 1990, Drewes and others, 1961). Early 

Holocene lavas have a wide compositional range and are 

generally more silicic than the Pleistocene lavas. Late 

Holocene lavas mark a return to more mafic compositions.

Older flows are 3 to 15 m thick. Flow breccias and 

thin ash beds are the main pyroclastic deposits. Thicker, 

massive pyroclastic deposits occur locally. Flow rocks are 

commonly porphyritic with felted or fluidal groundmass 

textures. Phenocrysts include plagioclase (most commonly 

labradorite), augite, hypersthene, and rare olivine. Accessories include opaques, apatite, zircon, and very rare 

amphibole and cristobalite. A few small hypabyssal bodies 

of basaltic, andesitic, and dacitic compositions intrude the 

older Makushin volcanics.

Younger volcanics are cinder cones, volcanic mud 

flows, and lava flows that retain much of their primary 

morphology. Porphyritic, felted or fluidal textures are 

dominant in flow rocks, and vugs and vesicles are common. Flow thickness are similar to those of the older 

volcanics. Phenocrysts include sodic bytownite or labradorite, augite, olivine, and in some samples hypersthene.

52
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Si02 WT.%

Figure 62. Total alkalies-silica diagram ofMakushin 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of 165°W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

7

6

O 5 

o>

? 4

O 

£ 3

2

1

45 50 55 60 65 70 75

SiO2 WT.%

Figure 63. FeO/MgO-silica diagram ofMakushin volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of oceanic affinity (those located west of 

165°W longitude). Tholeiitic versus calc-alkaline 

discriminant line from Miyashiro (1974).

53
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

BOGOSLOF VOLCANO

BOGOSLOF ISLAND

S TRATO VO LCAN O

BOGOSLOF ISLAND, 43 KM NORTH OF UMNAK

ISLAND AND ABOUT 312 KM WEST-SOUTHWEST

OF THE TIP OF THE ALASKA PENINSULA

53°56'N, 168°02'W

101 M (U.S. COAST AND GEODETIC SURVEY,

1947); 150 M (HARBIN, 1994)

UMNAK

1101-30

Form and structure

Bogoslof Island is the largest of a cluster of small, low 

lying islands that comprise the emergent summit of a large 

submarine stratovolcano that rises more than 1500 m 

above the Bering Sea floor (Byers, 1959, plate 39). The 

volcano appears to be a back-arc feature as it occurs well 

behind the volcanic front of the main Aleutian arc. The 

island has undergone dramatic changes in size and shape 

during historical time, an evolution that has been unusually 

well observed and recorded for such an isolated volcano.

The island is presently shaped like an irregular 

isosceles triangle about 2.0 km long and 0.75 km wide 

covering an area of 0.75 km2 (fig. 64). Castle Rock, a 

steep, twin-spired pinnacle along the southwest side of the 

island is the eroded remnant of a dome extruded in 1796. 

Vent agglomerate produced during the explosive phase of 

that eruption lies in fault contact with the dome material 

and is best exposed in the southeast part of the sea cliff 

below Castle Rock.

A blanket of basaltic agglomerate and ash is plastered 

against the steep north and east flanks of Castle Rock and 

extends north and east as a broad terrace. This material is 

interpreted by Byers (1959) to have been deposited 

primarily during the 1926 eruption but may also be from 

earlier Bogoslof eruptions. The tephra layer, along with a 

basaltic dome extruded in early 1927, comprises most of 

the area of the island, which is steadily being reduced by 

marine erosion. The 1927 dome is a rounded knob more 

than 40 m high and 305 m in diameter on the northwest 

coast, and fronts an arcuate salt water lagoon to the east. 

Cobble-boulder beaches fringe the island's north and 

southeast shores and a sand beach extends along the 

eastern margin.

168° 03' 

 I 

168° 02'

Fire Island

- 53° 56' 02"

Contour interval 20 feet 

100 feet at steep cliffs

- 53° 56' 00"

-53° 55' 58"

From Byers, 1959

Beach deposits

Basaltic ash and 

agglomerate of 1926

Basaltic dome 

of 1927

Hornblende basalt of 

Fire Island (1883)

Hornblende andesite of Vent 

Castle Rock (1796) agglomerate 

(1796)

 Fault, dashed where Inferred 

U

Figure 64. Generalized geologic map of Bogoslof island 

modified from Byers, (1959).

54
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

About 610 m northwest of Bogoslof lies Fire Island, a 

tiny flat-topped stack resembling a lighthouse. The island 

is the remnant of a dome extruded in 1883. Domes 

produced during other episodes of Bogoslof volcanism 

have been completely destroyed through subsequent 

explosive eruption and marine erosion.

Volcanic activity

May 1796-1804 Jan. 1907- 

Sept. 19 1806-1823 Sept. 1909-1910 

Sept. 27, 1883 (1882?) - 1895 July 1926-1931 (?) 

March 1, 1906-Jan. 1907 (?) Sept. 1951

July 1992

A small rocky prominence, called Ship Island or Ship 

Rock, was observed in 1768 by Russian explorers at the 

approximate site of Bogoslof Island; it disappeared 

through marine erosion by the end of the 19th century and 

little is known concerning its composition and origin 

(Byers, 1959). An explosive eruption of debris in 1796, 

followed by extrusion of viscous lava, built a second 

island by 1804, about 0.6 km south of Ship Rock. The 

second island was known successively as loann Bogoslof, 

Old Bogoslof and Castle Rock. The vent agglomerate and 

hornblende andesite of Castle Rock, exposed on the 

southwest end of modern Bogoslof Island, represent early 

and late products, respectively, of this eruption (Byers, 

1959). Russian-American Company personnel on Umnak 

Island reported three days of earthquakes and brilliant 

flames during the creation of the loann Bogoslof, and 

almost eight years elapsed before it had cooled sufficiently 

to permit first-hand examination (Henning and others, 

1976). In 1806, lava flowed from the summit north into the 

sea creating new land and increasing the summit altitude. 

This increase in size and altitude appears to have ended in 

1823, when the dome had a pyramidal form at least 110 m 

high (Byers, 1959).

In 1882, Unalaska residents noticed steam rising from 

the ocean about 2 km north of Ship Rock (Byers, 1959). 

On September 17, 1883, a volcanic dome was first 

observed at this site, and one month later a violent eruption 

deposited ash on the village of Unalaska, 96 km to the 

east. The new island was called Grewingk or New 

Bogoslof; its erosional remnant is now designated Fire 

Island. In 1884, the cone (presumably the dome was 

destroyed) had a diameter of about 1 km, a craggy profile, 

and pinnacles that reached an altitude of about 150 m 

(Byers, 1959). In May of that year, officers of the Revenue 

Marine steamer Corwin examined the Bogoslof group. 

They found Ship Rock, Old Bogoslof and New Bogoslof 

connected into a single land mass by bars of volcanic 

debris and sand-boulder beaches. Second Lieutenant J.C. 

Cantwell observed 15 separate vents on the upper third of 

New Bogoslof cone issuing jets of steam with great force 

and regularity; thick sulfur deposits surrounded most of

the vents, and the temperature in a crack near the summit 

was estimated to exceed 260°C. Great quantities of fine 

ash coated the slopes, but little coarse ejecta or flow lava 

was encountered (Henning and others, 1976). In 1895, 

New Bogoslof was still steaming vigorously, and was a 

flat-topped structure about 90 m high, separated by several 

hundred meters of open water from Old Bogoslof. By 

1897 New Bogoslof had cooled (Byers, 1959).

In 1906, a dome bearing a broken spire at its summit 

appeared midway between Old and New Bogoslof. This 

structure, called Metcalf Cone, exploded in late 1906 or 

early 1907, destroying its southern extent, but soon 

thereafter another dome emerged, joining Metcalf Cone 

and Old Bogoslof (Byers, 1959). This dome, McCulloch 

Peak, was subsequently obliterated in a violent explosion 

on September 1,1907 that showered Unalaska village with 

0.5 cm of ash and mantled the remaining Bogoslof islands 

with debris. Yet another conical islet, Tahoma Peak, was 

formed during the winter of 1909-1910 in the bay created 

by the destruction of McCulloch Peak. Explosions in 

September of 1910 produced a deep crater at its summit 

(Byers, 1959); this was apparently the first documented 

crater in a Bogoslof dome (Jaggar, 1930).

By 1922 the last vestiges of Metcalf Cone and 

Tahoma Peak had been removed through continued 

explosions, collapse, and marine erosion (Byers, 1959). 

New Bogoslof (now called Fire Island by the U.S. Coast 

and Geodetic Survey) was reduced to a small islet, and Old 

Bogoslof (Castle Rock) to two rocky horns. Renewed 

submarine explosions between the two islands in 1926 

produced another conical dome by early 1927. A tephra 

ring, located about 3 m above high tide, surrounded the 

new dome and connected it to Fire Island and Castle Rock, 

thus forming a single elongate island. By July, 1927, the 

circular dome was 60 m high and 300 m across and was 

circled by a shallow lagoon of warm water. On October 

31, 1931, the dome was still incandescent, and floating 

pumice was observed south of the island (Byers, 1959, p. 

361). By 1935 an open water strait again separated Fire 

Island from the larger southern island; the southern island 

was then officially called Bogoslof and comprised Castle 

Rock, the pyroclastics produced in 1926, and the dome 

formed in 1927. A possible submarine eruption or landslide occurred in September, 1951 when a vessel traversed 

3 km of "muddy water" adjacent to Bogoslof; no further 

volcanism has been reported (Byers, 1959).

The most recent activity occurred in July 1992 when 

steam and ash plumes were reported rising up to 8 km 

above the main island (Smithsonian Institution, 1992). 

U.S. Coast Guard observations and photography on July 

24 confirmed that a new 100-m-high lava dome had been

continued

55
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

constructed on the north tip of the island adjacent to the 

remnant 1927 lava dome. Harbin (1994) reports this dome 

to be about 150 m high, 150 m x 275 m in diameter, and 

composed of hornblende basaltic andesite. Eruptive 

activity had subsided by late July, 1992; several active 

fumaroles with temperatures as high as 165° were found on 

the dome in 1994 (Harbin, 1994).

Composition

Considerable detailed petrographic information is 

available for many phases of Bogoslof's eruptive history. 

Vent agglomerate of the 1796 eruption contains abundant 

angular fragments of limonite-stained hornblende-bearing 

andesitic porphyry (figs. 65, 66) in a grayish matrix of ash 

(Byers, 1959). The porphyry fragments resemble the 

eroded remnant of the 1796 lava dome of Castle Rock 

(Byers, 1959; Arculus and others, 1977).

The 1883 Fire Island dome is composed of nephelinenormative hornblende basalt (Arculus and others, 1977). 

Ash that fell at Unalaska village during the 1883 eruption 

has a slightly higher silica content than that of the lava 

flows (Byers, 1959).

Basaltic ash and agglomerate produced in 1926 

comprise almost 3 m of section at the north end of 

Bogoslof Island. A sample examined by Arculus and others 

(1977) contains about 10% hornblende phenocrysts, zoned 

plagioclase (bytownite to andesine), calcic augite, and 

scattered xenoliths of hornblende gabbro. Lava samples 

from fragments in the agglomerate and from the 1927 

dome consists of hornblende phenocrysts and inconspicuous phenocrysts of plagioclase and clinopyroxene; the 

groundmass of both rock types is microlitic plagioclase, 

clinopyroxene, opaque oxides and glass (Byers, 1959). The 

dome lava differs from the tephra in that it has more 

altered amphiboles and additional groundmass phase of 

anorthoclase(?). As pointed out by Byers (1961), Bogoslof 

lava flows erupted from 1796 to 1927 are progressively 

less siliceous.

No petrographic information is available for the 

constituents of Ship Rock, Metcalf Cone, McCulloch Peak 

or Tahoma Peak.

Bogoslof lava flows are more alkalic and more SiO2- 

undersaturated than lava flows on adjacent Umnak Island 

(Byers, 1961, p. 104-105). Amphibole-bearing basalts are 

rare in island arcs, and the absence of olivine and abundance of amphibole in basalts is unusual (Arculus and 

others, 1977). Based mainly on isotopic ratios, Arculus and 

others (1977) suggest that the Bogoslof eruptions of 1796 

and 1926-27, though separated by geologically very short 

time intervals, were associated with genetically separate 

magmas and are not directly related by simple fractional 

crystallization.

50 55 60 65 70 

SiO2 WT.%

75 80

Figure 65. Total alkalies-silica diagram of Bogoslof 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of 165°W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

1

Q

O 5

o>

P 4

S

U. 3

2

1

45 50 55 60

SiO, WT.%

65 70 75

Figure 66. FeO/MgO-silica diagram of Bogoslof volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of oceanic affinity (those located west of 

165°W longitude). Tholeiitic versus calc-alkaline 

discriminant line from Miyashiro (1974).

56
- CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME: OKMOK VOLCANO

SYNONYMS: 

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

OKMOK CALDERA

CENTRAL SHIELD COMPLEX WITH NESTED

CALDERA

UMNAK ISLAND, IN THE EASTERN ALEUTIAN

ISLANDS ABOUT 340 KM WEST-SOUTHWEST OF

THE TIP OF THE ALASKA PENINSULA

53°24'N, 168°10'W

1073 M

UMNAK

1102-29

Form and structure

Okmok Volcano occupies most of 

northeastern Umnak Island (fig. 67). 

The volcano, built on a base of 

Tertiary volcanic rocks, consists of 

three rock series: older flows and 

pyroclastic beds of a pre-caldera 

shield complex; pyroclastic deposits 

of two major caldera-forming 

eruptions; and a post-caldera field of 

small cones and lava flows that 

includes historically active vents 

within the caldera (Byers, 1959).

Construction of the pre-caldera 

volcano began in late Tertiary or early 

Quaternary time. Two whole-rock KAr analyses of a sample of basaltic 

lava are 1.7 ± .2 and 2.1 ± .2 m.y. 

(Bingham and Stone, 1973). Basaltic 

flows and pyroclastics compose most 

of the older rocks (unit Qbm, fig. 67); 

flows are more voluminous than 

pyroclastic deposits (see Byers, 1959, 

plate 41). Vent agglomerate is 

exposed in the walls of the younger 

caldera and tuffs and tuff-breccias 

occur further down the flanks. Flows 

and pyroclastic beds dip radially from 

the caldera at less than 5° in most 

sectors, except for local steepening 

and reversal of dips at former vents. 

Such radial dips suggest that the older 

complex was a central volcano with 

parasitic vents. Domes and plugs of 

andesitic and rhyolitic composition and basaltic lava flows 

(Byers, 1959, p. 312) mark minor vents that were active

168° 15' 168 00' 167 45'

- 53° 30'

53 20'

Contour Intervals 500 feet

1958 lava flows

Surficial deposits

After Byers, 1959

QUATERNARY

QUATERNARY - 

TERTIARY

Volcanic rocks of post-caldera age; includes lava 

flows and cones both within and outside Okmok caldera

Okmok volcanics; pyroclastic deposits 

of 2 caldera-forming eruptions

Volcanic rocks of 

pre-caldera age

Hydrothermally altered 

volcanic rocks

Site of 1945, 1958 eruptions 

Caldera

Index Map

of 

Umnak Island

Figure 67. Generalized geologic map of Okmok caldera 

and vicinity after Byers (1959).

57
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

before caldera formation; these rocks are only slightly 

modified by erosion and are presumably early post-glacial 

in age.

Catastrophic pyroclastic eruptions resulted in the 

formation of 2 overlapping calderas (Byers, 1959, p. 274). 

The deposits, referred to as the Okmok Volcanics (Byers, 

1959, p. 314), are mainly thick, non-sorted agglomerate at 

the caldera rim overlain by ash-flow tuffs, and airfall ash 

and pumice that cover the flanks of the volcano to the 

shoreline (unit Qov, fig. 58). Two arcuate ridges located 

about 1.5 km north and east of the main topographic basin 

are the remnants of the older caldera, which formed about 

8200 years ago (Black, 1975). The topographic basin of 

the younger caldera is about 9.5 km in diameter; the 

maximum elevation of the rim is about 1070 m and the 

mean elevation of the floor, exclusive of areas underlain 

by post-caldera volcanic rocks, is about 370 m. The 

occurrence of 2 major ash-flow sheets, separated by a 

basalt flow and an erosional unconformity, supports the 

two caldera-forming eruptions (Miller and Smith, 1975). 

Miller and Smith (1987) have reported a maximum 14C age 

of 2400 ± 200 yr for the second and younger calderaforming eruption.

Numerous small flows, plugs, and cinder cones on the 

flanks of Okmok Volcano are interbedded with or overlie 

the upper parts of the Okmok Volcanics (unit Qyv, fig. 58). 

Within the caldera, the oldest post-caldera deposits are 

brecciated pillow lavas and pyroclastic rocks that were 

deposited in a caldera lake. The lake attained a maximum 

depth of about 150 m and the upper surface reached an 

elevation of about 475 m, at which point it overtopped the 

low point of the caldera rim. A small shallow lake located 

near the outlet of the caldera is all that remains today. 

Three dissected tuff cones may have been produced by 

eruptions beneath the former caldera lake. Other cinder 

cones occur atop pillow lavas; such cones apparently 

breached the surface of the former lake. Cinder cones and 

associated lava flows that are younger than the caldera 

lake are identified by structures and textures characteristic 

of subaerial eruption. The documented eruption of 1945 

occurred at a cinder cone near the southwest caldera wall 

(Byers, 1959; Robinson, 1948); this cone may have been 

the site of all historical activity of Okmok volcano. Hot 

springs and fumaroles occur both within Okmok caldera 

and at Hot Springs Cove, 20 km to the southwest.

Volcanic activity

1805

Mar 1, 1817

1824-30

1878

1899

March 21-May 13,1931

1936

1938

June 1943 

June-Dec., 1945 

Aug., 1958 

Oct., 1960 

March 24, 1981 

July 8, 1983 

Nov. 1986-Feb. 1988 

Feb. 11, 1997-April 1, 1997

Several major eruptions and a number of minor events 

have occurred in Okmok caldera in historic time. Many of 

these episodes were originally ascribed to Tulik Volcano, 

3 km southeast of Okmok but this deeply glaciated peak 

almost certainly has not erupted in the last 200 years 

(Coats, 1950). Early records of eruptive activity at Okmok 

are sketchy. Several vents on the caldera floor have 

probably been involved. Major explosive eruptions 

occurred in 1817 and 1899 (Coats, 1950); the former 

deposited large quantities of coarse ejecta to the north 

along Cape Tanak and buried the Aleut village situated 

there (see Dall, 1870). Petroff (1884, citing Grewingk, 

1850) refers to a "flow of ashes" during the 1817 eruption. 

Formation of a new crater accompanied by earthquakes 

and a tsunami reportedly occurred in 1878 (Hantke, 1951). 

Less violent activity over the past 200 years probably 

produced lava flows (Byers, 1959) such as during eruptions in the 1820's, 1931, 1938, and 1945.

The course of the 1945 eruption is well documented 

(Robinson, 1948; Wilcox, 1959). On June 1, a sharp 

earthquake was felt at Fort Glenn army base, 16 km east of 

Okmok. The caldera itself was hidden by persistent low 

clouds until June 4, when pilots reported black ash rising 

to 3000 m near the southern rim. Observations on June 10 

revealed ash and lava bombs up to 1 m long being ejected 

from a small cinder cone near the southwest edge of the 

caldera floor. A lava tongue 12m thick issued from the 

cone's base at a rate of 0.15 m/s. This flow followed a 

circular path, undermining a large ice mass in the southern 

part of the caldera; it eventually extended about 6.5 km 

during a month of intermittent activity. Air-borne ash was 

carried southeast and deposited on the ice of the caldera 

floor to a depth of 1 m; several centimeters of ash collected on and immediately outside the caldera rim, and 

light traces were observed as far as 14.5 km from the 

active vent.

By late July, lava effusion had ceased and the eruption 

column was comprised principally of steam containing 

only minor amounts of ash. A brief resurgence of activity 

in December produced light ash fall and a small lava flow 

northeast of the cone; temperatures up to 1100°C were 

measured in this flow soon after its eruption. Although 

plans were made to evacuate Fort Glenn in early June, 

such action proved unnecessary. Ash fall at the military 

base was negligible and caused no significant damage to 

machinery or facilities; lava was confined within the 

caldera. The cone increased 30 m in height and developed 

a broad central crater during the 1945 event.

Eruptions including lava fountaining were reported in 

1958 and 1960 (Anchorage Daily News, August 16 and 19, 

1958; Anchorage Times, August 15, 1958; October 17, 

1960).

58
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

A commercial pilot observed an eruption on March 

24, 1981 from the cone of the 1945 eruption. The ash and 

steam plume rose to about 5500 m altitude and drifted to 

the northwest (Bulletin of Volcanic Eruptions, 1987).

On July 8, 1983 a small ash eruption was observed by 

a local pilot and on satellite imagery (Newhall and 

Dzurisin, 1988). A commercial pilot also reported a steam 

and ash plume above a cinder cone (probably the 1945 

cone) in the southwestern part of the caldera on November 

18, 1986. Another small ash eruption occurred from the 

same cone on January 5, 1987 about 13 hours after a 

shallow, magnitude 6.6 (Ms) earthquake struck 130 km 

south of Okmok. A small pyroclastic flow was produced 

on the southeast flank of the cone and ash emission from 

the cone continued intermittently from January 1987 to 

February 1988 (Smithsonian Institution, 1983, 1986, 1987, 

1988).

The most recent eruption at Okmok began on or about 

February 11, 1997 when a steam and possible ash plume 

was reported by pilots. An eruption from Cone A (Byers, 

1959), located on the caldera floor near the south rim (fig. 

67) and last active in 1945, was verified by additional pilot 

reports and satellite imagery. By February 13, the intracaldera cone was in a state of moderate strombolian 

eruption with a dark ash plume rising from the caldera and 

a lava flow extending from the cone. The eruption produced lava fountains, multiple spatter-fed and effusive lava 

flows that nearly crossed the caldera floor. Frequent 

explosive events sent ash to 16,000 ft ASL and at least 

once to a reported 30,000 ft ASL during the first two 

months of the eruption. Satellite imagery and reports from 

pilots and ground observers indicate that the main phase of 

the eruption continued sporadically through early April 

although steam emissions and occasional minor ash bursts 

continued for several more months. The exact end of 

eruptive activity is uncertain because of the remote 

location and poor weather frequently obscuring visibility.

Composition

Flows of the pre-caldera volcano are mainly basalts; 

some smaller flows are more silicic (figs, 68, 69). The 

basalt is both aphyric and porphyritic. Phenocrysts include 

olivine, augite, and plagioclase, with or without opaque 

phases. Byers (1959; 1961) and Nye and Reid (1986) 

present analyses of pre-caldera basalts, with a range of 

SiO2 content from 46.3% to 52.3%. Rhyolite, in the form 

of alternating bands of dense black obsidian and light grey 

felsite, occurs as an inferred dome in a radial fracture near 

the 8200 yr caldera rim. The rhyolite is presumably 

younger than most pre-caldera basaltic rocks, and is 

covered by Okmok volcanics. The youngest pre-caldera 

rocks are a sequence of aphyric basaltic flows, exposed 

only in the north wall of the caldera, with a total exposed 

thickness of 150 m.

Four analyses of the Okmok volcanics range from 

54.4% to 65.5% SiO2 (Byers, 1959). Two samples from the 

lower, agglomeratic part of the Okmok volcanics are 

distinctly lower in silica content (54.4% and 57.4%) than 

are two samples from the upper, pyroclastic-rich portion 

(63.8% and 67.6%).

Post-caldera volcanic rocks within Okmok Caldera are 

mainly of basaltic composition.

50 55 60 65 70

SiO2 WT.%

75 80

Figure 68. Total alkalies-silica diagram of Okmok volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of oceanic affinity (those located west of 

165°W longitude). Discriminant lines and field names (Le 

Bas and others, 1986) are explained on Figure 2.

O 

en

': . %:?.. V

':.9^&.*£x? ^&**^-

45 50 55 60 65 

SiO, WT.%

70 75

Figure 69. FeO/MgO-silica diagram of Okmok volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of oceanic affinity (those located west of 

165°W longitude). Tholeiitic versus calc-alkaline 

discriminant line from Miyashiro (1974).

59
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME: VSEVIDOF VOLCANO

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

MOUNT VSEVIDOF

STRATOVOLCANO

UMNAK ISLAND, WESTERNMOST OF THE Fox

ISLAND GROUP N THE EASTERN ALEUTIAN

ISLANDS, ABOUT 388 KM WEST SOUTHWEST OF

THE TIP OF THE ALASKA PENINSULA

53°08'N, 168°41'W

2149 M

UMNAK

1101-27

Form and structure

Mount Vsevidof is a symmetrical stratovolcano near the southwest end of Umnak Island. 

It is about 10 km wide at the base (fig. 70) and 

steepens from 15° at 300 m altitude to about 30° 

near the summit. A circular crater, 1.2 km in 

diameter, occupies the summit. Glacial ice fills 

the crater and extends down the north and east 

flanks of the cone; some of these glacial 

tongues have incised narrow canyons up to 120 

m deep.

A chain of small cinder cones (unit Qc, 

fig. 70) below altitude 1220 m parallels a rift on 

the western flank (Byers, 1959). Young flows of 

andesite and dacite (unit Qvf, fig. 70) were 

extruded from this rift and from other vents on 

north and south flanks of the cone. Pyroclastic 

deposits, apparently products of a culminating 

summit eruption, attain a thickness of more than 

30 m at the crater but thin downslope.

The oldest Vsevidof flows (unit Qvba, 

fig.70) are overlain by till of the last major 

glaciation, but the bulk of the cone is believed 

to be of post-glacial, i.e., Holocene, age. The 

cone is locally underlain by hyperstheneandesite lava flows and pyroclastic rocks of the 

more deeply eroded Mount Recheshnoi. Lava 

flows from both Recheshnoi and Vsevidof 

unconformably overlie a basement of probable 

early to middle Tertiary age including plutonic 

rocks (unit Tdp, fig. 70) and altered sedimentary 

and metamorphic rocks.

Figure 70. Generalized geologic map of Mount 

Vsevidof volcano after Byers (1959).

sa'of

Contour Interval 1000 f««t After Byers, 1959

QUATERNARY

Surficial adeposits

Youngest lava

flows 

Pyroclastic

deposits 

Lava flows

Cinder cone 

deposits Volcanic rocks of 

Mount Recheshnoi

Volcanic rocks of Mount Vsevidof

Plutonic rocks

Index Hap

of 

 » Umnak Island

61
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Volcanic activity

1784

May 30, 1790

1817

1830

1878

1880

March 11-12, 1957?

Several episodes of minor volcanism have been 

attributed to Vsevidof during historical time (see Byers, 

1959; Coats, 1950, Becker, 1898). "Smoke" was reported 

above the cone in 1784, 1790, and 1880. Activity was 

noted on the southwest end of Umnak Island in 1830 

(Petroff, 1884, citing Grewingk, 1850). The uppermost 

pyroclastic beds may have formed during one of these 

early eruptions (Byers, 1959, p. 305). Recorded activity in 

1878 may have been from a radial fissure eruption on the 

west flank; this event may have produced the youngest 

dacite flow, which extends west-south west to Cape 

Kigushimkada (Byers, 1959). Another phreatic eruption, 

possibly from the west rift, occurred in March, 1957 

(Byers, 1959, p. 305, citing article in Anchorage Times of 

March 12, 1957). Earthquakes were felt throughout 

southeast Umnak, and residents of Nikolski, the island's 

main village 24 km southwest of Vsevidof, reportedly 

observed discharges of steam and volcanic ash. However, 

in a subsequent article (Anchorage Times, March 15, 

1957) a pilot reportedly observed no evidence of a 

volcanic eruption.

Composition

Mount Vesvidof rocks are thoeliitic in character and 

composed (figs. 71, 72) of an older sequence of basaltic 

and andesitic lava flows, an intermediate sequence of 

dacitic pumice and andesitic scoria, and a younger series 

of more silicic flows of which one may have been erupted 

during historical time (Byers, 1961, p. 97). The older flows 

contain scarce phenocrysts (total 2 to 3%) of zoned 

plagioclase, euhedral olivine and augite in a groundmass 

of subparallel plagioclase microlites (Byers, 1959, p. 306).

The younger more silicic flows contain up to 5% (by 

volume) more phenocrysts than the older lava flows 

(Byers, 1959). Phenocrysts consist of hypersthene augite 

and plagioclase and the groundmass tends to have more 

orthoclase than that of the older flows.

Two distinct pyroclastic beds of the intermediate 

series may have formed in a culminating summit eruption 

that occurred no more than several thousand years ago 

(Byers, 1959). The lowermost is a welded, greyish-orange 

dacitic pumice bed; the lower bed grades upwards into a 

layer of irregularly banded andesitic scoria with minor

clots of black andesitic glass. Both the pumice and scoria 

beds contain 10 to 15% accessory blocks of andesite and 

diorite.

45 50 55 60 65 70

SiO, WT.%

75

Figure 71. Total alkalies-silica diagram of Vsevidof 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of 165° W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

50 55 60 65 

Si02 WT.%

70 75

Figure 72. FeO/MgO-silica diagram of Vsevidof volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of oceanic affinity (those located west of 

165°W longitude). Tholeiitic versus calc-alkaline 

discriminant line from Miyashiro (1974).

62
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

KAGAMIL VOLCANO

KAGAMIL ISLAND

STRATOVOLCANO

KAGAMIL ISLAND, NORTHEASTERNMOST OF THE

ISLANDS OF THE FOUR MOUNTAINS GROUP;

467 KM WEST-SOUTHWEST OF THE TIP OF THE

ALASKA PENINSULA

52°58'N, 169°43'W

893 M

SAMALGA ISLAND

1101-26

Form and structure

Kagamil volcano 

occupies most of the southern 

half of Kagamil Island, 55 km 

west of Umnak Island in the 

eastern Aleutian arc. The 

volcano consists of two cones 

and has an oval shape, 3.5 by 

2 km in basal dimensions, 

with the long axis trending 

northwest-southeast (fig. 73). 

The larger cone at the 

southeastern end of the 

volcano has an elevation of 

893 m; the cone at the 

northwestern end is about 

610m high and appears to 

have two small summit 

craters. Hot springs and 

fumaroles occur near the 

southeastern shore of the 

island (Sekora, 1973).

169° 45' 

I

169° 40' 

I

2 mi

2 km

Kagamil Pass

52° 59'

52° 58'

52° 57'

Contour interval 200 feet

Figure 73. Topographic map of Kagamil volcano.

Topography modified from 

U.S. Geological Survey 

Samalga Island Quadrangle 

map (1 : 250,000 scale)

Both cones appear to be virtually undissected by 

erosion, indicating a post-glacial age. The cones rise from 

a more gently sloping surface with mean elevation of 

about 200 m.

Volcanic activity 

December, 1929

Historical reports of volcanism of the island are 

meager. Veniaminov (1840) stated that Kagamil "formerly" flamed and smoked and solfataric activity was 

reported in the 1800's on Kagamil Island (Waring, 1965).

Coats (1950) mentioned only a single period of activity 

in December, 1929 but gives little information on the 

eruptive pattern or products of this event. Murie (1959) 

noted that "noisy steam jets issued from a rocky bluff and 

rumblings could be heard under the boulder beach" during 

a biological reconnaissance of Kagamil conducted in 1937.

Composition

No information is available concerning the composition of Kagamil Volcano. Presumably it consists of 

intercalated lava flows and pyroclastics of basaltic and/or 

andesitic composition like other cones in the eastern 

Aleutian arc.

63
 CATALOG or THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

CLEVELAND VOLCANO

MT. CLEVELAND

STRATOVOLCANO

CHUGINADAK ISLAND, EAST CENTRAL PART OF

ALEUTIAN ARC IN THE ISLANDS OF THE FOUR

MOUNTAINS, 490 KM WEST OF THE TIP OF THE

ALASKAN PENINSULA.

52o49'N, !69o57'W

1730 M

SAMALGA ISLAND

1101-24

Form and structure

Mt. Cleveland is a stratovolcano that comprises the entire 

western half of Chuginadak Island, 

40 km west of Umnak (fig. 74). 

Distinctively conical and symmetrical in form, Cleveland is 

about 8.5 km in diameter and is 

joined to the rugged, though lower, 

eastern half of the island by a low, 

narrow strip of land (fig. 74). 

Sekora (1973, p. 36) reports that 

this strip is dotted with "lava flow, 

cinder and ash patches, and 

conical hills."

Although it is the tallest 

member of the Four Mountains 

group, Mt. Cleveland is reported to 

lose snow more rapidly than 

neighboring peaks presumably 

from anomalous heat generation 

(Sekora, 1973, p. 27). Hot springs 

were noted at the base of a volcano 

on Chuginagak Island in the 

1800's (Waring, 1965).

Like many other Aleutian

volcanoes, the lower flanks of Mt. Cleveland up to about 

the 300 m elevation are more irregular and dissected than 

the upper flanks. The cones on the eastern half of 

Chuginadak Island are dissected by broad valleys presumably eroded in part by glaciers; in contrast, the upper cone 

of Mt. Cleveland is virtually undissected.

0 2 4 km Concord Pt 

i i i

PACIFIC OCEAN

- 52° 55'

- 52° 45

Contour interval 1000 feet Topography modified from 

U.S. Geological Survey 

Amukta (1:250,000 scale) 

Samalga Island (1:250,000 

scale) Quadrangle maps

Figure 74. Topographic map ofMt. Cleveland and other 

volcanoes of the Islands of the Four Mountains.

65
 CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Volcanic activity

1893

1897

1929(?)

Jan., 1932

1938

June 10-12, 1944

Nov.-Dec., 1951(?)

1975(?)

April 28 - July, 1986

June - August, 1987

May 25, 1994

The Islands of the Four Mountains area are remote 

and uninhabited; consequently, information exists on only 

three 1932, 1944, and 1953 of the eight reported 

episodes of eruptive activity before 1982 (Coats, 1950; 

Powers, 1958; Simkin and others, 1981; Smithsonian 

Institution, 1986, no. 12). It is possible that several late 

18th and 19th century eruptions attributed to Carlisle 

Volcano should in fact be ascribed to Cleveland (Coats, 

1950).

The 1932 eruption, which began in January and 

proceeded for an indeterminate length of time, was 

explosive in nature.

The 1944 eruption was characterized by two days of 

Vulcanian explosive activity from the central crater, which 

produced lava flows as well as tephra (Simkin and others, 

1981). Severe earthquakes were felt throughout the 

episode. Clouds of steam and ash rose to 6000 m and lava 

flows extended 5 km from the central crater. Boulders "as 

big as automobiles" were ejected across the island and for 

a considerable distance into the surrounding ocean 

(Alaskan Sportsman, 1944; Freiday, 1945). This eruption 

of Mt. Cleveland has the infamous distinction of having 

resulted in the only reported historical fatality attributable 

to volcanic activity in Alaska. A small detachment of the 

Eleventh Army Air Force was stationed on Chuginadak 

Island and one soldier who apparently advanced too close 

to the active vent during a reconnaissance investigation 

was killed (Smithsonian Institution, 1985); the soldier was 

possibly killed by a mudslide (Lowney, 1946). Army 

personnel and equipment were evacuated from the island 

and the outpost was abandoned for the duration of the war 

(Anchorage Daily Times, June 26, 1944; Robinson, 1948).

On June 25, 1953, a military observer reported dark 

ash on the snow around the vent of Mt. Cleveland (report 

on file at Geophysical Institution, University of Alaska, 

Fairbanks).

An increase in commercial air and sea traffic subsequent to 1980 has resulted in more frequent reports of 

activity on Mt. Cleveland. Fairly continuous fumarolic

activity has occurred since 1982 (Smithsonian Institution, 

1985). In May through July of 1986 minor ash, steam, and 

incandescent zones in the summit crater were reported 

(Smithsonian Institution, 1986, nos. 4, 6).

Activity during June - August of 1987 included ash 

and steam emission, minor lava flows, and a short interval 

of active lava fountaining from the summit crater vent; an 

incandescent feature was observed in the summit crater. 

On August 28, 1987, a large eruption of Mt. Cleveland was 

recorded by remote sensing and satellite imagery. A 

sustained rumbling was audible to a ground party on 

Kagamil Island, 25 km to the northeast, however, overcast 

conditions prevented direct observation. An approximate 

10-km-high plume, elongated in a west-northwest direction, was recognized on satellite images (Smithsonian 

Institution, no. 6, 1987; no. 7, 1987; no. 8, 1987). Pilot 

reports received by the Alaska Volcano Observatory 

indicate that on May 25, 1994, an explosive event sent a 

short-lived ash plume to -10.5 km altitude.

Composition

No information is available.

66
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

Form and structure

Carlisle Island consists of a single symmetric cone, 

1524 m high and 6.5 km in diameter at sea level (fig. 74); 

its steep upper slopes are generally snow-covered year 

round. Little is known about Carlisle volcano's structure 

and composition. The topography suggests that the lower 

slopes of Carlisle are slightly more irregular in form and 

more dissected by erosion than are the uppermost slopes. 

According to Sekora (1973), the western margin of the 

island consists of a small plateau at an elevation of 50 m, 

suggesting that the Carlisle stratovolcano is constructed on 

an emergent marine terrace.

Volcanic activity

1774 

1828 

1838 

Nov. 1987

Carlisle was reported "active" in 1774 and 1828, and 

"smoke" was noted above the island in 1838 (Coats, 

1950). However, documentation of these episodes is poor. 

Various names were applied to Carlisle on early hydrographic charts, including Uliaga, Kigalgain and variants 

thereof; it was also sometimes referred to along with the 

western half of Chuginadak Island, as Tanak-Angunak. It 

is thus possible that some of the activity ascribed to 

Carlisle should be attributed to Uliaga or Mount Cleveland 

(Coats, 1950). Petroff (1884, citing Grewingk, 1850) lists 

activity at "Chegulakh" (53° 08'N, 169° 24'W) and 

"Ouliagan" (52°53'N, 169°40'W) for the period 1700- 

1710. Coordinates for "Chegulakh" plot near modern 

Kagamil volcano, whereas "Ouliagan" could actually be 

Carlisle Volcano or Mount Cleveland. A separate listing is 

given for "Taunakh-Angunakh", which is either Mount 

Cleveland on Chuginadak Island or Carlisle Volcano. 

However, a separate listing is also given for Kagamil and 

there is some question as to whether "Chegulakh" actually

CARLISLE VOLCANO

CARLISLE ISLAND

STRATOVOLCANO

CARLISLE ISLAND, IN THE ISLANDS OF THE

FOUR MOUNTAINS GROUP; ABOUT 491 KM

WEST-SOUTHWEST OF THE TIP OF THE ALASKA

PENINSULA

52°54'N, 170°03'W

1620 M

AMUKTA

1101-23

refers to Kagamil. Furthermore, other entries for activity in 

"the Four Peaks islands" are given for 1796-1800. Any of 

the activity during 1700-1710, 1774, 1796-1800, 1828, and 

1838 could refer to Carlisle Volcano as well as to Mount 

Cleveland or even Kagamil Volcano.

The most recent activity occurred during mid to late 

1987. Steam was reported emerging from the summit of 

Carlisle on August 28, and on November 16, two pilots 

observed a plume of steam and some ash rising to 2500 m 

altitude and streaming 30 km east-northeast from the 

summit of a volcano they tentatively identified as Carlisle; 

however, the eruption could possibly have been from Mt. 

Cleveland, 10 km to the southeast, which had also recently 

been active (Smithsonian Institution, 1987.

Composition

Carlisle Island has not been mapped. The volcano is 

assumed to consist of interbedded basaltic and/or andesitic 

lava flows and pyroclastics.

67
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

YUNASKA VOLCANIC COMPLEX

YUNASKA ISLAND

SHIELD VOLCANO WITH CALDERA AND

ASSOCIATED STRATOVOLCANOES, CINDER CONES

AND LAVA FIELD

YUNASKA ISLAND, IN THE ISLANDS OF THE

FOUR MOUNTAINS GROUP; ABOUT 540 KM

WEST-SOUTHWEST OF THE TIP OF THE ALASKA

PENINSULA

52°38'N, 170°38JW

550 M

AMUKTA

1101-21

170° 50' Form and structure

Yunaska Island lies near the 

west end of the Islands of the Four 

Mountains group and is flanked by 

Chagulak and Amukta Islands on the 

west and the remainder of the group 

on the east. Yunaska Island is 

roughly oval in form and about 

23 km long. It consists of two 

volcanic centers separated by a flat 

valley with moderately sloping walls 

(fig.75). The western volcano, 950 m 

high, is the eroded remnant of a 

series of four overlapping 

stratocones (Nicolaysen and others, 

1992); a group of cinder cones and 

fissure flows extends from the west 

end of the stratocone complex. This 

western volcano has presumably not 

been active in historical time.

The eastern volcanic center, to 

which all recent Yunaska volcanism 

has been attributed, has been 

described by Nicolaysen and others 

(1992) and Lamb and others (1992) in preliminary reports 

as a large shield volcano topped by two overlapping 

calderas. No age has been reported for caldera formation 

but the fresh morphology of the younger caldera and the 

non-glaciated nature of the associated pyroclastic rocks 

suggests it at least is Holocene in age. The older of the two 

calderas (caldera CI, Lamb and others, 1992) has a 

diameter of 10-13 km, the younger (caldera CII) about 

3 km. Low ridges and peaks along the northern and eastern 

shores of the island define the postulated caldera (see

170° 40'

-52° 40'

-52° 35'

Contour Interval 500 feet Topography modified from 

U.S. Geological Survey 

Amukta (1:250,000 scale) 

Quadrangle map

Figure 75. Topographic map of Yunaska volcano.

physiographic descriptions in Sekora, 1973). Sinuous 

ridges and small cones, craters, and lava flows of the 

active field occur both within and outside caldera II. The 

most prominent flow extends 1.5 km south from the 

southwestern lip of caldera II but does not reach the sea. A 

second area of relatively young lava flows lies north of the 

caldera, and a smaller flow is situated on the east flank.

69
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Known cones and inferred lava vents outside the caldera 

are located within 1 km of the rim. Within the caldera is a 

500 m cone that has its own small summit crater. Low 

relief on the eastern part of Yunaska Island implies that 

either the pre-caldera volcano had a shield-like form, or 

that a former cone has been subsequently destroyed. No 

hot springs or active fumaroles are known to exist on the 

island.

Volcanic activity

1817 1929?

1824 Nov. 3-4, 1937

1830

Several episodes of minor volcanism and two violent 

events have been attributed to Yunaska Island in historical 

times. Smoke was reported in 1817 and possibly in 1929 

(Powers, 1958), and a minor ash emission was observed in 

1830. A major explosive eruption took place in 1824 (see 

Coats, 1950). The ship Boxer reported a "violent volcanic 

eruption" with "flames" originating from near the center of 

the island in early November of 1937 (Anchorage Times, 

November 4, 1937).

Composition

Like other members of the Four Mountains group, 

Yunaska Island has not been geologically mapped. 

Nicolaysen and others (1994) report in an abstract that the 

pre-caldera rocks include plagioclase + olivine basalt and 

andesite flows ranging in composition from 51-55% SiOr 

Cross-cutting dikes and post-caldera rocks include 

andesite to dacite compositions (56.4-64.5% SiO2).

70
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

AMUKTA VOLCANO 

AMUKTA ISLAND 

STRATOVOLCANO

AMUKTA ISLAND, WESTERNMOST OF THE ISLANDS OF THE FOUR MOUNTAINS GROUP; 

ABOUT 585 KM WEST-SOUTHWEST OF THE TIP 

OF THE ALASKA PENINSULA 

52°30'N, 171°15'W 

1066 M 

AMUKTA 

1101-19

Form and structure

The undissected stratovolcano of Amukta 

volcano composes most of nearly circular, 

7.7-km-wide Amukta Island (fig. 76). The 

cone, about 5.8 km in basal diameter and 

topped by a 0.4 km wide summit crater, 

appears on synthetic-aperature radar imagery 

to be built upon a 300+ meter high, east-west 

trending arcuate ridge. Extensions of that 

ridge on the southwest and east sides of the 

island indicate an older caldera approximately 

6 km in diameter and open to the sea on the 

south side. No hot springs or fumaroles have 

been reported from Amukta. Sekora (1973, 

p. 29) reports the presence of a cinder cone 

near the northeastern shore of the island.

171° 18' 171° U 1

Volcanic activity

1770? 

1786-1791 

1876 

February, 1963

July 12, 1984 

Aug., Sept. 1987 

July, Sept. 1996

Well documented reports of historical 

Amukta volcanism are sparse; activity was 

noted from 1786 to 1791, and again in 1876 

(Coats, 1950). Petroff (1884, citing 

Grewingk, 1850) lists activity at Amukhton in 

1770, presumably the same volcano; conversely, Dall 

(1870, citing Grewingk, 1850) describes a cessation of 

activity at Amukta in 1770.

On February 13, 1963 an eruption occurred involving 

the central crater and one or more parasitic vents; both ash 

and lava were produced (Anchorage Times, February 11, 

1963; Decker, 1967). Persistent low clouds obscured the

52° 30'

52° 28^

Contour interval 500 foot Topography modified from 

U.S. Geological Survey 

Amukta Quadrangle map 

(1 : 250,000 scale)

Figure 76. Topographic map of Amukta volcano.

exact source of the lava, but the flow was seen to extend 

from the west side of the cone southwest into the sea at 

Traders Cove (Bulletin of Volcanic Eruptions, 1963).

71
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

In early July 1996, a passing ship reported a 1-km 

high plume of "ash and smoke" (Neal and McGimsey, 

1997). On August 28 Mt. Cleveland, 100 km to the 

northeast, was also active and winds were blowing towards 

Amukta. In late August and early September, 1987, a 

commercial pilot observed a 10.5-kilometer-high eruption 

plume rising through cloud cover near Amukta Island. On 

September 4, another pilot observed a small dark ash 

plume issuing from the summit of Amukta (Smithsonian 

Institution, 1987). On Sept. 18, yet another pilot reported a 

300m-high ash plume.

Composition

No geologic map or rock descriptions are available for 

Amukta volcano.

72
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

SEGUAM VOLCANO

PYRE PEAK

STRATOVOLCANO WITHIN CALDERA(?)

SEGUAM ISLAND is IN THE CENTRAL ALEUTIAN

ARC, 645 KM WEST-SOUTHWEST OF THE TIP OF

THE ALASKAN PENINSULA

52°19'N, 172°31rW

1054 M

SEGUAM

1101-18

Form and structure

Seguam Island consists of the 

remnants of two late Quaternary calderas. 

Holocene volcanic cones occur in both of 

the calderas and a third Holocene cone 

lies at the east end of the island. Pyre 

Peak, commonly referred to as Sequam 

volcano (fig. 77), highest of the young 

cones, dominates the western half of the 

island and occupies the center of the 

western caldera (Singer and others, 1992) 

that is defined by remnants of a semicircular ridge about 3 km in original 

diameter and about 700 m high. A 

Holocene basalt field surrounds Pyre 

Peak (Singer and others, 1992) extending 

down to shoreline. This general area has 

been the site of most if not all historical 

volcanic activity. Late Quaternary lavas 

and pyroclastic rocks ranging in age from 

1.1 Ma to 0.03 Ma underlie the basalt. 

The two Holocene cones to the east are 

surrounded by andesite and dacite lava 

flows with well preserved constructional 

features (Singer and others, 1992).

Volcanic activity

1786-1790 

1827

December 1891 

Spring, 1892

Seguam Island

Countour Interval 500 feel Adapted from Myers and Singer (1987) and 

J.D. Myers, unpublished data, 1989

QUATERNARY

QUATERNARY - 

TERTIARY

1901?

1927

March 6, 1977

December 27, 1992

July 31-August 19, 1993

Several episodes of volcanism have been attributed to 

Seguam Island in the past 200 years, and it is likely that 

other events have gone unrecorded due to the remoteness

Oal^ Glacial and lake sediment 

 I

*QbJ*l Cheifly basalt flows

S.QujySJ Undifferentiated flows and domes

QTu- 1 Undifferentiated flows and pyroclastic deposits

^ f

A Caldera margin

Figure 77. Geologic map of Sequam Island modified from 

Myers and Singer (1987) and J.D. Myers, unpublished 

data, 1989.

and inclement weather of the region. The earliest documented activity is 1786-90 (Grewingk, 1850, cited in 

Petroff, 1884). "Smoke" was reported in 1827, and in

73
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

December of 1891 a minor eruption was reported (Coats, 

1950). The most vigorous of the early eruptions took place 

in the spring of 1892; it produced detonations heard at the 

village of Atka, 120 km to the west, and two large cauliflower-shaped jets of ash (Jaggar, 1927; Coats, 1950).

In early March, 1977 the crew of the U.S. Coast 

Guard Cutter Mellon reported eruptive activity. Eight lava 

fountains, up to 90 m high, were noted along a radial rift 

about 1 km long and about 2.5 km southwest of the 

summit. At least two tongues of lava were extruded. The 

larger flow, 1 km wide, extended 2.5 km to the southwest; 

the smaller, 0.5 km wide, extended 1 km south. Neither 

tongue entered the sea. Pyroclastic material was also 

produced during the event. Dense clouds containing black 

ash and incandescent fragments were emitted from one or 

both of the vents effusing lava, and a coating of fine ash 

was visible on the surrounding snow. By March 8th, lava 

extrusion and fountaining had apparently ceased, but a 

considerable amount of steam, possibly containing some 

ash, was still being discharged. (Anchorage Times, March 

8, 1977; Smithsonian Institution, 1977).

In late December 1992, U.S. Coast Guard pilots 

reported an ash cloud up to 1200 m above Pyre Peak, the 

site of the 1977 eruptive activity. Intermittent, localized 

bursts of ash rising 100-200 m were observed several days 

later, and the activity apparently subsided soon after 

(Smithsonian Institution, 1992). Explosive ash eruptions 

along with a lava flow were reported by Coast Guard 

observers from July 31, 1993 through August 19, 1993; 

ash clouds were reported to altitudes of 3,500 m at times 

during this interval.

Composition

Holocene post-Pyre Peak caldera lava flows, which 

were erupted from the vents along the caldera wall and 

from the central intracaldera cone, are highly porphyritic 

basalt (figs. 78, 79) in contrast to intracaldera dacite and 

rhyodacite in the eastern caldera (Myers and Singer, 1987). 

These young lavas overlie a sequence of Plio-Pleistocene 

andesitic flows and pyroclastic deposits that comprise the 

bulk of Seguam Island.

50 55 60 65 70 75 80

SiCL WT.%

Figure 78. Total alkalies-silica diagram for Sequam 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of!65°W longitude). Discriminant lines and 

fieldnames (LeBas and others, 1986) are explained in 

Figure 2.

O 5

O)

P 4

O

Q) _

u_ 3

45 50 55 60

SiO2 WT.%

65 70 75

Figure 79. FeO*/MgO-silica diagram of Sequam volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of oceanic affinity (those located west of 

165 °W longitude). Tholeiic versus calc-alkaline 

discriminant line from Miyashiro (1974).

74
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE:

CAVW NUMBER:

KOROVIN VOLCANO

NONE

STRATOVOLCANO

ATKA ISLAND, IN THE CENTRAL ALEUTIAN ARC

ABOUT 760 KM WEST-SOUTHWEST OF THE TIP

OF THE ALASKA PENINSULA

52°23'N, 174°09'W

1533 M

ATKA

1101-16

174°30' 20' 10"

20'

15-

174*30'

Form and structure

The active volcanic front runs 

through northern Atka Island which has been 

geologically mapped on a reconnaissance 

scale by Marsh (1990) who described the 

overall structure of the volcanic center as that 

of a broad central shield upon which a large 

stratocone (Atka volcano) had been built. This 

cone was destroyed during caldera formation 

about 300,000 to 500,000 years ago. Korovin, 

neighboring Kliuchef, and probably Konia 

(fig. 80) are products of the latest stage of 

volcanic activity on the island, which began 

perhaps about 100,000 years ago based on the 

degree of dissection (B. Marsh, written 

commun., 1982).

Korovin volcano is a stratovolcano, 

1533 m high and almost 7 km in basal 

diameter, having two summit vents 0.6 km 

apart (fig. 80). The northwestern summit vent 

is a symmetric cone with a small crater. The southeastern 

summit vent is on the remnant of a cone with a steepwalled crater, about 1 km wide at the rim and at least 

several hundred meters deep. Intercalated lava flows and 

pyroclastic rocks comprise the upper part of the crater 

wall, but the bottom one hundred meters or so are nearly 

vertical and apparently consist entirely of lava flows. A 

turquoise green lake fills the lower part of the crater; the 

color suggests the occurrence of solfataric activity 

(Sekora, 1973).

The west side of Sarichef and east flank of Konia are 

extensively dissected; Konia has a relatively fresh cinder 

cone on its west flank. Sarichef is most likely a satellite

Figure 80. Generalized geologic map of the north end of

Atka island including Korovin andMt. Kliuchef volcanoes;

adapted from B.D. Marsh (unpublished data).

North Cape

Konia

Mt. Kliuchef

ATKA ISLAND

Atka Village

20' 10'

GENERALIZED GEOLOGY 

Adapted from B.D. Marsh (Unpublished data)

Korovin 

Sarichef 

Konia 

Kliuchef

Relative ages of 

younger volcanlcs 

largely unknown

LIE]

Big Pink dacite flow

Atka Volcanics 

Andesitic basalt flows

from Atka volcano 

Subsidiary vents and

associated flows 

Old Harbor Volcanics

->^->- Contact

-D-D-D- Dike, dashed where uncertain 

® Thermal spring 

© Fumaroles

<"\

t._J Caideras or crater rim

75
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

vent of the earlier Atka volcano as is Kliuchef which is 

located on the northern rim of the Atka caldera. Korovin 

and Kliuchef are virtually undissected and are thus 

apparently of post-glacial age. Hot springs and fumaroles 

occur on the south and west flanks of Mt. Kliuchef and 

near the head of a glacial valley 6 km southwest of 

Korovin Volcano (Motyka and others, 1993).

Volcanic activity

1812 (Kliuchef) ?

1829-30

1844

1907?

1951? May 23, 1986 

1953-54? March 18,1987 

1973 

1976?

Minor volcanic activity has characterized northern 

Atka Island during historical time (Coats, 1950). One 

episode of activity in 1812 has been attributed to 

Sarichef by Grewingk (1850), although it probably was 

associated with either Korovin or Kliuchef. Of the four 

vents on Mt. Kliuchef, the most northeasterly one appears 

to be the youngest and may be the source for the eruption 

of 1812 attributed to Sarichef (B. Marsh, written 

commum., 1982). Ball (1870, citing Grewingk, 1850) 

listed violent eruptions and earthquakes for the 1812 

activity. Other eruptions have possibly gone unreported 

due to the endemic poor visibility and sparse population of 

the region.

Korovin has produced "smoke" and localized ash fall 

several times in the last 200 years. In 1907 "dense clouds 

of vapor" enveloped the summit of Korovin (Eakle, 1908) 

and a light coat of "fresh volcanic cinder" was observed on 

snowfields near Mt. Kliuchef (Jaggar, 1927, p. 24). Powers 

(1958) reported smoke in 1951 and various times in 1953 

and 1954 (reports on file at Geophysical Institute, University of Alaska, Fairbanks). In 1973, Atka villagers in a boat 

near North Cape reported a 10 m wide lava flow extending 

half way down the northern flank of Korovin volcano from 

a fissure vent located near the northern summit (Reeder, 

1988). "Smoke" emission was observed in 1976 at 

Korovin from Atka village, located 20 km to the south 

(Arctic Environmental Information and Data Center, 

1978).

Steam emission was observed in early May, 1986, and 

on May 23rd a 600 m steam plume containing some ash 

reportedly occurred soon after a 7.7 magnitude earthquake 

struck about 100 km to the southwest (Smithsonian 

Institution, 1986).

The most recent eruptive activity at Korovin was 

observed on satellite imagery taken March 18, 1987. Three 

plumes, each 95 km long, were drifting east-northeast 

from the summit of Korovin and several vents 5-6 km to 

the south (Kliuchef). Later that day, a >3000-meter-high 

ash plume was observed drifting southward from the 

summit of Korovin (Smithsonian Institution, 1987).

Composition

Marsh (1990) reports that more than 90% of the lava 

flows on Atka Island are basalt, having an average silica 

content of about 50%. He also noted a slight tendency 

towards more silicic compositions in the very latest stages 

of activity for each volcano; Korovin and Kliuchef are 

composed mainly of basalt but have late dacite flows.

Phenocrysts in the basalts are plagioclase (Ango 90), 

olivine (Fo70), titanomagnetite (Usp45), and clinopyroxene 

in the more advanced stages of crystallization (B. Marsh, 

written commun., 1982). Orthopyroxene replaces olivine 

in the more silicic rocks and trace biotite was reported 

from the summit dacite dome of Kliuchef.

45

SiO. WT.%

Figure 81. Total alkalies-silica diagram for Korovin 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of 165°W longitude). Discriminant lines and 

fieldnames (LeBas and others, 1986) are explained in 

Figure 2.

O 5

CD

P 4

O

0)

U_ 3

45 50 55 60

SiCL WT.%

65 70 75

Figure 82. FeO*/MgO-silica diagram of Korovin volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of oceanic affinity (those located west of 

165 °W longitude). Tholeiic versus calc-alkaline 

discriminant line from Miyashiro (1974).

76
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

KASATOCHI VOLCANO

KASATOCHI ISLAND

STRATOVOLCANO

KASATOCHI ISLAND, IN THE CENTRAL ALEUTIAN

ARC, ABOUT 838 KM WEST- SOUTHWEST OF

THE TIP OF THE ALASKA PENINSULA

52°11'N, 175°30'W

314 M

ATKA

1101-13

Form and structure 175° 3r

Kasatochi Island, like Gareloi, 

Bogoslof and several other volcanoes in the western Aleutian arc, 

represents the emergent summit of 

a predominantly submarine 

volcano. The island consists of a 

single, undissected cone with a 

central lake-filled crater about 

0.75 km in diameter (fig. 83). A 

maximum height of 314 m is on the 

southern crater rim; elevation of the 

lake is less than about 60 m. Kay 

(1990) reports a lava dome on the 

northwest side of the cone at an 

elevation of -150 m.

Coats (1956) refered to 

Kasatochi as one of a group of 

little-known volcanoes that appear 

to be stratovolcanoes composed of 

basaltic and andesitic flows and 

pyroclastics. The mean slope of the 

southern flank (about 18°) is 

considerably less than the mean 

slope of the northern flank (about 

45°). This asymmetry of form may 

reflect a predominance of lava

flows low on the southern flanks, or, it may be due to a 

higher rate of erosion by wave action from the north. 

Bathymetry indicated that Kasatochi is at the northern end 

of a 15-km-long, 6-km-wide submarine ridge that is 

normal to the trend of the Andreanof Islands. Water depths 

along the ridge are less than 90 m; if Kasatochi is constructed entirely on the ridge, the total height of the 

volcanic pile is only a little more than 400 m.

17 5° 30' 17 5° 29'

BERING SEA

Kasatochi island

52°1T

52°10'

Contour Interval 200 feet Topography modified from 

U.S. Geological Survey 

Atka Quadrangle map 

(1 : 250,000 scale)

Figure 83. Topographic map of Kasatochi Island volcano.

Volcanic activity

1760?

1827

1828

The recorded history of eruptions at Kasatochi is 

sparse; the episodes listed above were originally attributed

77
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

to Koniuji, a small volcanic islet situated 25 km to the east. 

Koniuji, however, is "deeply eroded" and "does not appear 

to have been active in Recent time"; the relatively 

undissected Kasatochi appears a more likely source of 

historical volcanism (Coats, 1950, Table 2). Little detail is 

available concerning the historical events: the island was 

reported "rising" in 1760 (Grewingk, 1850, cited in 

Petroff, 1884) and "smoke" was noted in 1827 and 1828. 

In 1899, the crater lake disappeared for a brief period 

while steam rose from the crater; the lake eventually 

reappeared (Jaggar, 1927). No activity has been confirmed 

at Kasatochi in this century.

Composition

There are no geologic maps and little petrologic data 

available for Kasatochi Island. Kay (1990) states that the 

lava flows and scoria are olivine basalt and pyroclastic 

rocks and dome lavas are hornblende andesite and dacite.

r.v'. " 

50 55 60 65 70 75 80

SiCL WT.%

Figure 84. Total alkalies-silica diagram for Kasatoachi 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of!65°W longitude). Discriminant lines and 

fieldnames (LeBas and others, 1986) are explained in 

Figure 2.

8

7

6

O 5

D>

P 4

O 

LL 3

2

1

45 50 55 60 65

SiO2 WT.%

70 75

Figure 85. FeO*/MgO-silica diagram of Kasatochi 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of 165°W longitude). Tholeiic versus calcalkaline discriminant line from Miyashiro (1974).

78
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

GREAT SITKIN VOLCANO

GREAT SITKIN ISLAND

STRATOVOLCANO WITH CALDERA AND DOME

GREAT SITKIN ISLAND, CENTRAL ALEUTIANS,

ABOUT 965 KM WEST-SOUTHWEST OF THE TIP

OF THE ALASKA PENINSULA

52°05'N, 176°08'W

1740 M

ADAK

1101-12

Form and structure

Great Sitkin Volcano occupies most of 

the northern half of Great Sitkin Island, a 

member of the Andreanof Islands group in 

the central Aleutian Islands. The volcano is 

roughly oval-shaped, 8 by 11 km at the 

base, with the long axis trending east-west 

(fig. 86). It is a composite structure consisting of the remains of an older, decapitated 

volcano and a younger parasitic cone that 

collapsed forming a small caldera (0.8 by 

1.2 km) on the west flank (Simons and 

Mathewson, 1955). The highest point on the 

island is apparently a remnant of the former 

central volcano's eastern rim. Most of the 

constructional surface of the cone has been 

deeply eroded. A steep-sided, recently 

emplaced dome (unit Qgd, fig. 86) occupies 

the center of the caldera at an elevation of 

1220 m. The dome is 183 m high, 0.4 km 

wide, and 0.6 km long with a blocky, flat 

top. Five small plugs (unit Qa, fig. 86) are 

intruded into the northwest slope of the 

cone; three of the plugs are aligned in a 

northwest direction from the crater, and the 

remaining two are aligned north-northwest.

Rocks that comprise the main cone are 

named the Great Sitkin volcanics (unit Tgc, 

fig. 86), and consist of andesite and basalt 

lava flows interbedded with tuff beds 

(Simons and Mathewson, 1955). Lava flows 

predominate on the upper part of the cone, 

which has undergone extensive glacial 

erosion; construction of the cone may have 

begun in late Tertiary or early Quaternary 

time and was apparently completed before

Bugle Ft

Contour Interval 1000 feet

QUATERNARY

From Simon and Mathewson, 1955

Surficial deposits

Basalt plugs

Basalt flows on Sitkin Creek

Composite cone of Great Sitkin Volcano

Agglomerate

Finger Bay volcanic

Figure 86. Geologic map of Great Sitkin Island from 

Simon and Mathewson (1955).

79
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

the end of Pleistocene glaciation. Partial destruction of the 

cone's former peak was followed by a westward shift in 

eruptive activity. A parasitic cone was built and subsequently destroyed during caldera-forming eruptions of 

unknown age. Pumice, scoria, and rock fragments from 

this eruption blanket the island to depths of a few centimeters to more than 6 m. Overlying the pumice deposit on the 

northwest flank of the main cone is an ash deposit that was 

apparently erupted from a subsidiary vent located immediately northwest of the crater (Simons and Mathewson, 

1955). A glacially truncated, columnar jointed basalt flow 

occurs low on the south flank of the main cone near the 

head of Sitkin Creek (unit Tgs, fig. 86). This flow is the 

product of a flank eruption, the source of which is covered 

by pumice (Simons and Mathewson, 1955, p. 31).

Great Sitkin volcano is built upon the eroded remnants 

of a late Tertiary shield volcano, which forms most of the 

southern half of the island. The undeformed succession, 

termed the Sand Bay volcanics by Simon and Mathewson 

(1955), consists of pyroclastic rocks, mainly volcanic 

breccias, which are overlain by a sequence of andesite and 

basalt lava flows. The succession crops out in a gently 

dipping radial pattern suggesting a source near the present 

cone.

The Sand Bay volcanics unconformably overlie the 

Finger Bay volcanics, an older, highly altered and deformed sequence of lava flows, breccia, and tuff that form 

the rugged headlands along the southern and southeastern 

coasts. By correlation with nearby Adak Island, the Finger 

Bay volcanics are probably no younger than late Eocene in 

age, and may be as old as Cretaceous (Scholl and others, 

1970).

Volcanic activity

1792 

1828-29 

1904 

Nov., 1933

March, 1945 

Aug. 14, 1946 

1949-50 ? 

19 Feb-Sept., 1974

Several episodes of volcanic activity, most relatively 

minor, have been reported for Great Sitkin Volcano since 

its discovery in 1741 during the Bering Expedition. Other 

eruptions have probably gone undetected as a consequence 

of the island's remoteness from principal shipping lanes. 

The major event that produced both the crater and the 

extensive pumice fall blanketing the island is interpreted 

by Simons and Mathewson (1955, p. 32,40) to have taken 

place within the past several thousand years, and possibly 

only a few hundred years ago.

In historical times, "smoke" has been reported above 

Great Sitkin in 1828-29, 1904, 1946, and 1951 (Simons 

and Mathewson, 1955; Wentworth, 1951, p. 6) and 

explosive eruptions in 1792, 1933, 1949-50, and 1974

(Anchorage Times, February 21, 1974; the 1974 event may 

have included some additional dome growth as well as 

vigorous phreatomagmatic activity. The ash layer on the 

northwestern slope of the main cone was probably 

deposited during one of these eruptions as it appeared to 

Simons and Mathewson (1955) as "at most only a few 

hundred years old". The most notable recorded activity 

occurred in March of 1945 when much of the crater dome 

was apparently extruded (Coats, 1950). A nocturnal glow 

was visible above Great Sitkin from Adak Island for a 

period of several weeks. Army aviators observed clouds of 

steam rising from the crater, and a strong earthquake was 

felt at Sand Bay during this time. Steam has been observed 

subsequent to dome emplacement, and on August 14, 

1946, a small smoke cloud was observed from Adak Island 

(Simons and Mathewson, 1955). Powers (1958) reports 

ash eruptions in 1949-50.

Activity at Great Sitkin during 1946-48 comprised 

periodic steam emission from the crater and the continued 

existence of a group of hot springs, mud pots and fumaroles about 4 km south of the crater rim (Byers and 

Brannock, 1949). The hot springs occur at the site of a 

possible volcanic vent that predates the rocks of Great 

Sitkin Volcano.

Composition

Petrographic information for rocks of Great Sitkin 

volcano is from Simons and Mathewson (1955); Marsh 

(1976) provides another general account. Lava flows and 

tuff beds make up the main cone. Flow rocks are mostly 

black to light grey, medium-grained porphyritic andesite 

and basalt (figs. 87, 88) displaying little or no flow 

structure; Marsh (1976) classifies the rocks as andesites 

and basaltic andesites. Phenocrysts include plagioclase, 

calcium-rich pyroxene, olivine, and magnetite. Local 

pyrite impregnation and plagioclase alteration probably 

indicates former solfataric activity at one site on the 

southeast flank. Flow rocks at the summit are also altered. 

The crater dome is a black vitrophyric andesite.

Pumice erupted during caldera formation is buff to 

light brown-grey. The tephra blanket contains fragments 

up to 10 cm in diameter. The ejecta contains crystals of 

plagioclase, pyroxene and amphibole set in a matrix of 

pale glass; pyroxene crystals are up to 6 mm across. Minor 

amounts of rock fragments, primarily of two types, are 

mixed in the pumice blanket. A second minor constituent 

of the pumice blanket is lithic fragments of coarse-grained 

cumulative gabbro xenoliths consisting of plagioclase and 

amphibole grains up to 2 cm across, and accessory olivine, 

pyroxene and magnetite.

80
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES of ALASKA

50 55 60 65 70

SiO2 WT.%

75 80

Figure 87. Total alkalies-silica diagram of Great Sitkin 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of 165°W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

O 5

D>

O

O) 

LL 3

45 50 55 60 65 

SiO2 WT.%

70 75

Figure 88. FeO/MgO-silica diagram of Great Sitkin 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of 165°W longitude). Tholeiitic versus colealkaline discriminant line from Miyashiro (1974).

81
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

KANAGA VOLCANO

NONE

STRATOVOLCANO WITHIN CALDERA

KANAGA ISLAND, ONE OF THE ANDREANOF

GROUP NEAR THE CENTER OF THE ALEUTIAN

ARC; 965 KM WEST-SOUTHWEST OF THE TIP OF

THE ALASKA PENINSULA

51°55'N, 177°10'W

1307 M

ADAK

1101-11

177" 12' 177 10' 177 08'

Form and structure

Kanaga Volcano occupies the northern 

corner of Kanaga Island, one of the most 

southerly members of the Aleutian chain. It 

is a symmetric composite cone 1307 m high 

and 4.8 km in diameter at sea level (fig. 89), 

built of interbedded basaltic and andesitic 

lava flows, scoria layers and pyroclastic 

rocks. Mudflow deposits and other 

volcaniclastic rocks occur on the volcano's 

lower slopes. A circular summit crater, 

approximately 200 m across and 60 m deep, 

contains recent deposits of vent agglomerate, and several active fumaroles.

A mantle of volcanic ash and pumice, 

up to 7 m thick, and containing several soil 

horizons, blankets the northern half of the 

island. Most of this deposit was probably 

erupted from Kanaga Volcano, although 

some may be derived from explosive 

eruptions on nearby islands (Coats, 1956a, 

p.74; Fraser and Barnett, 1959, p. 226). A 

thin layer of andesitic and basaltic pumice, 

younger than the ash-and-pumice mantle, 

coats the volcano's upper slopes, and blocks 

of dense basalt occur across the island. 

Fragments of the latter material have 

produced impact craters up to 4 km from the 

summit. Four young andesitic flows extend 

from fissures near the summit of the cone on 

the south, southwest, and northeast flanks 

(unit Qkb, fig. 89).

North Cape

BERING SEA

Cape Miga

Kanaga Island

:::;; _ . i:i : i-)':i-'i -:::;; ' : 

:Tki>-/;/^::;/;:::;/:;::::

51" 56'

51 55'

51 54'

Contour interval 1000 feet From Coals (19S6a)

QUATERNARY

Approximate extent of 1994 blocky lava flows 

Qva (vent)

>>*.:*;--.'-I

:wQkbs: 1906 Basalt flows from Kanaga Volcano

Historic and late prehistoric basalt flows from Kanaga Volcano

Qat Aadesitetuff

I I:: Qtb : .l Basalt flows and tuff breccia from vent near coast

TERTIARY |:;Tkb:;j Olivi 

~^\

ine and hypersthene basalt, and andesite flows

Figure 89. Generalized geologic map of the north end ofKanaga Island 

after Coats (J956a).

82
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Kanaga Volcano is flanked on the south and east by an 

arcuate ridge up to 800 m in elevation; a somma lake, 

2 km in diameter, is situated between Kanaga Volcano and 

the southeast corner of the arcuate ridge. The ridge and 

associated scarp may represent the eroded remnant of a 

caldera rim. Two observations support the caldera origin of 

the ridge. First, although dissected, remnants of the ridge 

are located along 150° of an approximately circular arc and 

the radially outward dip of the comprising flows indicates 

a central source near the present summit of Kanaga 

Volcano. Secondly, a thin (0.6-9 m) but widespread 

blanket of andesitic crystal-lithic tuff (unit Qat, fig. 89) 

occurs over northern Kanaga Island south and east of 

Kanaga Volcano (Coats, 1956a) where relative age and 

lithologic character suggest that it may be the product of a 

caldera-forming eruption.

Coats (1950, 1956a, b) suggested the caldera formed 

through collapse of a Tertiary volcano (Mount Kanaton) 

near the end of Pleistocene time. However, Miller and 

Kirianov (1994) suggested periods of caldera formation on 

Kanaga occurred -6,000, -4,500, and -3,000 yBP based 

on tephrochronology studies on nearby Adak Island.

Precaldera rocks include flows and pyroclastic rocks 

and minor intrusive rocks. Coats (1956a), and Fraser and 

Barnett (1959) have assigned a late Tertiary to Pleistocene 

age to these older rocks. Apparently several episodes of 

volcanism preceded construction of modern Kanaga 

Volcano. Low outward dips imply that most of the older 

rocks were part of a broad, shield-shaped volcano with a 

vent area near the site of Kanaga Volcano. There is, 

however, evidence that at least one composite cone was 

constructed on the site before formation of the caldera, and 

of other vent eruptions from the flanks of the ancient 

volcano (Coats, 1956a).

Evidence of glaciation has not been noted on Kanaga 

Island, although adjacent islands such as Tanaga display 

signs of glacial erosion down to sea level.

Volcanic activity

1763? 1827

1768? 1829

1786? 1904?-May, 1906

1790? 1933?

1791 1993-95

Persistent but relatively mild volcanic activity has 

characterized Kanaga Volcano during the past 200 years. 

"Smoke" was reported above the island in 1790, 1791, 

1827, and 1829; some or all of these accounts may actually 

refer to steam produced by hot springs on or near the cone 

(Coats, 1956a). Activity of an unspecified nature was 

noticed in 1763, 1768, 1786 (Grewingk, 1850, cited in 

Petroff, 1884), and 1933 (Coats, 1950). The most significant volcanic event observed on Kanaga during the 

historical period was a series of lava flows erupted in 1906 

(Coats, 1956a), and possibly earlier in 1904 (Jaggar, 

1927). A trapper living on the island in 1906 experienced 

several earthquakes and witnessed lava pouring down both 

east and west sides of the cone. Coats (1956a) interpreted 

these flows to be the ones now present on the northeast 

and southwest slopes of Kanaga Volcano. Another flow, 

slightly older, is perhaps the result of the poorly documented activity in 1904.

The most recent eruption began in mid-1993 and 

continued intermittently through most of 1995. The 

eruption was characterized by steam and ash plumes rising 

to as high as 7.5 km and drifting a few tens of kilometers 

downwind, lava extrusion within the summit crater, and 

minor avalanching of incandescent debris down the north 

flank reaching the sea in some cases (Neal and others, 

1995 a, b). Strong sulfur odors were detected on occasion 

by ground observers in Adak, 33 km to the east.

Solfataric activity on Kanaga Island has been known 

since the first exploration of the Andreanof group in 1760- 

1764 (Coats, 1956a). Hot springs located at the foot of the 

cone were not found by Coats in 1946, but he did observe 

several conspicuous fumaroles near and in the summit 

crater. The most spectacular of these produces a vapor 

cloud that can be seen on a clear day from Adak, 50 km to 

the east. Several other fumaroles are floored with opaline 

products of rock disintegration. Fissures emitting a variety 

of hot gases (including hydrogen sulfide) are sulfur 

encrusted. The maximum surface temperature measured 

was 104°C (Coats, 1956a). Fumarolic activity was also 

reported in 1951 (Wentworth, 1951, p. 6).

Composition

Geologic mapping and petrographic studies of Kanaga 

Island were conducted in 1946 by R. Coats and in 1952 by 

G. Fraser and F. Barnett. Kanaga Volcano is composed of 

interbedded scoria, tuff breccias, and flows; compositions 

(figs. 90, 91) probably include basalt, andesite, and/or 

basaltic andesite. In general, both older and more recent 

lava flows comprise grey to black vesicular flow rocks 

with glass in the groundmass. Phenocrysts are typically 

zoned plagioclase (up to 4 mm long), smaller grains of 

hypersthene and augite, and accessory magnetite and 

apatite. Some flows contain hornblende, or rarely, olivine.

The two most recent pyroclastic deposits were also 

studied by Coats (1956a). The first, limited in distribution 

to the slopes of Kanaga Volcano, consists of two thin 

pumice layers; the older contains pale gray pumice and the 

younger contains dark grey pumice. The second deposit 

comprises ejecta of basalt blocks, some of which were 

ejected as much as 50 km from the main cone, which

83
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

contain labradorite and augite phenocrysts with accessory 

magnetite in a groundmass of equant feldspar grains and 

pale glass. These tephra deposits predate all but one of the 

four youngest lava flows.

Rocks of the pre-caldera (shield?) volcano apparently 

range from basalt to andesite in composition. Crystallithic tuff, possibly erupted during a caldera-forming 

eruption, is high-SiO2 andesite or dacite in composition.

50 55 60 65 70

SiO2 WT.%

75 80

Figure 90. Total alkalies-silica diagram ofKanaga 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of!65°W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

7

6

O 5

D)

P 4

O

U? 3 

2 

1

45 50 55 60

SiO, WT.%

65 70 75

Figure 91. FeO/MgO-silica diagram ofKanaga volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of oceanic affinity (those located west of 

165°W longitude). Tholeiitic versus calc-alkaline 

discriminant line from Miyashiro (1974).

84
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

TANAGA VOLCANO 

NONE

STRATOVOLCANO WITH TWO FLANKING STRATOVOLCANOES

TANAGA ISLAND, WESTERNMOST OF THE 

ANDREANOF ISLANDS, ABOUT 1024 KM WESTSOUTHWEST OF THE TIP OF THE ALASKA

PENINSULA

51°53'N, 178°08'W 

1806 M

GARELOI ISLAND 

1101-08

Form and structure

Tanaga Volcano is the central and 

highest of three adjacent stratovolcanoes at the northwest end of Tanaga 

Island (fig. 92). The volcano, mostly 

undissected by erosion, has an altitude 

of between 1770 and 1830 m. 

Interbedded lava flows and 

pyroclastics of the upper slopes have 

initial dips as steep as 35° The three 

stratovolcanoes lie unconformably on 

a slightly older series of interbedded 

lava flows and pyroclastics, which 

Fraser and Barnett (1959) suggest are 

of late Tertiary or Pleistocene age. A 

shield-like form is inferred for this 

earlier volcanic center based on 

shallow radial dips. Alternatively, it 

may be that only the lower flanks of 

an old stratovolcano have been 

preserved. Arcuate ridges and scarps 

border the three modern stratovolcanoes on the east and south, features 

that may represent the partial rim of a 

caldera developed in late Pleistocene 

time (Coats, 1950; 1956).

178

-51° 55'

-51° 50'

Contour interval 400 feet 

200 feet (dashed areas)

Tanaga Volcano and the neighboring cones roughly define an east-west 

trend across northern Tanaga Island. 

At least four cones adjacent to Tanaga Volcano apparently 

have been active since the last glaciation. The stratovolcano located 4 km west-southwest of Tanaga Volcano is in 

an older, breached crater. A blanket of fine ash, as much as 

6 m thick covers large areas of Tanaga Island. The ash, 

stratified and intercalated with thin soil layers, may have 

accumulated over a period of several thousand years.

Topography modified from 

U.S. Geological Survey 

Gareloi Island Quadrangle 

map (i ; 250,000 scale)

Figure 92. Topographic map of Tanaga volcano.

The oldest rocks on Tanaga Island comprise a thick 

sequence of unaltered shallow marine and subaerial lava 

flows, tuff breccias, and subordinate interbedded sediments. This series, considered to be of late Tertiary or

85
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

Quaternary age based on microfossils and mollusks (Fraser 

and Barnett, 1959; Marlow and others, 1973), constitutes 

the southern half of the island, and may underlie the 

northern part as well. Though Tanaga was extensively 

glaciated during the Pleistocene morainal material has 

been recognized in high-altitude cols and cirques throughout the northern portion of the island only a few small 

patches of ice remain on the flanks of the dormant easternmost cones.

Volcanic activity

1763-1770? 1829 

June 7, 1791 1914

Few details are available concerning historical activity 

of Tanaga Volcano, and some or all of the events attributed 

to it may have involved adjacent cones in the northwest 

part of the island (Coats, 1950). Tanaga was reported 

active throughout the period 1763-1770. Smoke was noted 

above the island in 1791 and 1829, and a lava flow was 

observed in 1914 (Coats, 1950, table 2).

Composition

The lava flows of northern Tanaga Island range in 

composition from crystal-rich, high-alumina basalt to 

glassy dacite (Coats and Marsh, 1984). The basalts are 

characterized by nearly unzoned phenocrysts of plagioclase (Ang092) and olivine (Fo6573), clinopyroxene 

(En^Wo^) and titanium-magnetite, whereas the andesites 

and dacites have zoned plagioclase (Ang5 65), and 

orthopyroxene (En69) instead of olivine (Coats and Marsh, 

1984). Fraser and Barnett (1959, p. 222) present a single 

chemical analysis of a basalt flow or sill, from the oldest 

rocks on Tanaga Island, having a SiO2 content of 51.8%.

86
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE:

CAVW NUMBER:

GARELOI VOLCANO

MOUNT GARELOI

STRATOVOLCANO

GARELOI ISLAND, NORTHERNMOST OF THE

DELAROF GROUP, ANDREANOF ISLANDS, ABOUT

1062 KM WEST-SOUTHWEST OF THE TIP OF

THE ALASKA PENINSULA

51°47'N, 178°48'W

1573 M

GARELOI ISLAND

1101-07

178 50' 178 45'

Form and structure

Mount Gareloi, which makes up 

most of Gareloi Island, is a stratovolcano 10 km by 8 km in diameter at its 

base (fig. 93) with two summits, 

separated by a narrow saddle. Two 

small glaciers extend northwest and 

southeast from the saddle. The northern, 

slightly higher peak is on the southern 

rim of a crater about 300 m across, 

which contains several active fumaroles. 

Thirteen younger craters, from 80 to 

1600 m in diameter, are aligned along a 

south-southeast trending fissure that 

extends from strandline to the southern 

summit (fig. 93). These craters formed 

during a major explosive eruption in 

1929 that also produced four blocky 

lava flows (unit Ql, fig. 93), and a 

blanket of glassy andesitic tuff that 

covers an area roughly 2.5 x 5 km on 

the volcano's southeast flank (Coats, 

1959).

The intercalated lava flows and 

pyroclastic debris that make up Gareloi 

volcano were produced during two 

periods of activity separated by an 

extended interval of quiescence and 

erosion. Lava flows range from 1 m to 

more than 6 m in thickness; some flows 

of the older sequence appear to have 

originated from flank vents rather than 

from the summit. Some valleys cut in 

older rocks are U-shaped, suggesting 

that the older series is of late Pleistocene age or older. Rocks of the

i

BERING

Gareloi Island

0 .5 1 km

51 50'

51 45'

Contour Interval 500 feet

QUATERNARY

Lava of 1929 eruption

Younger basalt flows

Older basalt flows

Craters formed In 1929 eruption

.- 

< _.-N, Glacier, showing contours

From Coats, 1959

Summit crater cite 

of 1980 eruption

Figure 93. Geologic map ofGareloi Island after Coats (1959).

87
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

younger series are relatively undissected; many appear to 

have been erupted from at or near the summit crater. 

Craters formed during the 1929 eruptions are probably 

only partly of phreatic origin; erupted material includes 

essential, pumiceous glass, and reddened scoria. Lava 

flows that erupted in 1929 emerged at elevations below 

600 m. In 1946, one crater at an elevation of 900 m, 

contained a small, milky blue-green lake, which suggests 

that acid fumaroles were still active in the crater at that 

time (Coats, 1959, p. 253).

Volcanic activity

1760 

1790-92 

1828-29 

1873

1922 Jan. 15, 1982 

1927 Sept. 4, 1987 

Apr. 1929-30 Aug. 17, 1989 

Aug. - Sept. 1980

Volcanic activity has been frequently reported from 

Mount Gareloi since its discovery during the Bering 

Expedition in 1760. "Smoke" or unspecified activity was 

noted in 1760, 1828 and 1873, and 1927; lava extrusion in 

1792; minor explosive eruptions in 1790 and 1791; and 

major explosive eruptions in 1922 and 1929-30 (Coats, 

1950; 1959). The 1929 event is the most violent on record 

for Gareloi volcano; its course can be reconstructed in 

some detail from a second-hand report of what was 

apparently an eyewitness account (Coats, 1959, p. 252) 

and the findings of Coats' 1946 field examination.

In April of 1929, a phreatic eruption opened an 

elongate crater 1600 m in maximum diameter just below 

the southern summit; further explosions produced 12 

smaller craters aligned along a south- to southeast-trending 

fissure. Glassy pumice, lapilli, scoria, and accidental rocks 

were then ejected from the lower craters, blanketing an 

area roughly 2.5 by 5 km on the southeast slope. Ash 

layers up to 2 m thick on Ogliuga Island, located about 

16 km southeast, may be attributable at least in part to this 

eruption (Coats, 1956, p. 92) and several centimeters of 

pyroclastic debris are known to have fallen on Atka Island 

(about 300 km eastward) during the event. Extrusion of 

lava, which formed short steep flows, occurred at four sites 

along the fissure after the tephra eruptions. Various 

metallic oxides and halides (including atacamite, 

paratacamite and hematite) were deposited in several of 

the lower craters. Activity may have continued into 1930.

Known eruptive activity on Gareloi between 1930 and 

early 1980 was limited to that of fumaroles (Wentworth, 

1951, p. 6) and sulfur dioxide emission at the northern 

summit, and discharge of odorless steam (maximum 

temperature 62°C) from small transverse fissures on the 

southeast flank. In August and September, 1980, eruptions 

were reported at Gareloi volcano (Anchorage Times, 

August 16, and September 19, 1980); the nature of

eruptive activity is uncertain, but apparently it involved 

ash and steam (Smithsonian Institution, 1980).

On January 14, 1982, a magnitude 3.2-3.3 earthquake 

struck the area; the following day, January 15, a 7-9 km 

eruption cloud was observed on satellite imagery 

(Smithsonian Institution, 1982).

On September 4, 1987, a commercial pilot observed a 

narrow flow-like feature on the east flank that extended 

from the north crater rim at 1500 m altitude down to at 

least 1100 m, below which it was obscured by clouds. 

Steam rose 100 m above the flow(?) and the crater was 

vigorously steaming (Smithsonian Institution, 1987). On 

August 17, 1989, a grayish black ash cloud was observed 

from a passing aircraft about 700 m above the volcano's 

summit (Reeder, 1992).

Composition

The only petrographic information currently available 

for Gareloi volcano was obtained by Coats during a brief 

reconnaissance survey in 1946. The older rocks, probably 

late Pleistocene in age, consist of olivine basalt flows, 1 to 

6 m thick, that are commonly holocrystalline and rich in 

augite; coarse reddened scoria is interbedded with exposures on the northeast flank (Coats, 1959, p. 250). Younger 

flows consist of olivine basalt; augite and olivine content 

differ among the flows. Textures range from fine-grained 

with a few small phenocrysts, to seriate and porphyritic.

Juvenile material erupted in 1929 may be significantly 

more siliceous than the older basaltic or basaltic andesite 

rocks. The lava was apparently highly viscous and 

generally formed blocky, vesicular, or scoriaceous flows, 

one of which is 75 m wide and 15m thick. Orthopyroxene, 

brown hornblende, plagioclase (average composition about 

An4g), and clinopyroxene were observed in lava flows and 

pyroclastics of the 1929 eruption (Coats, 1959, p. 254- 

255).
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

SEMISOPOCHNOI VOLCANO 

MOUNT CERBERUS 

INTRACALDERA STRATOCONES 

SEMISOPOCHNOI ISLAND, EASTERNMOST OF THE 

RAT ISLAND GROUP, ANDREANOF ISLANDS, 

ABOUT 1168 KM WEST-SOUTHWEST OF THE TIP 

OF THE ALASKA PENINSULA; THE ISLAND is

LOCATED AT THE JUNCTION OF BOWERS RlDGE 

AND THE INSULAR ALEUTIAN ARC

51°56'N, 179°35'E 

800 M 

RAT ISLANDS 

1101-06

179 30' 179 40'

Form and structure

Mount Cerberus comprises three 

young, relatively undissected 

composite cones (fig. 94), all of 

nearly equal height (800m) and with 

basal diameters somewhat more than 

3 km (Coats, 1959). The cones all 

have summit craters and are built 

principally of andesitic lava flows 

and pyroclastic rocks. The easternmost crater is the smallest and most 

irregular in shape of the three; its 

vent has apparently shifted position 

slightly during or between past 

eruptions. Lava flows appear to have 

originated from flank eruptions 

below 500 m altitude.

About 1.6 km east of Mount 

Cerberus is a partially destroyed 

cone, 260 m above sea level. In the 

northeast part of the caldera, a small 

scoria mound (Lakeshore Cone; unit 

Qbl, fig. 94) was the source of two 

small lava flows 4 km northeast of 

Mount Cerberus, and a small scoria 

and agglutinate mound occurs 1.9 km 

south of Mount Cerberus.

Lava flows (unit Qbc, fig. 94) on 

the north flanks of Mount Cerberus 

appear in general to be younger than 

those on the south flank. The

Petrel Ft North Head

SEMISOPOCHNOI 

ISLAND

BERING SEA

Northeast Ft

Sugarloaf Head

52 00'

51 55'

Contour Interval 500 feet

QUATERNARY

QUATERNARY

OR 

TERTIARY (7)

Mount 

Cerberus

Surficial deposits

Lakeshore 

Cone

Sugarloaf 

Peak

Basaltic tuff-breccia of 

early poatcaldera cone

Lava flows and pyroclastic rocks

From Coats, 1959

Basaltic composite cones 

and lava (lows

Mount Cerberus 

cone* and craters

Pyroclastic rocks and lava flows

Figure 94. Geologic map of Semisopochnoi Island after Coats (1959).

89
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

youngest flow, as distinguished by degree of ash and 

vegetation cover, extends 600 m from the north base of the 

west summit and is probably no more than a century old 

according to Coates (1959). Other individual flows, 

consisting of single or multiple pulses as defined by sets of 

lava levees, can be identified. Many older flows, particularly those on the north flanks of Mount Cerberus, have 

been largely buried beneath loose detrital material washed 

from the upper reaches of the cone.

A widespread blanket of pre-Cerberus dacitic ash, and 

younger andesitic or basaltic ash derived from the eruptions of Cerberus and two neighboring cones, covers much 

of the island. The two neighboring cones Sugarloaf Peak 

and Lakeshore may also have been active in historical 

time (Coats, 1959). The summit of Sugarloaf Peak, 855 m 

high, lies about 4.4 km southeast of Mount Cerberus on 

the south coast of Semisopochnoi Island. Composed 

chiefly of pyroclastics with intercalated lava flows up to 

2m thick (unit Qbs, fig. 94), it has a double parasitic cone 

on its south flank from which vapor is sporadically 

emitted.

The oldest rocks exposed on Semisopochnoi Island 

are deeply eroded remnants of a late Tertiary-early 

Pleistocene volcano that had an eruption center or centers 

somewhere within the central part of the present island. 

These rocks, termed the Pochnoi Volcanics, crop out 

northeast and west of Cerberus (unit Qtpl, fig. 94) (Coats, 

1959). Remnants of composite cones, perhaps slightly 

younger than and parasitic to a main volcano, are exposed 

around the margins of the island (unit Qtp, fig.94). Four 

other cones, one of which may have contained a lava lake 

in its summit crater, and associated lava flows (unit Qlo, 

fig. 94) are distinguishable from the composite cone 

remnants by being less eroded (Coats, 1959). The aforementioned deposits are glacially eroded, although the 

youngest of the cones only slightly so. After glaciation, 

large volumes of dacitic pumice and ash were erupted 

during formation of an elliptic caldera (8 km in greatest 

width) and formed pyroclastic-flow deposits on the flanks 

of the volcano. Deposits of post-caldera, pre-Cerberus 

eruptions are limited to sparse pyroclastic deposits and 

thin flows (unit Qbt, fig. 94) which extend from within the 

caldera out through a breach in the southeast wall. Flows 

from Cerberus and the smaller Lakeshore Cone have 

nearly covered the caldera floor; a small arcuate lake, 2.5 

km long, lies along the inner northeast rim of the caldera. 

Nearly all deposits of Mount Cerberus are contained 

within the southern and western portion of the caldera. 

Flows have breached the southern caldera wall in two 

places and extend 2-5 km to the coast.

Volcanic activity

1772 Sugarloaf? 1987

1790 

1792 

1830 

1873?

Records of volcanism on Semisopochnoi Island are 

scant; historical eruptions could have involved the small 

Lakeshore Cone and Sugarloaf cone in addition to Mount 

Cerberus. However, since at least one of the early reports 

specified that the activity noted was in the center of the 

island, and Mount Cerberus is the least eroded of the 

recent cones, it is believed to have been the source of most 

recorded events (Coats, 1950; 1959). These events include 

emissions of smoke in 1772, 1790, 1792 and 1830 and 

unspecified activity in 1873. In 1947, wisps of steam were 

observed emerging from the vicinity of a parasitic cone on 

the south flank of Sugarloaf Peak (Coats, 1959).

None of the historical activity has been correlated 

with specific lava or pyroclastic deposits on 

Semisopochnoi. However, a young flow on the lower 

northeast flank of Mount Cerberus displays vegetation 

cover comparable to that on a 1906 Kanaga Island flow at 

slightly higher altitude, and was possibly erupted during 

the twentieth century (Coats, 1959, p. 502).

The latest reported activity occurred on April 13, 1987 

when a plume extending 90 km ENE from Semisopochnoi 

Island was observed on satellite imagery; the plume 

extended only 15 km ENE several hours later. On April 24, 

1987, a commercial pilot flying about 50 km SE of the 

Island observed that one of the snow-covered peaks, 

possibly Sugarloaf, was blackened (Smithsonian Institution, 1987).

Composition

The 1947 field studies of Coats provide the most 

detailed petrographic information available for 

Semisopochnoi Island. Mount Cerberus flows comprise 

primarily grey, porphyritic basalt or andesite (figs. 95, 96) 

with phenocrysts of plagioclase, augite, hypersthene and, 

more rarely, olivine. Locally, silicic lava flows of 

hypocrystalline andesite or dacite are intercalated with 

these basalts.

Pyroclastic material erupted from Cerberus is generally similar in composition to the lava flows. Fragments 

are less than 30 cm in diameter. Scoriaceous, dark grey to 

black essential lapilli constitutes about 5% of these 

deposits and small fragments of accessory lithic basalt 

make up most of the rest.

90
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Products of Sugarloaf Cone differ from those of 

Mount Cerberus in that Sugarloaf specimens lack hypersthene, which occurs in every Mount Cerberus sample 

studied (Coats, 1959). Since activity at the two cones 

appears roughly contemporaneous, the cones may tap 

different magma chambers or different parts of the same 

chamber. Most of the Sugarloaf rocks are olivine basalts or 

picritic basalts, that have intergranular textures and 

phenocrysts of labradorite to bytownite plagioclase, 

conspicuous green augite, olivine and magnetite.

Lava flows and pyroclastic deposits of Lakeshore 

Cone were not closely examined by Coats and no petrologic information is available.

Rocks of the volcanic series of Semisopochnoi Island 

range from basalt to dacite (Coats, 1959; DeLong and 

others, 1985) with SiO2 contents of 50.4-65.3% and are 

thoeliitic in character. A composite sample of ash and 

pumice associated with caldera formation has a SiO2 

content of 61.02%; other samples of pumice have SiO2 

contents of 60.22% and 60.98%.

50 55 60 65 70 75 80

Figure 95. Total alkalies-silica diagram of Semisopochnoi 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west ofl65°W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

O 5

D)

P 4

Oo> 

u- 3

45 50 55 60

SiO, WT.%

65 70 75

Figure 96. FeO/MgO-silica diagram of Semisopochnoi 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of 165°W longitude). Tholeiitic versus calcalkaline discriminant line from Miyashiro (1974).

91
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE: 

CAVW NUMBER:

LITTLE SITKIN VOLCANO

LITTLE SITKIN ISLAND

STRATOVOLCANO WITHIN NESTED CALDERAS

LITTLE SITKIN ISLAND, IN THE RAT ISLAND

GROUP OF THE WESTERN ALEUTIAN ISLANDS,

ABOUT 1200 KM WEST-SOUTHWEST OF THE TIP

OF THE ALASKA PENINSULA, AND 76 KM

NORTHWEST OF CONSTANTINE HARBOR ON

AMCHITKA ISLAND

51°57'N, 178°32'E

1188M

RAT ISLANDS

1101-05

178 35'

Form and structure

The active stratovolcano on Little 

Sitkin Island occurs within the eroded 

remnants of a nested double caldera of 

probable late Pleistocene age. The older 

caldera (Caldera One, fig. 97) is about 

4.8 km in diameter and is centered 

slightly northeast of the island's 

midpoint. The caldera formed at the site 

of a large stratovolcano, the remnants 

of which are the oldest rocks exposed 

on the island (unit Qtw, fig. 97; Snyder, 

1959).

A second stratovolcano was 

constructed almost entirely of lava 

flows (unit Qd, fig. 97) within Caldera 

One and attained a height of about 

900 m. A cataclysmic eruption, 

possibly in early post-glacial time, 

resulted in the formation of a second, 

smaller caldera (Caldera Two, fig. 97) 

that partly destroyed this cone. Caldera 

Two is elliptical in outline and measures 2.7 by 4 km; the inferred eastern 

and southern margins are coincident 

with those of Caldera One. Field 

relations suggest that the northern 

boundary of Caldera Two is a hinge 

along which a large block, comprising 

most of the Caldera One stratovolcano, 

was tilted southward during the 

caldera-forming eruption. The highest 

peak on the island is on the postcaldera remnant of the second cone.

51 55'

Contour Interval 500 feet From Snyder (1959)

QUATERNARY

Suiffclal deposits and lc»

Dacite flows

Dacite flows and 

lp pyroclastic material

 -Rhyodactte flow unit

Little Sltkln 

daclte

Ash and pumice of Caldera-Twoformlng eruption_____

[Formation of Caldera Two]

Dacite flows

Andeslte flows

Water-laid pyroclastic material

Fault; long dash where 

approximate, short dash 

where Inferred or concealed

Active fumaiolaa

(Formation ot Celdaie On»|

Pr»-Cald»ia-On» andcilt* flow* 

and pyroclaatlc material

irgln

Figure 97. Geologic map of Little Sitkin Island after Snyder (1959).

93
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES or ALASKA

A deposit of partly welded tuff up to 100 m thick (unit 

Qp, fig. 97) extends from the remnant cone northwest 

across the Caldera Two boundary fault, to slightly beyond 

the inferred location of the Caldera One boundary fault. 

The deposit is thought to have been emplaced by one or 

more pyroclastic flows, possibly associated with formation 

of Caldera Two (Snyder, 1959).

Post-Caldera Two deposits are mainly lava flows 

(units Qls, Qlp, and Qlw, fig. 97). Two relatively recent aa 

flows have well developed levees; one originated from the 

breached central crater of Little Sitkin volcano, and the 

other from a fissure along the western trace of the Caldera 

One boundary fault (Snyder, 1959).

Volcanic activity

1776 

1828-30 

ca. 1900?

Historical records of Little Sitkin volcanism are few 

and fragmentary. A 1776 eruption involving "flames" (C. 

Grewingk, cited in Ball, 1870), attributed to Sitignak, 

probably occurred at Little Sitkin volcano (Coats, 1950). 

Smoke was reported above the island during 1828-30 

(Ball, 1870). Evidence of more recent volcanism is 

provided by Snyder (1959), who mapped two dacitic flows 

on the south and west flanks of the crater that appeared no 

more vegetated at comparable altitudes than andesite flows 

produced during a well-documented 1906 eruption on 

Kanaga Island, 60 km to the west. Snyder (1959, p. 183) 

argues that these extrusions "are not older than" the 1906 

Kanaga flows, implying that Little Sitkin has erupted at 

least once during the 20th century.

Jaggar (1927), states that "Chugul and Little Sitkin are 

said to be fuming volcanoes"; no further details are given.

Current activity on Little Sitkin Island is limited to 

solfataric emissions. Three major fumarolic areas in the 

northwest quarter of the island are aligned parallel to the 

north-northwest trend of neighboring volcanic centers.

Composition

Petrographic data for Little Sitkin volcano are 

presented by Snyder (1959). The oldest rocks on Little 

Sitkin Island are andesitic lava flows, dikes, and pyroclastic deposits, with subordinate amounts of dacitic and 

basaltic lava flows and pyroclastic deposits (figs. 98, 99) 

of an ancestral composite cone. Plagioclase phenocrysts in 

a single sample of basalt range from 45% to 65% Ancontent and from 45% to 60% in a single sample of 

andesite (Snyder, 1959, p. 190-191). Augite exceeds or

equals orthopyroxene in abundance, and olivine occurs in 

trace to accessory amounts in both the basalt and andesite.

Petrographic data on the pyroclastic rocks that may 

have been erupted during formation of Caldera One are 

limited to inclusions of nonporous and pumiceous dacite. 

In the inclusions, plagioclase phenocrysts have an average 

An-content of 45%, quartz is not observed, clinopyroxene 

and orthopyroxene occur in varying proportions, and 

olivine and hornblende are present but uncommon.

The lava flows composing the central cone built 

within Caldera One range in composition from andesite to 

dacite and are characterized by ubiquitous andesitic 

xenoliths. Plagioclase phenocrysts in one specimen of 

andesite range from 26% to 74% in An-content; pleochroic 

brown hornblende, clinopyroxene, orthopyroxene, and 

opaque are the other phenocryst phases. The dacite 

contains plagioclase phenocrysts ranging in An-content 

from 23% to 55%; orthopyroxene, clinopyroxene, hornblende, opaques, and tridymite are the remaining phenocrysts. Trace amounts of olivine occur in other specimens 

of both andesite and dacite that lack tridymite.

Tuffs emplaced during formation of Caldera Two are 

separable into 2 varieties: an upper, light grey to bluegrey, firmly consolidated ash-and-lapilli tuff, and a lower, 

grey-white to salmon-pink welded tuff; both of these are 

probably pyroclastic flow deposits. The upper unit 

contains 1 to 2% angular to subangular blocks of andesite, 

basalt, and dacite up to 60 cm long. The lower unit 

contains 5 to 10% rounded to subrounded bombs(?) 

consisting of black glass with layers, blebs, and stringers 

of white glass. Plagioclase phenocrysts range in Ancontent from 43% to 76%, and abundance of 

clinopyroxene equals or exceeds that of orthopyroxene. 

Olivine, hornblende, and quartz are not known to occur.

Post-Caldera Two lava flows range in composition 

from andesite to dacite or rhyolite. Plagioclase phenocrysts 

in a single sample of andesite range from An35 to An56 ; in 4 

samples of dacite, the range is An^ to An7g . Plagioclase 

phenocrysts in 2 samples of dacite or rhyolite range from 

An27 to An50 and from An35 to An^.

One of the young flows that may have erupted in the 

early 1900's is an andesite or low-silica dacite. Like the 

older, post-Caldera Two low-silica dacites, this sample 

contains plagioclase phenocrysts ranging from An36 to 

An62 .

continued

94
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

45 50 55 60 65 70 75

Figure 98. Total alkalies-silica diagram of Little Sitkin 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of 165°W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

45 50

SiO- WT.%

Figure 99. FeO/MgO-silica diagram of Little Sitkin 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of 165°W longitude). Tholeiitic versus calcalkaline discriminant line from Miyashiro (1974).

97

95
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

NAME AND LOCATION

NAME:

SYNONYMS:

TYPE:

LOCATION:

LATITUDE, LONGITUDE: 

ELEVATION:

USGS 1:250,000 QUADRANGLE:

CAVW NUMBER:

KISKA VOLCANO

NONE

STRATOVOLCANO

KISKA ISLAND, WESTERNMOST OF THE RAT

ISLAND GROUP, IN THE WESTERN ALEUTIAN

ISLANDS: 1270 KM WEST-SOUTHWEST OF THE

TIP OF THE ALASKA PENINSULA, AND ABOUT

400 KM WEST OF ADAK

52°06'N, 177°36'E

1220 M

KISKA

1101-02

BERING 

SEA

Form and structure

Kiska Volcano is a stratovolcano, 

8.5 by 6.4 km in diameter at its base and 

1221 m high, on the northern end of 

Kiska Island. A slightly elliptical crater, 

about 0.4 km in diameter and breached 

on the north, occupies the summit 

(fig. 100). A parasitic 30-m-high cinder 

cone, formed in 1962 near sea level, 

occurs at Sirius Point and an older 

parasitic cone, now levelled by marine 

erosion, occurs at sea level 5.6 km 

southwest of Kiska Volcano.

The southern part of Kiska Island 

has been glacially eroded, but the 

volcano shows no evidence of glacial 

dissection (Coats, 1956). Surface lava 

flows are thus younger than the last 

major glaciation. Five of the youngest 

lava flows (unit Qkr, fig. 100) have been 

mapped separately by Coats and others 

(1961) based on geomorphic expression; 

the flows of block lava have steep fronts 

as much as 30 m high. Source areas of 

the flows range from the base of the 

cone to the summit. The highest flows 

appear to have emerged from the summit 

crater through the breached north wall.

Kiska Volcano is underlain and flanked on the south 

by the remains of an older composite volcano; a single KAr age of 5.5 ± 0.7 m.y. is cited in Marlow and others 

(1973) for an andesitic lava flow in this older volcano.

177 35' 177 40'

Sirius Pt

BERING SEA

KISKA ISLAND

rv

52 07'

52 05'

Contour Interval 500 leet

QUATERNARY

LATE 

TERTIARY

From Coacs and others, 1961

Surficial deposits

Rocks of Kiska Volcano; lava 

flows and interbedded pyroclastic 

depostis, Qk. Youngest flows, Qkr.

Kiska Harbor Formation

Approximate location ol 1862 cinder cone

Figure 100. Geologic map of the north end ofKiska Island 

after Coats and others (1961).

97
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Volcanic activity

1907 

1927 

January 24, 1962

March 18, 1964 

September 11-16, 1969 

April 15, 1987 ? 

June 1, 1990

Records of activity during early historical time are 

scanty; crater solfataric emissions were mentioned as early 

as 1905 and "smoke" was observed over the island in 1907 

and possibly in 1927 (Coats, 1950). Coats briefly visited 

Kiska volcano in 1947 and found no evidence of recent 

ash flows nor any active fumaroles; the youngest lava 

flows were more heavily vegetated at any given altitude 

than counterparts on adjacent islands known to have been 

erupted in the 20th century. The youngest lava flows 

before 1962 were probably between 100 and several 

hundred years old. Coats concluded that any events 

between 1905 and 1947 were at most solfataric (Coats and 

others, 1961).

An explosive eruption occurred on January 24, 1962 

accompanied by lava extrusion and the construction of a 

cinder cone about 30 m high at Sirius Point on the north 

flank of Kiska Volcano, 3 km from the summit of the main 

cone (Anchorage Daily News, January 30, 1962). A second 

eruption that produced a lava flow was reported to have 

occurred March 18, 1964 (Bulletin of Volcanic Eruptions, 

1964). Coast and Geodetic Survey personnel recorded 

renewed activity on Kiska Island in early September, 

1969; an ash column was observed rising to 400 m and 

steam to 4000 m. "Flames" and what appeared to be lava 

were reportedly visible from Amchitka, 80 km distant. On 

September 16, strong sulfur odors, air temperatures 

elevated by 10 to 15°C, and possible evidence of a small 

lava flow were noted during a military flight over north 

Kiska Island (Smithsonian Institution, 1969; eyewitness 

accounts on file at Geophysical Institute, University of 

Alaska, Fairbanks.)

On April 15, 1987, a narrow, drifting plume located 

60 km east of Kiska Island, was observed on satellite 

imagery and is inferred to have originated at Kiska 

volcano (Smithsonian Institution, 1987).

Steam and minor ash emission from an upper flank 

vent on June 1, 1990 was reported by an observer on 

neighboring Amchitka Island (Anchorage Times, June 3, 

1990; Smithsonian Institution, 1990). Although a sizeable 

steam plume was reported during the next several days, 

ash emission apparently lasted only several hours.

Composition

Coats and others (1961) provide the only detailed 

petrographic information available for Kiska Volcano; 

their work is based on reconnaissance studies carried out

in 1947 and 1951. Interbedded lava flows and pyroclastic 

deposits make up the main cone. Both glass and hornblende are reported to occur in the pyroclastic material. 

Lava flows range from less than 1 m to more than 30 m 

thick and are primarily grey, fine-grained porphyritic 

andesite (figs. 101, 102). Some of these rocks contain 

hypersthene and minor olivine; others are two-pyroxene 

andesite. Five of the youngest flows examined by Coats 

and others are medium grey to light brown and consist of 

augite-hypersthene andesite, locally containing minor 

olivine, and basalt.

50 55 60 65 70

Si03 WT.%

75 80

Figuare 101. Total alkalies-silica diagram of Kiska 

volcanic rocks (solid circles) and other Aleutian arc 

volcanic rocks (small dots) of oceanic affinity (those 

located west of 165°W longitude). Discriminant lines and 

field names (Le Bas and others, 1986) are explained on 

Figure 2.

8 

7 

6

O 5

P 4

LU 3

2

1

0

45 50 55 60

SiCL WT.%

65 70 75

Figure 102. FeO/MgO-silica diagram of Kiska volcanic 

rocks (solid circles) and other Aleutian arc volcanic rocks 

(small dots) of oceanic affinity (those located west of 

165°W longitude). Tholeiitic versus calc-alkaline 

discriminant line from Miyashiro (1974).

98
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

REFERENCES

Alaska Sportsman, 1944, From Ketchikan to Barrow: September, 

p. 21.

Alaska Sportsman, August 1949, From Barrow to Ketchikan, p. 

18.

Alaska Volcano Observatory Staff, 1990, The 1989-1990

eruption of Redoubt Volcano: EOS, Transactions, American 

Geophysical Union, v. 71, no. 7, p. 265-275.

Alaska Volcano Observatory, 1993, EOS, Transactions, American 

Geophysical Union, v. 74, no. 19, p. 217.

The Alaskan, Sitka, March 29, 1902.

Anchorage Daily News, August 16 and 19, 1958

Anchorage Times, April 3, July 13, 1935.

Anchorage Times, August 15, 1958; October 17, 1960.

Anchorage Times, February 11, 1963.

Anchorage Times, March 8, 1977.

Anchorage Times, 1990, Kiska volcano rumbles back to life, 

June 3, 1990.

Arce, G.N., 1983, Volcanic hazards from Makushin Volcano, 

northern Unalaska Island, Alaska: unpublished M.S. Thesis, 

University of Alaska, Fairbanks, 142 p.

Arctic Environmental Information and Data Center, 1978,

Aleutian/Pribilof Islands region community profiles (Atka 

Village): Anchorage.

Arculus, R.J., Delong, S.E., Kay, R.W., Brooks, C, and Sun,

S.S., 1977, The alkalic rock suite of Bogoslof Island, eastern 

Aleutian Arc, Alaska: Journal of Geology, v. 85, p. 177-186.

Barnes, I., and McCoy, G.A., 1979, Possible role of mantlederived CO2 in causing two "phreatic" explosions in 

Alaska: Geology, v. 7, p. 434-435.

Bates, R.L., and Jackson, J.A., 1987, Glossary of Geology, Third 

Edition, American Geological Institute, Alexandria, 

Virginia, 788 p.

Becker, G.F., 1898, Reconnaissance of the gold fields of southern 

Alaska, with some notes on general geology: U.S. Geological Survey 18th Annual Report pt. 3, p. 1-86.

Beget, J.E., 1986, Prehistoric tephra eruptions, debris avalanches, 

and tsunamis at Mt. St. Augustine: The geologic record: 

EOS, Transactions, American Geophysical Union, v. 67, p. 

1260.

Beget, J.E., 1996, Dendrochronologic, archeologic, and radiocarbon data on recent eruptions of Iliamna and Augustine 

volcanoes, Alaska [abs]: EOS, Tranasactions, Amer. 

Geophysical Union, v.77, p. F814.

Beget, J.E., and Kienle, Juergen, 1992, Cyclic formation of

debris avalanches at Mount St. Augustine: Nature, v. 356, p. 

701-704.

Benson, C.S. and Motyka, R.J., 1979, Glacier-volcano interactions on Mt. Wrangell, Alaska: in: Annual Report 1977- 

1978: Fairbanks, University of Alaska Geophysical Institute, 

p. 1-25.

Black, R.F., 1974, Late-Quaternary sea level changes, Umnak 

Island, Aleutians their effects on ancient Aleuts and their 

causes: Quaternary Research, v. 4, p. 264-281.

Black, R.F., Dall, W.H., 1870, Alaska and its resources: Reprinted 1970, Arno Press, Inc., 627 p.

Black, R.F., 1975, Late-Quaternary geomorphic processes: 

effects on the ancient Aleuts of Umnak Island in the 

Aleutians: Arctic, v. 28, p. 159-169.

Brantley, S.R., ed., 1990, The eruption of Redoubt Volcano,

Alaska, December 14, 1989-August 31, 1990: U.S.

Geological Survey Circular 1061, 33 p. 

Bulletin of Volcanic Eruptions, 1963: Volcanological Society of

Japan, no. 3, p. 3. 

Bulletin of Volcanic Eruptions, 1964: Volcanological Society of

Japan, no. 4. 

Bulletin of Volcanic Eruptions, 1987: Volcanological Society of

Japan, no. 24, p. 36-37. 

Bulletin of Volcanic Eruptions, 1987: Volcanological Society of

Japan, no. 24, p. 55-56. 

Burk, C.A., 1965, Geology of the Alaska Peninsula-island arc

and continental margin (Part I): Geological Society of

America Memoir, 99, 250 p. 

Byers, P.M., Jr., and Brannock, W.W., 1949, Volcanic activity on

Umnak and Great Sitkin Islands, 1946-1948: EOS,

Transactions, American Geophysical Union, v. 30, no. 5, p.

719-734. 

Byers, P.M., 1959, Geology of Umnak and Bogoslof Islands,

Aleutian Islands, Alaska: U.S. Geological Survey Bulletin

1028-L, p. 167-369. 

Byers, P.M., Jr., 1961, Petrology of three volcanic suites, Umnak

and Bogoslof Islands, Aleutian Islands, Alaska: Geological

Society of America Bulletin, v. 72, p. 93-128. 

Byers, P.M., Jr., and Earth, T.F.W., 1953, Volcanic activity on

Akun and Akutan Islands, Alaska: Pacific Science Congress,

7th, New Zealand, 1949, Proceedings, v.2, p. 382-397. 

Capps, S.R., 1929, The Mount Spurr region, Alaska: U.S.

Geological Survey Bulletin 810-C, p. 140-172. 

Casadevall, T.J., 1994, The 1989-90 eruption of Redoubt

Volcano, Alaska: Impacts on aircraft operations. T.P. Miller

and B.A. Chouet (Editors), The 1989-90 eruptions of

Redoubt volcano, Alaska: Journ. of Volcan.and Geotherm

Res. v. 62, p. 301-316. 

Coats, R.R., 1950, Volcanic activity in the Aleutian arc: U.S.

Geological Survey Bulletin 974-B, p. 35-47. 

Coats, R.R., 1952, Magmatic differentiation in tertiary and

Quaternary volcanic rocks from Adak and Kanaga Islands,

Aleutian Islands, Alaska: Geological Society of America

Bulletin, v. 63, p. 485-514. 

Coats, R.R., 1956a, Geology of northern Kanaga Island, Alaska:

U.S. Geological Survey Bulletin 1028-D, p. 69-81. 

Coats, R.R, 1956b, Reconnaissance geology of some western

Aleutian Islands, Alaska: U.S. Geological Survey Bulletin

1028-E, p. 83-100. 

Coats, R.R., 1959, Geological reconnaissance of Sernisopochnoi

Island, western Aleutian Islands, Alaska: U.S. Geological

Survey Bulletin 1028-O, p. 477-519. 

Coats, R.R., 1959, Geologic reconnaissance of Gareloi Island,

Aleutian Islands, Alaska: U.S. Geological Survey Bulletin

1028-J, p. 249-256. 

Coats, R.R., and Marsh, B.D., 1984, Reconaissance geology and

petrology of northern Tanaga, Aleutian Islands, Alaska:

Geological Society of America Abstracts with Programs, v.

16, no. 6, p. 474. 

Coats, R.R., Nelson, W.H., Lewis, R.Q., and Powers, H.A., 1961,

Geologic reconnaissance of Kiska Island, Aleutian Islands,

Alaska: U.S. Geological Survey Bulletin 1028-R, p. 563-

581.

99
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES or ALASKACurtis, G.H., 1968, The stratigraphy of the ejecta from the 1912 

eruption of Mount Katmai and Novarupta, Alaska: Geological Society of America Memoir 116, p. 153-210.

Dall, W.H., 1918, Reminiscences of Alaskan volcanoes: The 

Scientific Monthly, v. VII, p. 80-90.

Davidson, George, 1884, Notes on the volcanic eruption of

Mount St. Augustine, Alaska, Oct. 6, 1883: Science, v. 3, p. 

186-189. (See also Science, v. 3, p. 798.)

Davidson, George, 1892, The eruption of the volcano Veniaminof 

(sic): Transactions and Proceedings of the Geographical 

Society of the Pacific, v. 3, p. 59-62.

Davies, J.N Sykes, Lyn, House, L., and Jacob, Klaus, 1981, 

Shumagin seismic gap, Alaska Peninsula: History of great 

earthquakes, tectonic setting, and evidence of high seismic 

potential: Journal of Geophysical Research, v. 86, p. 3821- 

3855.

Davies, J.N., Taber, John, Miller, T.P., Power, J.A., and Yount, 

M.E., 1988, Seismicity and geology of Mt. Dutton, a 

volcano near the tip of the Alaska Peninsula: American 

Geophysical Union Abstracts with Programs, v. 69, n. 44, p. 

1507.

Decker, R.W., 1967, Investigations at active volcanoes: U.S. 

National Report, 1963-1967, Adams, L.H., and Schairer, 

J.F., eds., EOS, Transactions, American Geophysical Union, 

v. 48, no. 2, p. 639-647.

DeLong, S.E., Perfit, M.R., McCulloch, and Ach, Jay, 1985, 

Magmatic evolution of Semisopochnoi Island, Alaska: 

Journal of Geology, v. 93, n.5, p. 609-619.

Detterman, R.L., 1968, Recent volcanic activity on Augustine 

Island, Alaska: U.S. Geological Survey Professional Paper 

600-C, p. C126-129.

Detterman, R.L., 1973, Geologic map of the Hiamna B-2 

quadrangle, Augustine Island, Alaska: U.S. Geological 

Survey Geologic Quadrangle Map GQ-1068, 1 sheet, scale 

1:63,360, 4 p.

Detterman, R.L., and Hartsock, J.K., 1966, Geology of the 

Iniskin-Tuxedni region, Alaska: U.S. Geological Survey 

Professional Paper 512, plate 1.

Detterman, R.L., Miller, T.P., Yount, M.E., and Wilson, F.H., 

1981, Geologic map of the Chignik and Sutwik Island 

quadrangles, Alaska: U.S. Geol. Survey Miscellaneous 

Investigations Map 1-1229.

Detterman, R.L., Miller, T.P, Yount, M.E., and Wilson, F.H., 

1981, Quaternary geologic map of the Chignik and Sutwik 

Island quadrangles, Alaska: U.S. Geological Survey 

Miscellaneous Investigations Map 1292, scale 1:250,000.

Detterman, R.L., Case, J.E., Wilson, F.H., Yount, M.E., and 

Allaway, Jr., W.H., 1983, Generalized geologic map, 

Ugashik, Bristol Bay, and part of Karluk quadrangless, 

Alaska: U.S. Geological Survey Miscellaneous Field Studies 

Map MF-1539-A, 1:250,000 scale.

Detterman, R.L., Wilson, F.H., Yount, M.E., and Miller, T.P,

1987, Quaternary geologic map of the Ugashik, Bristol Bay, 

and western part of Karluk quadrangles, Alaska: U.S. 

Geological Survey Miscellaneous Investigations Map I1801, 1:250,000 scale.

Doroshin, P., 1870, Some volcanoes, their eruptions, and

earthquakes in the former Russian holdings in America: zu 

St. Petersburg, Zweite Serie, Funfter Rand, 25-44 (in 

Russian).

Drewes, Harald, Fraser, G.D., Snyder, G.L., Garnett, H.F., Jr., 

1961, Geology of Unalaska Island and adjacent insular 

shelf, Aleutian Islands, Alaska: U.S. Geological Survey 

Bulletin 1028-S, p. 583-676.

Eakle, A.S., 1908, Recent volcanic eruptions in the Bering Sea: 

Mining and Scientific Press, v. 96, p. 353.

Eichelberger, J.C., Keith, T.E.C., Miller, T.P, and Nye, C.J.,

1995, The 1992 eruptions of Crater Peak vent, Mount Spunvolcano, Alaska: Chronology and summary. In T.E.C. Keith 

(Editor), The 1992 eruptions of Crater peak vent, Mount 

Spurr volcano, Alaska: U.S. Geological Survey Bulletin 

2139, p. 1-18.

Fenner, C.N. 1920, The Katmai region, Alaska, and the great 

eruption of 1912: Journal of Geology, v. 28, no. 7, p. 569- 

606.

Fenner, C.N., 1925, Earth movements accompanying the Katmai 

eruption: Pt. I. Regional earthquakes, Pt. II. Fracturing in the 

Valley of Ten Thousand Smokes: Journal of Geology, v. 33, 

p. 116-139, 193-223.

Fenner, C.N., 1926, The Katmai magmatic province: Journal of 

Geology, v. 34, p. 673-772.

Fenner, C.N., 1930, Zeitschrift fur Vulkanologie, v.132, p. 1-24.

Fierstein, Judy, and Hildreth, Wes, 1992, The plinian eruptions of 

1912 at Novarupta, Katmai National Park, Alaska: Bulletin 

of Volcanology, v. 54, p. 646-684.

Finch, R.H., 1934, Shishaldin Volcano: Proceedings of the Fifth 

Pacific Science Conference, Canada, v. 3, p. 2369-2376.

Finch, R.H., 1935, Akutan Volcano: Zeitschrift fur Vulkanologie, 

Band XVI, p. 155-160.

Forbes, R.B., Ray, D.K., Katsura, T, Matsumoto, H., Haramura, 

H. and Furst, M.J., 1969, The comparative chemical 

composition of continental vs. island arc andesites in 

Alaska: Oregon Department of Geology and Mineral 

Industries Bulletin 65, 111-120.

Fournelle, J.H., 1988, Geology and petrology of Shishaldin 

Volcano, Unimak Island, Aleutian arc, Alaska: The Johns 

Hopkins University, unpublished Doctoral Dissertation, 507

PFournelle, J.H., 1990, Geology and geochemistry of Fisher 

Caldera, Unimak Island, Aleutians [abs.]: EOS, Transactions, American Geophysical Union, v. 71, n. 43, p. 1698- 

1699.

Fournelle, J.H., Marsh, B.D., and Myers, J.D., 1994, Age, 

character, and significance of Aleutian arc volcanism: In 

George Plafker and H.C. Berg (Editors), The Geology of 

Alaska, Geological Society of America, Decade of North 

American Geology, v. Gl, p. 723-758.

Fraser, G.D., and Barnett, H.F., 1959, Geology of the Delarof and 

westernmost Andreanof Islands, Aleutian Islands, Alaska: 

U.S. Geological Survey Bulletin 1028-1, p. 211-148.

Freiday, Dean, 1945, The Aleutians Island necklace of the 

North: Natural History, v. 54, p. 444-455.

Gardner, C.A., Neal, C.A., Waitt, R.B., and Janda, R.J., 1994, 

Proximal pyroclastic deposits from the 1989-90 eruption of 

Redoubt Volcano, Alaska: Stratigraphy, distribution, and 

physical characteristics. In T.P. Miller and B.A. Chouet 

(Editors), The 1989-90 eruptions of Redoubt volcano, 

Alaska: Journal of Volcanology and Geothermal Research, 

v. 62, p. 213-250.

Goodliffe, A.M., Stone, D.B., and Kienle, Juergen, 1991, The 

vent of the 1912 Katmai eruption: Gravity and magnetic 

measurements: Geophysical Research Letters, v. 18, no. 8, 

p. 1521-1524.

100
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Grewingk, Constantine, 1850, Beitrag zur Kenntniss der 

orographischen und geognostischen Beschaffenheit der 

Nordwestkuste Amerikas, mit den angliegenden Inseln 

(Contribution to knowledge of the orographic [topographic] 

and geognostic [geologic] condition of the northwest coast 

of America with adjacent islands): Abstracted from 

Verhandlungen der Russich-Kaiserlichen Mineralogischen 

Gesellschalt zur St. Petersburg, Janrgan 1848 ung 1849, p. 

76-342.

Griggs, R.F., 1922, The Valley of Ten Thousand Smokes: 

Washington, D.C., National Geographic Society, 340 p.

Hantke, Gustav, 1951, Uebersicht uber die vulkanische tatigkeit, 

1941-1947: Bulletin Volcanologique, v. 11, p. 161-208.

Harbin, M.L., 1994, Observations of the 1992 lava dome,

Bogoslof Island, Eastern Aleutian arc, Alaska [abs.]: EOS, 

Transactions, American Geophysical Union, 1994 Fall 

Meeting, v. 75, n. 44, p. 737.

Henning, R.A., Rosenthal, C.H., Olds, B., and Reading, E., 1976, 

Bogoslof Island, in Alaska's Volcanoes: Alaska Geographic, 

v. 4, p. 45-58.

Hildreth, Wes, 1983, The compositionally zoned eruption of 1912 

in the Valley of Ten Thousand Smokes, Katmai National 

Park, Alaska: Journal of Volcanology and Geothermal 

Research, v. 18, p. 1-56.

Hildreth, Wes, 1987, New perspectives on the eruption of 1912 in 

the Valley of Ten Thousand Smokes, Katmai National Park, 

Alaska: Bulletin of Volcanology, v. 49, p. 680-693.

Hildreth, Wes, 1991, The timing of caldera collapse at Mount 

Katmai in response to magma withdrawal toward Novarupta: Geophysical Research Letters, v. 18, 1541-1544.

Hubbard, B.R., 1931, A world inside a mountain, the new

volcanic wonderland of the Alaska Peninsula, is explored: 

National Geographic Society, v. 60, no. 9, p. 319-345.

Jaggar, T.A., 1927, Eruption of Mageik in Alaska: The Volcano 

Letter, no. 147, p. 1.

Jaggar, T.A., 1929, Mapping the home of the great brown bear: 

National Geographic, v. 55, no. 1, p. 109-134.

Jaggar, T.A., 1930, Recent activity of Bogoslof volcano: The 

Volcano Letter, no. 275, p. 1-3.

Jaggar, T.A., 1931, Difficulties of Alaskan earthquake study: The 

Volcano Letter, no. 337, p. 1-3.

Jaggar, T.A., 1932, Aleutian eruptions 1930-32, The Volcano 

Letter, no. 375, p. 1-3.

Johnston, D.A., 1979, Volcanic gas studies at Alaskan volcanoes, 

in Alaska, Accomplishments During 1978: U.S. Geological 

Survey Circular 804-B, p. B83-B84.

Johnston, D.A., 1979, Onset of volcanism at Augustine Volcano, 

lower Cook Inlet: in Johnson, K.M., and Williams, J.R., 

eds., The United States Geological Survey in Alaska: 

Accomplishments during 1978: U.S. Geological Survey 

Circular 804-B, p. B78-B80.

Johnston, D.A., and Detterman, R.L., 1979, Revision of the 

recent eruption history of Augustine Volcano elimination 

of the "1902 eruption" in Johnson, K.M., and Williams, J.R., 

eds., The United States Geological Survey in Alaska: 

Accomplishments during 1978: U.S. Geological Survey 

Circular 804-B, p. B80-B83.

Juhle, Werner and Coulter, H.W, 1955, The Mount Spuneruption, July 9, 1953: EOS, Transactions American 

Geophysical Union, v. 36, p. 199-202.

Kamata, Hiroki, Johnston, D.A., and Waitt, R.B., 1991, Stratigraphy, chronology, and character of the 1976 pyroclastic 

eruption of Augustine volcano, Alaska: Bulletin of Volcanology, v. 53, p. 407-419.

Kay, S.M., Kay, R.W, and Citron, G.P., 1982, Tectonic controls 

on tholeiitic and calc-alkaline magmatism in the Aleutian 

Arc: Journal of Geophysical Research, v. 87, no. B5, p. 

4051-4072.

Kay, R.W, 1990, Kastaochi: central Aleutian Islands, in C.A. 

Wood and Juergen Kienle, eds., Volcanoes of North 

America, Cambridge University Press, p. 28.

Kennedy, G.C., and Waldron, H.H., 1955, Geology of Pavlof 

volcano and vicinity, Alaska: U.S. Geological Survey 

Bulletin 1028-A, 19 p.

Kienle, Juergen, and Shaw, G.E., 1979, Plume dynamics, thermal 

energy and long distance transport of Vulcanian eruption 

clouds from Augustine Volcano, Alaska: Journal of 

Volcanology and Geothermal Research, v. 6, p. 139-164.

Kienle, Juergen, Kyle, PR., Self, Stephen, Motyka, R.J., and 

Lorenz, Volker, 1980, Ukinrek Maars, Alaska, I. April 1977 

eruption sequence, petrology and tectonic setting: Journal of 

Volcanology and Geothermal Research, v. 7, p. 11-37.

Kienle, Juergen and Swanson, S.E., 1985, Volcanic hazards from 

future eruptions of Augustine Volcano, Alaska: University of 

Alaska Geophysical Institute Report, UAG R-275, 122 p.

Kienle, Juergen, Davies, J.N., Miller, T.P, and Yount, M.E., 

1986, (The) 1986 eruption of Augustine Volcano: Public 

safety response by Alaskan volcanologists: EOS, Transactions, American Geophysical Union, v. 67, no. 29, p. 580- 

582.

Kienle, Juergen, Kowalik, Zygmunt, and Murty, T.S., 1987,

Tsunamis generated by eruptions from Mount St. Augustine 

volcano, Alaska: Science, v. 236, p. 1442-1447.

Kienle, Juergen, and Swanson, S.E., 1983, Volcanism in the

eastern Aleutian arc: Late Quaternary and Holocene centers, 

tectonic setting, and petrology: Journal of Volcanology and 

Geothermal Research, v. 17, p. 393-432.

Kosco, D.G., 1981, Part I: The Mt. Edgecombe volcanic field, 

Alaska: An example of tholeiitic and calc-alkaline volcanism, Part II: Characteristics of andesitic to dacitic volcanism 

at Katmai National Park, Alaska: Unpublished Ph.D. 

dissertation, University of California, Berkeley, 249 p.

Lamb, Drew, Linneman, S.R., Myers, J.D., and Nicolaysen, K.E., 

1992, Caldera formation on Yunaska Island, central Aleutian 

arc: EOS, Transactions, American Geophysical Union, 

1992, Fall Meeting, v. 73, no. 43, p. 645.

LeBas, M.J., LeMaitre, R.W, Streckeisen, A., and Zanettin, B., 

1986, A chemical classification of volcanic rocks based on 

the total alkali-silica diagram: Journal Petrology, v. 27, part 

3, p. 745-750.

Lowney, P. B., 1946, Angry earth: Alaska Life, April.

Marlow, M.S., Scholl, D.W., Buffmgton, E.G., and Alpha, T.R., 

1973, Tectonic history of the central Aleutian arc: Geological Society of America Bulletin, v. 84, p. 1555-1574.

Marsh, B.D., 1976, Some Aleutian andesites: Their nature and 

source: Journal of Geology, v. 84, p. 27-45.

Marsh, B.D., 1990, Atka, Central Aleutian Islands, in, Wood, 

C.A., and Kienle, Juergen, eds., Volcanoes of North 

America, Cambridge University Press, New York, NY, p. 

29-31.

101
CATALOG or THE HISTORICALLY ACTIVE VOLCANOES or ALASKAMartin, G.C., and Katz, F.J., 1912, A geologic reconnaissance of 

the Iliamna region, Alaska: U.S. Geological Survey Bulletin 

485, 138 p.

Matumoto, Tosimatu, and Ward, P.L., 1967, Microearthquake 

study of Mt. Katmai and vicinity, Alaska: Journal of 

Geophysical Research, v. 72, p. 2557-2568.

McGimsey, R.G., 1995, Report on Westdahl volcano: In Bulletin 

of Volcanic Eruptions, 1992, v. 32, p. 92-94.

McGimsey, R.G., Richter, D.H., DuBois, G.D., and Miller, T.P., 

1992, A postulated new source for the White River Ash, 

Alaska, in Bradley, D.C., and Ford, A.B., eds., Geologic 

Studies in Alaska by U.S. Geological Survey, 1990: U.S. 

Geol. Survey Bulletin 1999, p. 212-218.

McLean, H., Engelhardt, C.L., and Howell, D.G., 1978, Reconnaissance geologic map of the Cold Bay and False Pass 

quadrangles, Alaska: U.S. Geological Survey Open-file 

Report, 78-323, 1 pi.

McNutt, S.R., 1987, Eruption characteristics and cycles at Pavlof 

Volcano, eastern Aleutians, and their relation to regional 

earthquake activity: Journal of Volcanology and Geothermal 

Research, v. 31, p. 239-267.

McNutt, S.R., Miller, T.P, and Taber, J.J., 1991, Geological and 

seismological evidence of increased explosivity during the 

1986 eruptions of Pavlof Volcano, Alaska: Bulletin of 

Volcanology, v. 53, p. 86-98.

McNutt, S.R., Tytgat, Guy, and Power, J.A., Preliminary analysis 

of volcanic tremor associated with the 1992 eruptions of 

Crater Peak, Mt. Spurr, Alaska. In T.E.C. Keith (Editor), The 

1992 eruptions of Crater Peak vent, Mount Spurr volcano, 

Alaska. U.S. Geological Survey Bulletin 2139, p. 161-178.

Mendenhall, W.C., 1905, Geology of the central copper River 

region, Alaska: U.S. Geological Survey Professional Paper 

41, 133 p.

Mendenhall, WC. and Schrader, F.C., 1903, The mineral 

resources of the Mt. Wrangell district, Alaska: U.S. 

Geological Survey Professional Paper, 15, 71 p.

Miller, T.P, in press, Geology of the Ugashik-Mount Peulik 

volcanic center, Alaska Peninsula: U.S. Geol. Survey Map.

Miller, T.P, and Kirianov, VYu., 1994, Timing of large Holocene 

Volcanic events in the western Aleutian arc, Alaska [abs.]: 

EOS, Transactions, American Geophysical Union, v. 75, n.

44. p. 731.

Miller, T.P, and Smith, R.L., 1977, Spectacular mobility of ash 

flows around Aniakchak and Fisher calderas, Alaska: 

Geology, v. 5, p. 173-176.

Miller, T.P, and Smith, R.L., 1975, Two caldera-forming

eruptions on Umnak Island, eastern Aleutian Islands: The 

United States Geological Survey in Alaska: Accomplishments during 1975: U.S. Geological Survey Circular 733, p

45.

Miller, T.P, and Smith, R.L., 1987, Late Quaternary calderaforming eruptions in the eastern Aleutian arc, Alaska: 

Geology, v. 15, p. 434-438.

Miller, T.P, and Chouet, B.A., 1994, An introduction and 

chronology to the 1989-90 eruption of Redoubt Volcano, 

Alaska. In T.P. Miller and B.A. Chouet (Editors), The 1989- 

90 eruptions of Redoubt volcano, Alaska: Journal Volcanology and Geothermal Research, v.62, nos. 1-4, p.l -10.

Miller, T.P, Neal, C.A., and Waitt, R.B., 1995, Pyroclastic flows 

of the 1992 Mt. Spurr eruptions: Distribution and origin. In 

T.E.C. Keith (Editor), The 1992 eruptions of Crater Peak 

vent, Mount Spurr volcano, Alaska: U.S. Geological Survey 

Bulletin 2139, p. 81-88.

Miyashiro, Akiho, 1974, Volcanic rock series in island arcs and 

active continental margins: Amer. Jour, of Science v. 274, p. 

321-355.

Moodie, D.W., Catchpole, A.J.W., and Abel, Kerry, 1992, 

Northern Athapaskan oral traditions and the White River 

volcano: Ethnohistory, v. 39, n. 2, p. 148-171.

Motyka, R.J., and Benson, C.S., 1975, Recent investigations on 

the crater lake, Katmai Caldera, Alaska [abs]: Transactions, 

American Geophysical Union, v. 56, no. 12, p. 1072-1973.

Motyka, R.J., Liss, S.A., Nye, C.J., and Moorman, M.A., 1993, 

Geothermal resources of the Aleutian arc: Alaska Division 

of Geological and Geophysical Surveys Professional Report 

114, 17 p.

Muller, E.H., Juhle, Werner, and Coulter, H.W., 1954, Current 

volcanic activity in Katmai National Monument (Alaska): 

Science, v. 119, no. 3088, p. 319-321.

Myers, J.D., and Singer, B.S., 1987, Sequam Island, central 

Aleutian Islands, Alaska: I. Geologic field relations: EOS, 

Transactions, American Geophysical Union, v. 68, no. 44, p. 

1525.

Neal, C.A., McGimsey, R.G., Braitseva, O.A., Miller, T.P, 

Eichelberger, J.C., and Nye, C.J., 1992, Post-caldera 

eruptive history of Aniakchak caldera, Alaska: EOS, 

American Geophysical Union Transactions, v. 73, no. 43, p. 

645.

Neal, C.A., McGimsey, R.G., Gardner, C.A., Harbin, M.L., and 

Nye, C.J., 1994, Tephra-fall deposits from the 1992 

eruptions of Crater Peak, Spurr Volcano, Alaska: A preliminary report on distribution, stratigraphy, and composition. In 

T.E.C. Keith (Editor), The 1992 eruptions of Crater Peak 

vent, Mount Spurr volcano, Alaska: U.S. Geological Survey 

Bulletin 2139, p. 65-80.

Neal, C.A., and McGimsey, R.G., 1997, 1996 volcanic activity in 

Alaska and Kamchatka: summary of events and response of 

the Alaska Volcano Observatory: U.S. Geol. Survey OpenFile Report 97-433, 41 p.

Newhall, C.G., and Dzurisin, D., 1987, Historical Unrest at large 

calderas of the world: U.S. Geological Survey Bulletin 

1855, v. 2, p. 721-731.

Nicolaysen, K.E., Myers, J.D., Linneman, S.R., and Lamb, Drew, 

1992, Geologic Relations of the Yuanaska volcanic 

complex, central Aleutian arc: EOS, Trans. Amer. Geophysical Union, 1992 Fall Meeting, p. 645.

Nicolaysen, K.E., Myers, J.D., and Frost, C.D., 1994, Geochemical and isotopic evidence for magma recharge, Yunaska 

Island, Central Aleutian Arc, Alaska: v. 75, n. 16, p. 366.

Nye, C.J., 1983, Petrology and geochemistry of Okmok and 

Wrangell Volcanoes, Alaska: Ph.D dissertation Univ. of 

California, Santa Cruz, 208p.

Nye, C.J., 1986, Volcanic hazards constraints, in Engineering 

Geology Technical feasibility study, Makushin geothermal 

power project, Unalaska, Alaska: Alaska Division of 

Geological and Geophysical Surveys, Public Data File 86- 

60, p. El-Ell.

Nye, C.J., 1987, Stratigraphy, petrology, and geochemistry of the 

Spurr volcanic complex, eastern Aleutian arc, Alaska: 

University of Alaska Fairbanks, Geophysical Institute 

Report, UAGR-311, 134 p.

Nye, C.J., 1990, Makushin: eastern Aleutian Islands, in, C.A. 

Wood and Juergen Kienle, eds., Volcanoes of North 

America, Cambridge University Press, p. 41-43.

102
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA

Nye, C.J., and Reid, M.R., 1985, Geochemistry of primary and 

least fractionated lavas from Okmok volcano, central 

Aleutians: Implications for arc magmagenesis: Journal of 

Geophysical Research, v. 91, n. BIO, p. 10,271-10,287.

Nye, C.J., and Turner, D.L., 1990, Petrology, geochemistry, and 

age of the Spurr volcanic complex, eastern Aleutian arc: 

Bulletin of Volcanology, v. 52, p. 205-226.

Nye, C.J., Harbin, M.L., Miller, T.P., Swanson, S.E., and Neal, 

C.A., 1995, Whole-rock major- and trace-element chemistry 

of 1992 ejecta from Crater Peak, Mt. Spurr, Alaska: A 

preliminary overview: In T.E.C. Keith (Editor), The 1992 

eruptions of Crater Peak vent, Mount Spurr volcano, Alaska: 

U.S. Geological Survey Bulletin, 2139, p. 119-128.

Nye, C.J., Swanson, S.E., Avery, V.F., and Miller, T.P., 1994, 

Geochemistry of the 1989-90 eruption of Redoubt Volcano: 

Part I. Whole-rock major and trace element chemistry. In: 

T.P Miller and B.A. Chouet (Editors), The 1989-90 

eruptions of Redoubt volcano, Alaska: Journal of Volcanology and Geothermal Research v. 62, p. 429-452.

Nye, C.J., Quenn, L.D., and Motyka, R.J., 1984, Geologic map of 

the Makushin geothermal area, Unalaska Island, Alaska: 

Alaska Div. Geol. Geophys. Surv. report of Invest. RI-84-3, 

2 sheets, 1:24,000.

Ort, M.H., Neal, C.A., McConnell, VS., Wohletz, K.H., Duffield, 

W.A., and Lescinsky, D.T., 1993, Effects of prevailing wind 

on the distribution of surge and fallout deposits at Ukinrek 

Maars, Alaska: EOS, Transactions, American Geophysical 

Union, v. 74, no. 43, p. 639.

Orth, D.J., 1967, Dictionary of Alaska place names: U.S. 

Geological Survey Professional Paper 567, 1084 p.

Petroff, Ivan, 1884, Alaska: It's population, industries, and 

resources: U.S. Bureau of Census, 276 p.

Power, J.A., Jolly, A.D., Page, R.A., andMcNutt, S.R., 1995, 

Seismicity and forecasting of the 1992 eruptions of Crater 

Peak vent, Mt. Spurr, Alaska: An overview. In T.E.C. Keith 

(Editor), The 1992 eruptions of Crater Peak vent, Mount 

Spurr volcano, Alaska: U.S. Geological Survey Bulletin 

2139, p. 149-160.

Powers, H.A., 1958, Alaska Peninsula-Aleutian Islands, p. 61-75, 

in Williams, Howel (ed.), Landscapes of Alaska: Their 

geologic evolution: University of California, Berkeley, 148

PRay, D.K., 1967, Geochemistry and petrology of the Mt. Trident 

andesites, Katmai National Monument, Alaska: Unpublished 

Ph.D. dissertation, University of Alaska, Fairbanks, 198 p.

Reeder, J.W., 1983, Preliminary dating of the caldera forming 

Holocene volcanic events for the eastern Aleutian Islands 

[abs.]: Geological Society of America Abstracts with 

Programs, v. 15, p. 668.

Reeder, J.W, 1988, Report on Korovin volcano: in Bulletin of 

Volcanic Eruptions, v. 50, p. 55-56.

Reeder, J.W., 1992, Report on Gareloi volcano: in Bulletin of 

Volcanic Eruptions, v. 29, p. 70.

Richter, D.H., Preece, S.J., McGimsey, R.G., and Westgate, J.A., 

1995, Mount Churchill, Alaska: source of the late Holocene 

White River Ash: Canadian Journal of Earth Science, v. 32, 

p. 741-748.

Richter, D.H., Smith, J.G., Ratte, J.C., and Leeman, W.P., 1984, 

Shield volcanoes in the Wrangell Mountains, Alaska, in: The 

United States Geological Survey in Alaska: Accomplishments during 1982: U.S. Geological Survey Circular 939, p. 

71-75.

Richter, D.H., Rosenkrans, D.S., and Steigerwald, M.J., 1995, 

Guide to the Volcanoes of the Western Wrangell Mountains, 

Alaska Wrangell-St. Elias National Park and Preserve: 

U.S. Geological Survey Bulletin, 2072, 31 p.

Riehle, J.R., Kienle, Juergen, andEmmel, K.S., 1981, Lahars in 

Crescent River valley, lower Cook Inlet, Alaska: Alaska 

Division of Geological and Geophysical Surveys Geologic 

Report, 53, 10 p.

Riehle, J.R., 1985, A reconnaissance of the major Holocene 

tephra deposits in the upper Cook Inlet region, Alaska: 

Journal of Volcanology and Geothermal Research, v. 26, p. 

37-74.

Riehle, J.R., and Detterman, R.L., 1993, Quaternary geologic 

map of the Katmai quadrangle and adjacent parts of the 

Naknek and Atognak quadrangles, Alaska: USGS Misc. Inv. 

Map 1-2032, 1:250,000.

Robinson, G.D., 1948, Exploring Aleutian volcanoes: National 

Geographic Magazine, v. 94, p. 509-528.

Romick, J. D., Perfit, M.R., Swanson, S.E., and Shuster, R.D., 

1990, Magmatism in the eastern Aleutian Arc: temporal 

characteristic of igneous activity on Akutan Island: 

Contributions to Mineralogy and Petrology, v. 104, p. 700- 

721.

Rose, W.I., Kostinski, A.B., and Kelley, Lee, 1995, Real time Cband radar observations of 1992 eruption clouds from Crater 

Peak, Mount Spurr volcano, Alaska. In T.E.C. Keith 

(Editor), The 1992 eruptions of Crater Peak vent, Mount 

Spurr volcano, Alaska: U.S. Geological Survey Bulletin 

2139, p. 19-26.

Sapper, Karl, 1927, Vulkankunde: J. Engelhoras Nachf. Stuttgart, 

p. 338-343.

Scholl, D.W, Greene, R.G., andMarlow, M.S., 1970, Eocene age 

of the Adak Taleozoic(?)' rocks, Aleutian Islands, Alaska: 

Geological Society America Bulletin, v. 81, p. 3583-3592.

Self, S., Kienle, J., and Huot, J.P., 1980, Ukinrek Maars, Alaska, 

II. Deposits and formations of the 1977 craters: Journal of 

Volcanology and Geothermal Research, v. 7, p. 39-65.

Sekora, P., 1973, Aleutian Island National Wildlife Refuge

wilderness report; preliminary draft: U.S. Fish and Wildlife 

Service, 409 p.

Seward Weekly Gateway, March 14, 1908.

Siebert, L., Glicken, H., and Kienle, J., 1989, Debris avalanches 

and lateral blasts at Mount St. Augustine volcano: Alaska: 

National Geographic Research, v. 5, p. 232-249.

Simons, F.S., and Mathewson, D.E., 1955, Geology of Great 

Sitkin Island, Alaska: U.S. Geological Survey Bulletin 

1028-B, p. 21-43.

Simkin, T., Siebert, L., McClelland, L., Bridge, D., Newhall, C., 

Latter, J. H., 1981, Volcanoes of the World: Stroudsberg, 

Pennsylvania, Hutchinson Ross, 232 p.

Simkin, T. and Siebert, L., 1994, Volcanoes of the World, 2nd 

Edition: Geoscience Press, Inc., Tucson, Arizona, 349 p.

Singer, B.S., Myers, J.D., and Frost, C.D., 1992, Mid-Pleistocene 

lavas from the Sequam volcano center, central Aleutian aarc: 

closed-system fractional crystallization of a basalt to 

rhyodacite eruptive suite: Contributions to Mineralogy and 

Petrology, v. 110, p. 87-112.

Smith, W.R., 1925, Aniakchak Crater, Alaska Peninsula: U.S. 

Geological Survey Professional Paper 132-J, p. 139-149.

Smithsonian Institution, 1969, Center for Short-Lived Phenomena, Report of 17 September 1969: Cambridge, Massachusetts.

103
CATALOG OF THE HISTORICALLY ACTIVE VOLCANOES OF ALASKA -

Smithsonian Institution, 1976, Scientific Event Alert Network

Bulletin, v. 1, nos. 1, 3-4, 6-11, 13-14. 

Smithsonian Institution, 1977, Scientific Event Alert Network

Bulletin, v. 2, nos. 1,2-5. 

Smithsonian Institution, 1978, Scientific Event Alert Network

Bulletin, v. 3, nos. 1, 2, 5, 9, 10. 

Smithsonian Institution, 1979, Scientific Event Alert Network

Bulletin, v. 4, no. 2. 

Smithsonian Institution, 1980, Scientific Event Alert Network

Bulletin, v. 5, nos. 7, 8, 9, 11. 

Smithsonian Institution, 1981, Scientific Event Alert Network

Bulletin, v. 6, no. 9. 

Smithsonian Institution, 1982, Scientific Event Alert Network

Bulletin, v. 7, no. 2. 

Smithsonian Institution, 1983, Scientific Event Alert Network

Bulletin, v. 8, nos. 8,10-12. 

Smithsonian Institution, 1984, Scientific Event Alert Network

Bulletin, v. 9, nos. 1, 3. 

Smithsonian Institution, 1985, Scientific Event Alert Network

Bulletin v. 10, no. 12. 

Smithsonian Institution, 1986, Scientific Event Alert Network

Bulletin, v. 11, nos. 3-8, 9-12. 

Smithsonian Institution, 1987, Scientific Event Alert Network

Bulletin, v. 12, nos. 1-4, 6-12. 

Smithsonian Institution, 1988, Scientific Event Alert Network

Bulletin, v. 13, nos. 2, 4-8. 

Smithsonian Institution, 1989, Scientific Event Alert Network

Bulletin, v. 14, nos. 4, 11-12. 

Smithsonian Institution, 1990, Bulletin of the Global Volcanism

Network, v. 15, nos. 1-7, 9-12. 

Smithsonian Institution, 1991, Bulletin of the Global Volcanism

Network, v. 16, no. 1, 11-12. 

Smithsonian Institution, 1992, Bulletin of the Global Volcanism

Network, v. 17, nos. 1, 3-7, 11-12. 

Smithsonian Institution, 1993, Bulletin of the Global Volcanism

Network, v. 18, nos. 1-2, 7-12. 

Snyder, G.L., 1954, Eruption of Trident Volcano Katmai National

Monument, Alaska, February-June 1953: U.S. Geological

Survey Circular, 318, 7 p. 

Snyder, G.L., 1959, Geology of Little Sitkin Island, Alaska: U.S.

Geological Survey Bulletin, 1028-H, p. 169-210. 

Sturm, Matthew, Benson, Carl, and MacKeith, Peter, 1986,

Effects of the 1966-1968 eruptions of Mount Redoubt on the

flow of Drift Glacier: Journal of Glaciology, v. 32, no. 12, p.

355-362. 

Till, A.B., Yount, M.E., and Riehle, J.R., 1993, Redoubt Volcano,

southern Alaska: A hazard assessment based on eruptive

activity through 1968: U.S. Geological Survey Bulletin

1996, 19 p. 

Till, A.B., Yount, M.E., and Bevier, M.L., 1994, The geologic

history of Redoubt volcano, Alaska. In T.P. Miller and B.A.

Chouet (Editors), The 1989-90 eruptions of Redoubt

volcano, Alaska: Journal of Volcanology and Geothermal

Research, v. 62, nos. 1-4, p. 11-30. 

Tuck, B. H., Huskey, Lee, and Talbot, Liz., 1992, The economic

consequences of the 1989-90 Mt. Redoubt eruptions:

Institute of Social and Economic Research, University of

Alaska Anchorage, unpublished report, 42 p. 

Turner, D.L., and Nye, C.J., 1986, Geochemistry of eruptive

events at Mt. Spurr, Alaska, in Turner, D.L., and Wescott,

E.M., eds., Geothermal energy resource investigations at

Mt. Spurr, Alaska: University of Alaska Fairbanks, Geophysical Institute Report, UAG R-308, p. 2-1 to 2-7.

U.S. Coast and Geodetic Survey, 1947, United States Coast Pilot, 

Alaska: Pt. 2, Yakutat Bay to Arctic Ocean, 5th edition 

[1948], 659 p.

Veniaminov, Ivan, 1840, Zapiski ob ostrovkh Unalashkinskago 

otdela [Notes on the islands of the Unalashka District], St. 

Petersburg, translated by Black, L.T., and Geoghegan, R.H., 

1984, Kingston, Ontario, Canada, 513 p.

Waitt, R.B., Mastin, L.G., and Miller, T.P., 1995, Ballistic 

showers during Crater Peak eruptions of Mount Spunvolcano, summer 1992. In T.E.C. Keith (Editor), The 1992 

eruptions of Crater Peak vent, Mount Spurr volcano, Alaska: 

U.S. Geological Survey Bulletin 2139, p. 89- 

106.Wentworth, C.K., 1951, The Volcano Letter, no. 514, 6

PWilcox, R.E., 1959, Some effects of recent volcanic ash falls 

with especial reference to Alaska: U.S. Geological Survey 

Bulletin, 1028-N, p. 409-476.

Wilson, C.R., andForbes, R.B., 1969, Infrasonic waves from 

Alaskan volcanic eruptions: Journal and Geophysical 

Research, v. 74, p. 4511-4522.

Yount, M.E., Miller, T.P, and Gamble, B.M., 1987, The 1986 

eruptions of Augustine Volcano, Alaska: Hazards and 

effects, in Hamilton, T.D., and Galloway, J.P, eds., Geologic 

studies in Alaska by the U.S. Geological Survey during 

1986: U.S. Geological Survey Circular 998, p. 4-13.

Yount, M.E., Miller, T.P, Emanuel, R.P, and Wilson, F.H., 1985, 

Eruption in an ice-filled caldera, Mount Veniaminof, Alaska 

Peninsula, in Bartch-Winkler, Susan, and Reed, K.M., eds., 

The United States Geological Survey in Alaska, Accomplishments during 1983: U.S. Geological Survey Circular 

945, p. 58-60.

Yount, M.E., and Miller, T.P, 1987, Hazards implications of the 

1983-84 eruption of Mt. Veniaminof, Alaska (abs.): 

Symposium Agenda and Abstracts, 1987 Geologic Hazards 

Symposium, Alaska Geological Society, Anchorage, Alaska.

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