GEOLOGICAL SURVEY CIRCULAR 318

ERUPTION OF TRIDENT VOLCANO 

KATMAI NATIONAL MONUMENT, ALASKA 

FEBRUARY-JUNE, 1953

UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 318

ERUPTION OF TRIDENT VOLCANO KATMAI NATIONAL MONUMENT, ALASKA

FEBRUARY-JUNE, 1953

By George L. Snyder

Washington, D. C., 1954

Free on application to the Geological Survey, Washington 25, D. C.

ERUPTION OF TRIDENT VOLCANO KATMAI NATIONAL MONUMENT, ALASKA

FEBRUARY-JUNE, 1953

By George L. Snyder

CONTENTS 

Page

Abstract...................................... 1

Introduction................................... 1

Chronology of the eruption of Trident Volcano .... 3

Page

Volume of material erupted..................... 6

Current and recent activity of other vents........ 7

References cited .............................. 7

ILLUSTRATIONS

Page

Figure 1. Location map of Trident Volcano in Katmai National Monument, Alaska ........................... 2

2. Sketch map of lava flow from Trident Volcano, February-June, 1953 ............................. 5

TABLE

Table 1. Estimated dimensions of lava flow from Trident Volcano

Page

ABSTRACT

Trident Volcano, one of several "extinct" 

volcanoes in Katmai National Monument, erupted 

on February 15, 1953. Observers in a U. S. Navy 

plane, 50 miles away, and in King Salmon, 

75 miles away, reported an initial column of 

smoke that rose to an estimated 30, 000 feet. Thick 

smoke and fog on the succeeding 2 days prevented 

observers from identifying the erupting volcano or 

assessing the severity of the eruption. It is 

almost certain, however, that during the latter 

part of this foggy period, either Mount Martin or 

Mount Mageik, or both, were also erupting sizable 

ash clouds nearby. The first close aerial observations were made in clear weather on February 18. 

At this time a thick, blocky lava flow was seen 

issuing slowly from a new vent at an altitude of 

3,600 feet on the southwest flank of Trident 

Volcano. Other volcanic orifices in the area were 

only steaming mildly on this and succeeding days. 

Observations made in the following weeks from 

Naval aircraft patrolling the area indicated that 

both gas and ash evolution and lava extrusion 

from the Trident vent were continuing without 

major interruption. By March 11 an estimated 

80-160 million cubic yards of rock material had 

been extruded. Air photographs taken in April and 

June show that the extrusion of lava had continued 

intermittently and, by June 17, the volume of the 

pile was perhaps 300-400 million cubic yards of 

rock material. Ash eruptions also apparently 

occurred sporadically during this period, the last 

significant surge taking place June 30. No civilian 

or military installations have been endangered by 

this eruption at the date of writing.

INTRODUCTION

The following text is a preliminary report of the 

eruption of Trident Volcano in Katami National Monument 

(fig. 1). Most of the information, including a sizable film 

library, was obtained by personal observations during 

flights of U. S. Navy planes. Supplementary information 

was obtained secondhand from observers in the U. S. Air 

Force, U. S. Coast Guard, and commercial planes. The 

continued cooperation of all branches of the U. S. Navy 

made possible the successful observation of this eruption 

by the writer and other observers. Particular appreciation is due Rear Admiral John Perry, USN, Commandant of the 17th Naval District with headquarters at 

Kodiak, and Captain W. K. Rhodes, USN, Commanding 

Officer, U. S. Naval Station, Kodiak, for authorizing 

the use of the Navy facilities and equipment under their 

commands which were required for the operation.

Personal acknowledgments are also extended to 

the following people: Capt. Russell J. Bellerby, Chief 

of Staff, Com 17; Comdr. W. G. von Bracht, Air 

Operations Officer, Com 17; Lt. Comdr. J. S. Paretsky, 

Flight Officer, Kodiak; all the pilots of the Navy planes 

that patrolled the Trident and Iliamna areas, including 

Lt. Comdr. George H. G. Webster, Lt. Dee L. Leland, 

Lt. James Ingram, Lt. Comdr. Richard Larsen, 

Lt. Mark J. Hessy, Lt. H. G. Silliman, Lt. Robert L. 

Neth, Lt. (jg.) Robert L. Boiling, Lt. (jg.) R. J. Henning, 

and P. N. Cedercrans ADC/AP; Lt. Frank O. Brink, 

Acting Public Information Officer, 17th Naval District 

Headquarters, Kodiak; Lt. Comdr. Tom Herbert, 

Radio/TV Officer, 13th Naval District Public Information Office; Lt. Lawrence Barrett, Pictorial Officer, 

13th Naval District Public Information Office; 

Lt. Comdr. Glen Thompson, U. S. Coast Guard unit,
NATIONAL MONUMENT M

Kaguyak 

village

Knife Peak Volcano

Mount Martin x

Cape Kubugokli . \,

PACIFIC OCEAN

Figure 1. Location map of Trident Volcano in Katmai National Monument, Alaska.

2
Kodiak; all the Navy photographers including Michael J. 

O'Grady, Jr., AF-3; Samuel E. Bennett, AF-3; 

James C. Toon, AF-3; Henry A. Geary, AF-3; Dave 

Berg, AF; William W. Henderson, AF; William T. 

Edgar, AF; Curtis E. Von Kaenel, AF; and Marvin R. 

Soper, AF; Gene Vosburg, Jr., JO-3; Miss Anastasia 

Trasko, Secretary to the Chief of Staff, Kodiak; and 

all the many crew members of the Navy planes, and 

other personnel of the Naval Station.

Richard R. McDonald, Seismologist with the 

Geophysical Branch of the U. S. Geological Survey, 

observed the eruptive area during the period from 

February 18 to March 5. The writer's observations 

were made during the period from February 25 to 

March 13 and again on June 17. This report includes 

the observations made by Mr. McDonald, the writer, 

and many others, evaluated by mutual discussion.

CHRONOLOGY .OF THE ERUPTION 

OF TRIDENT VOLCANO

Lieutenant Commander Frank Chase, flying eastward at 15,000 feet altitude over Port Heiden on the 

Alaskan Peninsula one calm Sunday afternoon was 

a.stonished to see a huge tower of smoke mushroom into 

the sky on the horizon almost 150 miles away. The 

time was about 4:00 p.m. (A.s.t.), February 15, 1953. 

The center of activity was determined to be somewhere 

in the vicinity of Mount Katmai in Katmai National 

Monument. The eruption cloud was estimated at the 

time to extend to about 30,000 feet, twice the altitude 

at which the plane was flying. A photograph taken by 

a crew member of Commander Chase's plane from just 

south of Cape Kekurnoi (35 miles south-southwest of 

Katmai) corroborates this estimate. Only 1 eruption 

cloud is visible in this photograph and, although the 

picture is not clear enough for positive identification, 

subsequent observations indicated that this smoke 

column was arising from Trident Volcano, an old 

eroded volcano with no previous historical record of 

eruption, located 4 miles west-southwest of Mount 

Katmai.

The initial explosion was also reported by the 

office of Northern Consolidated Airlines in King Salmon 

(on the north side of the Alaskan Peninsula) about 

75 miles northwest of the eruption. An Associated 

Press release of February 15 states that "a unidentified 

Air Force pilot flying over the area 50 minutes after 

the eruption saw smoke and cinders had shot into the 

air to a height of 30, 000 feet. " Because of an unfavorable location behind mountains no one in Kodiak village 

or on Kodiak Naval Station (100 miles southeast of the 

eruption) could observe the initial smoke column.

When Mr. Chase landed at Kodiak Naval Station 

he reported his observations to Rear Admiral John 

Perry, Commander Alaskan Sea Frontier and Commandant 

17th Naval District. Admiral Perry ordered Navy patrol 

planes to maintain surveillance on the volcano in event 

of increased activity that might endanger the lives of 

civilian and military personnel on the Alaska Peninsula 

and Kodiak Island. That same evening, Sunday, 

February 15, one Navy plane was dispatched to the 

scene of the eruption. By then, however, fog and smoke 

had covered the area, and nothing could be seen. Early 

Monday morning, February 16, two Navy planes returned 

to Katmai National Monument. Frank O. Brink was in

charge of the photo crew in one of these planes piloted 

by Lt. Comdr. George H. Webster.. The following Navy 

dispatch describes the first flight: "***Took off at dawn 

700 AM. While enroute noticed thick smoke layer to 

left stretching over 100 miles. Valleys and mountains 

far as eye could see covered with ash. Difficult to 

pinpoint volcano because of cloud layer***LCDR 

Webster said too dangerous to get closer thaja 

25 miles***840 AM Alaska standard time a navy 

crew of Grumman Albatross from the Naval Station 

Kodiak sighted second eruption volcano in Katmai region 

Alaska Peninsula***Huge ball cloud seen 20 degrees 

and 25 miles left of plane's heading. Cloud rose above 

7, 000 ft cloud layer with tremendous spread. Like 

giant mushroom just let go as plane arrived in area. 

Perfect imitation atom bomb explosion. 850 AM cloud 

mushroomed to 30,000 feet. Top fanned out diameter 

10 miles. 855 AM top spread like sunflower to diameter 

25 miles at height of 35,000 feet. " In later conversations, Mr. Brink declared that this eruption cloud 

was light gray and, hence, presumably was a. steam 

explosion that carried but little ash. Movies indicate 

that above the clouds there was only a single mushroom 

smoke cloud, light gray in color.

At about the same timeLt. Comdr. Glen Thompson 

of the U. S. Coast Guard was also patrolling the area 

in a Coast Guard amphibian plane. Mr. Thompson was 

considerably lower than the U. S. Navy planes and also 

closer to the erupting vents. He flew beneath the cloud 

layer that obscured the ground from the higher planes, 

and taking a bearing on Mount Martin, flew northeast 

parallel to the chain of mountains. Near Mageik 

volcano the air became so smoky that he was obliged 

to continue ahead on instruments and did not relocate 

his position until he saw the emerald-green waters of 

the crater lake on Katmai volcano below him. As the 

smoke seemed to be thickest in the vicinity of Knife 

Peak Volcano, Mr. Thompson presumed this to be the 

erupting volcano. The identification of the eruptive 

center as Knife Peak was definitely mistaken, but the 

knowledge that there was thick smoke in the TridentMount Mageik area and none in the Katmai and Mount 

Martin areas was valuable information about the volcanic 

activity at that time. Movies, taken by a crew member 

on this run, show many scenes of smoke, fog, and 

steam, but the only land feature that can be definitely 

identified 'is Mount Martin, with its usual steam plume 

500 feet high.

A summarizing Navy dispatch contains the following 

statement: "Observers on the second plane to visit the 

area Monday [February 16] reported that a second 

column of smoke and possibly a third was seen rising 

approximately 10 miles southwest of Katmai Volcano. " 

This observation, if correct, would imply that both 

Trident and Mount Martin were erupting. Perhaps 

"steam" is meant instead of smoke, however, in which 

case the situation at the craters of Mageik and Mount 

Martin would be normal. No still pictures of the 

activity on February 16 are available.

Part of a Navy dispatch describing the observations 

of a flight on Tuesday (February 17) reads as follows: 

"Navy patrol crew from NAVSTA Kodiak today witnessed 

mass eruption of Katmai National Park. This was 

third and most spectacular display. 1055 AST plane 

flying 8000 ft. on 270 degrees course over Shelikof 

Strait sighted large black ball smoke about 25 miles 

10 degrees left plane's heading. It rolled up like smoke
from oil fire to 15, 000 feet. Plane circled left of the 

eruption. In two minutes second cloud boiled up 

8 miles NE first one. Moved closer, black smoke rose 

30, 000 feet. Streams of ash poured out of black smoke 

like rain falling from thunder cloud***smoke and debris 

from volcanoes appeared to move slowly to NW. Continued to fly within 5 to 6 miles of the erupting area. 

Smoke spread until it was difficult to see separate 

columns. 1 Smell of sulphurous volcanic smoke strong 

in plane. Pilot [ Lt. James T. Ingram] pulled plane 

further away fearing ash might damage props and engine. 

Through an occasional break in the 8000 ft cloud layer 

below could see mountains and valleys covered with 

gray black ash." This much of this dispatch is well 

attested by the still photographs taken by Navy photographers as well as by Lieutenant Brink's 16 millimeter 

motion pictures of this phase of the eruption. It appears 

certain that there were at least 2 vents, Trident and 

1 other, which were erupting smoke and ash on the 

third day of the activity. The identity of the other vent 

is not certain. Principal possibilities are Mount Martin 

and Mageik because these 2 volcanoes are almost continuous "steamers. "

One Navy photograph, dated February 17 and 

showing 2 smoke columns projecting above an undercast cloud layer, is labeled: "Two erupting clouds of 

steam and ash from Mount Katmai, in the foreground, 

and Mount Mageik, eight miles from Katmai***. " If 

the estimate of an 8 mile distance between the columns 

is correct, the 2 erupting volcanoes must have been 

Trident and Mount Martin rather than Katmai and 

Mount Mageik. However, another photograph, also 

dated February 17 and supposedly taken on the same 

flight, shows Mount Martin placidly steaming as usual. 

The ash that fell from these 2 eruptions on February 17 

was buried completely under fresh snow, so that the 

excellent observations-from the air on February 18 contribute nothing to identify the second erupting volcano. 

It must have been either Mount Martin or Mount Mageik.

.On Wednesday, February 18, the weather cleared 

making possible photographs and direct observations 

from the air by Navy patrols. Ash and steam were 

being erupted as a gray column from a vent at an altitude of about 3, 600 feet in an amphitheater on the southwest flank of Trident Volcano, and a blocky lava flow 

from this vent had spread over an area about 700 feet 

wide and 800 feet long (see fig. 2). Copious steam was 

being emitted from the area immediately adjacent on 

the uphill side of the active vent. The lava flow, 

apparently very slow moving and viscous, showed a 

surface of large blocks of lava formed as the stiffening 

material reached the lava surface. Earlier news dispatches had mentioned "long streams of molten lava" 

flowing down the mountain side but these must have 

been merely mudflows composed of meltwater and ash. 

A thin blanket of ash covered the area downwind (west) 

of the vent, lying on new snow which had concealed the 

ash deposits of previous days. No observations were

1 The Navy dispatch of February 17 also contains the following statements: "1115 AST one after another new columns of smoke shot up in a line 

just like a chain of explosions. Ash started hitting plane *** more explosions took place in different areas. Counted between 6 and 8 separate columns of smoke." These statements require some clarification. From later 

conversations with Lieutenant Brink and the other observers and after seeing Brink's film it appears that all of the above could have been caused by 

1 vent sending separate puffs up through £ cloud layer into a zone of moderate winds. Also, it might have been said that the plane started hitting ash 

rather than the above, as any ash at that altitude probably would have lost 

the original propulsive force of the gaseous explosion.

made of the ash distribution around the neighboring 

volcanoes, so the uncertainty about the February 17 

eruptions still remains.

On the next flight, February 21, the ash column 

was again gray and steam-laden, with copious steam 

also being emitted from the area on the uphill side, as 

on February 18, and the lava had advanced about half 

a mile southward down slope. If the rate of advance 

of the flow front can be taken as a reliable indication, 

it was during the period from February 18 to 21 that 

the lava rock was extruded most rapidly. On the flight 

of February 27 the eruptive column was light gray, and 

much steam came from the hot area on the uphill side 

of the vent. The lava front had extended several 

hundred feet further down slope. On March 4, low 

clouds obscured the vent, and a slight widening of the 

lava flow on the eastern side of the toe was all that 

could be seen. This eastern lobe, which was active 

until March 9 and which became reactivated in the late 

Spring, was a "squeeze-under, " that is, the lava 

forming the lobe was forced beneath the frozen eastern 

margin of the flow. From March 4 to March 11 the 

flow, especially in the central portions, expanded like 

a balloon from internal additions. Then, from March 9 

until the observation on March 11, further overflow 

from the vent had produced a northwest lobe. The ash 

puffs were progressively less frequent on each of the 

observations in early March, and the eruptive column 

on March 11 was very unsteady in the wind between 

bursts.

Except for reports of noticeably greater explosive 

activity on March 24, no further observations were 

made until April 6. Navy air photographs taken on 

April 6 indicate that the lava pile had bulged on the east 

and west flanks and increased in height in the vent area. 

Photographs on June 2 show further growth of the lava 

mound on the east flank and a landslide formed by 

slumping of a portion of the southeastern toe. Minor 

ash apparently had been deposited over the flow sometime after April 6, and this surface had been partly 

overridden by new lava. By June 17 no further landsliding of consequence had occurred although a 

crevasse near the lip had widened appreciably. New 

lava was exuding slowly from the vent, which it 

buried completely, and was piling up at the source 

as well as spreading down the northwest, west, and 

northeast flanks. Steam with very little ash rose 

from the apex of the pile, from the northwest edge 

of the new lava, and, as had been normal since 

February 18, from the area at the northeast base 

of the pile. Concentric slump cracks were noticed 

in the latter area (see fig. 2).

In the evening of June 30, according to messages from the Navy at Kodiak, a fishing vessel 

reported ash in the air and pea-size pumice floating 

in Shelikof Strait from Cape Kuliuk, Kodiak Island, 

for a distance of 25 miles southwest. A patrol 

plane reported an ash column at Trident Volcano 

rising from a glowing vent and a. fair amount of ash 

blanketing the area south of Katmai. Visibility was 

poor southeast of Trident as far as Kodiak Island, 

because of dust in the air. It is not certain whether 

the pumice in Shelikof Strait was newly erupted 

from Trident Volcano, however. It may have been 

derived from much older pumice deposits on Kodiak 

or the Alaskan Peninsula.
Southeast fumarole, 1953

Figure 2. Sketch map of lava flow from Trident Volcano, February-June, 1953.

5
VOLUME OF MATERIAL ERUPTED

The writer has estimated that 80-160 million 

cubic yards of lava and ash were extruded from the 

Trident vent by March 11, 1953. The volume of the 

volcanic pile during the writer's last observation on 

June 17, 1953, is estimated to have been 300-400 million cubic yards. The rate of emission was never 

constant, and actual ground measurements were not 

taken so that these estimates are to be regarded as 

orders of magnitude only.

The gases and finely comminuted ash of the fume 

cloud escaped from the joint openings over an area of 

5-7 a.cres. The smoke column on February 18 rose 

over a mile into the air. With later observations in 

February and early March the height of this smoke 

column was always 1-2 miles in height, averaging perhaps 1-g- miles. Notable maxima were observed on 

March 9, March 24, and June 30. Before March 11 the 

explosions forming the cloud occurred often enough 

(several to several dozen per minute) so that the column 

was always present. On March 11, however, the explosions were more sporadic, occurring 1-3 minutes 

apart, so that between bursts the smoke from the 

previous explosion would mostly drift away. From the 

later photographs moderate and, infrequently, explosive 

emission of steam with but little ash seems to have 

continued infrequently into June.

Before February 27, all observations of the eruption cloud indicated that it was moving southwest, 

northwest, west, or north before the prevailing winds. 

Observations of ash-covered ground as far away as the 

Bay of Islands, Naknek Lake are reported. Shortly 

before February 27 a snowstorm blanketed the entire 

Katmai National Monument area with clean snow. After 

this time all observations of the eruption cloud showed 

it to be drifting to the south, southeast, east, or northeast, and all fresh deposits of ash atop the new snow 

occurred in these areas within a 20-mile radius of the 

vent. _ Thus, although single observations made between 

February 15 and March 11 would seem to indicate a 

preferential deposition of the ash, actually the wind 

conditions had varied enough during this time to almost 

completely box the compass. It is very difficult to 

estimate the depth of the blanketing ash from a plane. 

Locally "drifts" of the ash from Trident Volcano, 

especially near the vent, may have been a foot to 

several feet in thickness. Probably within a radius 

of 15 miles of the vent an "average" thickness of the 

whole ash deposit would fall within the limits 0.01-0.1 foot. 

A cylinder of this radius and altitude would have a

volume of 7 to 70 million cubic yards. Inasmuch as 

the area actually occupied by the ash is not flat"-but 

very mountainous these figures are probably conservative estimates.

A United Press release of February 26 reports 

that Charles L. Baker of the University of South Dakota 

analyzed samples of a dust deposit tha.t covered portions of the State on February 19 and found them to be 

volcanic ash. He said, the article continues, that 

apparently the ash was the residue of recent volcanic 

eruptions in Alaska, carried there by strong winds. 

If this is true, the ash, if from the Trident vent, must 

have been derived from the initially violent explosions 

of February 15, 16, and (or) 17. These were the only 

eruption clouds which could have transported a very 

fine ash to a stratospheric wind zone. The aerial 

observations indicate that in this case, however, the 

amount of the ash transported beyond a 15-20 mile 

radius can be regarded as negligible from the viewpoint of total volume determination.

The accompanying table gives the estimated 

maximum and average dimensions of the Trident 

lava, flow at different dates. These estimates were 

derived by measuring plotted outlines and cross 

sections of the flow which were drawn to scale on 

a. "blow-up" of the contour map of the area. Both 

the small scale of the original ma.p and the estimated 

position of the flow borders render these figures 

approximations at best.

The volume of lava extruded as of March 11, 1953, 

has been computed as 70-90 million cubic yards. 

Together with the estimate of the amount of ash blown 

out this would make a total volume of 80-160 million 

cubic yards (or 0. 015-0. 029 cubic mile) as a.n order 

of magnitude. By June 17, 1953, it is estimated that 

the volume of the volcanic pile had risen to 300-400 million cubic yards (or 0. 055-0. 073 cubic mile). Note 

that these figures do not take the porosity of the deposits 

or the internal porosity of the actual rock fragments 

into account. It is believed that the error possible in 

the simple estimates makes further refinements 

pointless. For comparison the amount of ash and 

pumice which filled the Valley of Ten Thousand Smokes 

in the great eruption cf 1912 has been estimated to be 

about 1-1^ cubic miles and the volume of the pyroclastic 

material derived from the entire Katmai eruption in 

1912 has been estimated at 6-7 cubic miles (Griggs, 

p. 29,- 31). From this comparison it is easily seen 

that Trident's eruption is but a small puff compared 

to those of the neighboring vents.

Table 1. Estimated dimensions of lava flow from Trident Volcano, in feet

Date 

(1953)

Feb.

Mar.

Apr. 

June

n c_ ___________

18 _________ _ ____ _ _ __ __ _ _ _ _

21 _ --- _ _ _ _ __ _ _ _ __ _____ _ _ _

07 _____ _ _ __

4__ _ _ ____ _ _

q _ _ _ _ _ _ _ _ _ _ ___

H_ ____ ___ _ _ _ _ __ _

6_ _ _ _ _ ___ _

p_ __ __ _ _ _ __

17 _ _ _

Thickness

Maximum

0 

200 

200 

200 

300? 

400- 450 

550- 650 

700- 750 

750- 800 

950-1050

Average

0 

150 

175 

175 

200? 

250-300 

300-350 

400-450 

450-500 

600-700

Width x length

Maximum

Ox 0 

700 x 800 

2000 x 3200 

2500 x 4600 

2600 x 4600 

2800 x 4600 

3200 x 4600 

3800 x 4800 

4100 x 4800 

4400 x 5000

Average

Ox 0 

600 x 700 

1500 x 2800 

1800 x 4000 

1800 x 4000 

1900 x 4000 

2000 x 4000 

2800 x 4000 

3100 x 4100 

3300 x 4300
CURRENT AND RECENT ACTIVITY OF 

OTHER VENTS

Coincident activity of other vents during this 

eruption includes the February 17 ash explosions of 

Mount Martin or Mount Mageik or both and the southeast Trident fumarole mentioned above.

The Anchorage News of March 3 quotes a 

Mrs. William Tauscher of Anchor Point (Kenai 

Peninsula) as saying that Iliamna Volcano "poured 

forth with a huge mushroom-shaped billow of inky black 

smoke at 7:30 a. m. Sunday (March 1). " Two distinct 

sources of eruption are claimed to have been sighted, 

one on top and one off to the side of the mountain. 

Lt. James Ingram USN flying about 50-75 miles southsoutheast of the Iliamna area on March 3 gives a partial 

confirmation of this story. He sighted a cloud column 

rising from the mountain but at that distance could not 

discern whether it was smoke or steam. The writer 

visited the Iliamna area aboard naval aircraft on 

March 5 and 6. On these dates only a small fumarole 

near the top and on the east side of Iliamna was active, 

sending up a column of steam several hundred feet 

high. No ash was visible on the glaciers blanketing 

the mountain.

On March 2 Richard McDonald, U. S. Geological 

Survey seismologist stationed at Adak, rode a Navy 

plane from Kodiak to Adak and back. He reported 

steam rising from Pavlof, Shishaldin, Makushin, and a 

small cone within Okmok Caldera on this day. Probably 

other volcanoes elsewhere along the chain were also 

steaming. This is the normal condition throughout the 

tectonically and volcanically active Aleutian arc and 

should not be interpreted as a reaction related to the 

Trident eruption. The explosions of Mount Martin or 

Mount Mageik on February 17 (and, possibly the late 

afternoon of February 16) appear to have been related 

to the Trident eruption.

Lt. Dee L. Leland, USN, who has probably 

observed as much of the early phases of the Trident 

eruption as anyone, reported that on the flight on 

March 11 he noticed a marked coincidence in timing 

of the Trident explosions with the much smaller steam 

puffs from Mageik crater. Whether Lt. Leland was 

observing coincidental activity or connected events of 

genetic significance is not known.

Since February 17 both Mount Martin and Mount 

Mageik have shown no more activity than their normal 

puffing of steam. Other fumarolic areas in the Katmai 

National Monument that are now active include the 

"hotspot" on the southeast flank of Trident, Katmai

crater (its lake, though locally containing rafts of ice, 

was unfrozen while, nearby, the unnamed crater lake 

adjacent to Kaguyak Bay was frozen over), a line of 

large fumaroles and "hot" ground extending along the 

bench below the west side of Baked Mountain for about 

2 miles (these were observed by Emil Meitzner, U. S. 

Geological Survey, from the middle Valley of Ten 

Thousand Smokes in June 1952), a large area of small 

fumaroles and hot ground from Novarupta to Broken 

Mountain, a few mud-pots along the "Greased Ridge" 

between Baked and Broken Mountains, a single large 

fumarole in the canyon of the River Lethe at the north 

end of the Buttress Range near the Three Forks area, 

and, possibly, a small "hotspot" (no steam noticed) 

within the inner crater ring of Knife Peak. A large 

fumarole, reportedly by (1952) on the northwest slope 

of Katmai, could not be seen. As far as can be determined it is likely that all but the southeast Trident 

fumarole were active before and have continued unchanged throughout the Trident eruption. Probably 

other small fumaroles exist, especially in the upper 

Valley of Ten Thousand Smokes, but were not noticed 

from the plane.

The recorded eruptive history of the Katmai 

National Monument area begins with the eruption on 

June 1912 that formed the Valley of Ten Thousand 

Smokes, eviscerated Mount Katmai, and deposited 

over a foot of ash on parts of Kodiak Island. This 

is without doubt the largest recorded Aleutian-Alaskan 

eruption although several other recorded eruptions 

in other parts of the world were more violent, more 

destructive, or erupted greater quantities of rock 

material. Furthermore geologic evidence indicates 

that many other eruptions of greater magnitude than 

the Katmai disturbance in 1912 have occurred during 

prehistoric times throughout the Aleutian island arc. 

Since 1912 Katmai, Mageik, Mount Martin, and Novarupta have been steaming almost constantly and giving 

vent to minor ash eruptions sporadically (Coats,- 

table 2; and personal communication with Howard A. 

Powers, U. S. Geological Survey). Mageik is last 

reported to have erupted in 1951 (Kodiak Mirror, 

Feb. 21, 1953, p. 1). U. S. Air Force aerial photographs taken in July 1951, show a. linear grouping of 

fumaroles on the southwest flank of Trident Volcano 

near the site of the present vent.

REFERENCES CITED

Coats, Robert R., 1950, Volcanic activity in the 

Aleutian arc: U. S. Geol. Survey Bull. 974-B.

Griggs, Robert F., 1922, The Valley of Ten Thousand 

Smokes: Natl. Geog. Soc., p. 29, 31, 98.

INT.-DUP. SEC., HASH., D.C. (2 08I|