LIVING ITH 

VOLCANO S 

THE U.S. GEOLOGICAL SURVEY'S VOLCANO HAZARDS PROGRAM 
Front cover: April 21, 1990, eruption of Redoubt Volcano, Cook Inlet, Alaska, showing layered plume rising into the 

stratosphere. Copyrighted photograph by Joyce Warren. Used with permission. 
LIVING WITH 

VOLCANOES 

The U.S. Geological Survey's Volcano Ha~ards Program 

By 

Thomas L. Wright 

and 

Thomas C. Pierson 

U.S. Geological Survey Circular 1073 
U.S. DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Any use of trade, product, or firm names in this publication is for descriptive 

purposes only and does not imply endorsement by the U.S. Government 

Text and illustrations edited by Carolyn Donlin 

Graphics prepared by Susan Mayfield 

Book design and layout by Fred Garrido and Carolyn Donlin 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1992 

Free on application to the 

Books and Open-File Reports Section 

U.S. Geological Survey 

Federal Center, Box 25425 

Denver, CO 80225 

Library of Congress Cataloging-in-Publication Data 

Wright, Thomas L. (Thomas Llewellyn), 1935-

Living with volcanoes I by Thomas L. Wright and Thomas C. Pierson. 

p. cm.-(U.S. Geological Survey circular ; 1073) 

Includes bibliographical references. 

Supt. of Docs. no.: I 19.4/2: 1073 

1. Volcanic Hazard assessment. 2. Volcanic hazard assessmentUnited States. 3. Volcanological research-United States. 

4. Volcano Hazards Program (US) I. Pierson, Thomas C. 

II. Title. Ill. Series. 

QE527.6.W75 1991 

363.3'495-dc20 91-19826 

CIP 
CONTENTS 

Introduction 

1 

Acknowledgments 

4 

Program goals and activities throughout the 1980's 

6 

Volcano observatories: taking the pulse of active volcanoes 

6 

A volcano's history: key to assessment of hazards 

14 

The challenge of predicting eruptions 

23 

Communicating research results and hazards information 

24 

Meeting the demands for global volcano hazards reduction 

29 

Assistance to developing cou,:1tries 29 

A look toward the future 

33 

Eruption prediction 33 

Volcano hazard assessment 33 

Research in volcano processes 33 

Effective communication 34 

Working in the world laboratory 34 

Epilog 

35 

Photo glossary 

36 

References cited 

42 

Contents Ill 
IV Contents 

TABLES 

1. Notable eruptions of volcanoes in the United States during the 

20th century 5 

2. Facilities and activities of the U.S. Geological Survey Volcano 

Hazards Program 7 

3. Collaborative work with the U.S. Geological Survey Volcano 

Hazards Program 9 

APPENDIXES 

1. Active and potentially active volcanoes in the United States 45 

2. Status of hazard evaluation for volcanoes in the United States 49 

3. Tasks for the 1990's and visions for the 21st century 52 

4. Participants in the workshop "Volcano Hazards Program Directions 

for the 1990's" 57 

SPECIAL TOPICS 

Continuous eruption and hazards at Kilauea since 1983 2 

Mount St. Helens reawakens 3 

How scientists study volcanoes 10 

Water, rock, and gravity: a potentially deadly combination at 

volcanoes 18 

Hazard-zone maps and volcanic risk 20 

Predictions, forecasts, and factual statements 24 

Danger in the stratosphere: aircraft and volcanic plumes 27 

Hazard, risk, and acceptable risk 28 

A volcanic disaster averted in the Philippines 31 
Conversion Factors 

For readers who wish to convert measurements from the metric system of 

units to the inch-pound system, the conversion factors are listed below. 

Multiply 

centimeter 

meter 

kilometer 

square kilometer 

square hectometer 

cubic meter 

By 

Length 

0.394 

3.281 

0.621 

Area 

0.386 

2.471 

Volume 

1.308 

To obtain 

inch 

foot 

mile 

square mile 

acre 

cubic yard 

A simple rule of thumb for approximate conversions: 1 inch equals about 

2.5 centimeters; 1 yard equals about 1 meter 

v 
56' 

52' 

40' 

0 

20' 

160' W 

ALASKA 

0 

2000 KILOMETERS 

0~ 

7 

I:) AWAIIAN ~ .... ISLANDS 

Area of C 

D Outline of area shown in larger detail 

64' 

U.S.S.R. 

Kiska"'-. 

BERING SEA 

Akutan 

Bogoslof* 

Okmok 

~ 

i>-

CANADA 

UNITE STATES 

140'W 

. . 

\ 

. . 

\ 

. . ALASKA \ 

. . CANADA 

Wrangell • 

\ 

. . 

\ 

. . 

\ 

PACIFIC OCEAN 

100 200 300 KILOMETERS 

I I I 

A 

64' 

60' 

EXPLANATION 

• Volcano active during 

past 2,000 years 

Population center 

100,000 to 350,000 

Index maps showing locations of active and potentially active volcanoes and nearby population centers (not all labeled) of the United 

States. See Appendix 1 for a summary of volcanic activity at all features shown here, and for complete names, as approved by the U.S. 

Board on Geographic Names . Asterisk denotes informal name. A, Volcanoes of the Alaska Peninsula and Aleutian Islands, Alaska. B, 

Principal Cascade Range volcanoes, conterminous Western United States. C, Volcanoes of the Hawaiian Islands, including the active 

Loihi Seamount. 
22' 

11 5' 110' 

45' 

"' Mount Bake!rr! -T-------------.----

.& Giac· . • • eattie er Peak 1 ( M • WAS Pokane• • . St Hount ..& M f-1 LNG TON I I ·J::etens nt Rainier • ·, • Great Falls '"'I "' O M I , Porr and • ount Adams • •-, MONTANA I 

.... M • I, • • oum Hood J IEXPLANATION I "·~· ...... ·-·--l . • 0 M ' 1..·~ • Billings , ·---

Eugene• ..& .,.. oum Jefferson ,J \ I 

•hree Sist ( IDAHO , r----------·---

A Volcano active during past 

2,000 years 

0 Potentially active volcano 

., 

t:t Area of potential volcanic activity :> 

40' (") 

Population centers "r] 

- • 40,000 to 100,000 (") 

• 100,000 to 350,000 

• 350,000 to 1,000,000 

e Greater than 1 ,000,000 

35' 

~ 

22' 

20 40 60 KILOMETERS 

OAHU 

~ 

"' N ers • ",,....,l'. t:t Yellowstone I 

Crater 0 cewberry I I • Lake rater • Boise 1 1 

0 Craters otO • I WYOMI NG 1 

·--- REGON 1 the Moon • t------

Mount -=------ I Casper • 

Shasta" Mf!dicine L~k; "'------,-·----~ ! 

I I I I 

• "' • I • I I 

Lassen 1 N I ·---r Cheyenne • L Peak 1 E VADA I • Salt Lake ---------- ---~ 

0 Clear La Reno j I City j I • I 

e sacra.:• UTA H e o enver •uento 

. ~ . • • A' Long Valley • 

<; • Caldera 1 COLORADO 

'('~ CosoO ·,,Las Vegas !----------J-------------,-...J 

100 200 

~ '· ..... ) 

. *'~ . ' t ·,i t:t 

"\ San Francisco Field 

i 

I 

ARIZONA 

i, Phoenix. 

• e Aibuquerque 

t:t Bandera Field 

NEW MEXICO 

----;, .. 

....... e Tucson! • I 

·-.. I --------rl ·-.. _____ ...__J____ H 

0 Kohala 

~ 20' 

EXPLANATION 

A Volcano active during past 

2,000 years 

A Kilaue 0 Potentially active volcano 

Population centers 

19' • 50,000 to 1 00,000 

• 350,000 to 1 ,000,000 

c 

LIVING WITH 

VOLCANOES 

The U.S. Geological Survey's Volcano Hazards Program 

INTRODUCTION 

The 1980 cataclysmic eruption of Mount St. Helens (Lipman and 

Mullineaux, 1981) in southwestern Washington ushered in a decade 

marked by more worldwide volcanic disasters and crises than any other 

in recorded history. Volcanoes killed more people (over 28,500) in the 

1980's than during the 78 years following the 1902 eruption of Mont 

Peh~e (Martinique). Not surprisingly, volcanic phenomena and attendant 

hazards received attention from government authorities, the news media, 

and the general public. As part of this enhanced global awareness of volcanic hazards, the U.S. government significantly expanded the Volcano 

Hazards Program of the U.S. Geological Survey (Bailey and others, 1983) 

in response to the eruptions or volcanic unrest during the 1980's at 

Mount St. Helens (Washington), Mauna Loa and Kilauea (Hawaii), Long 

Valley Caldera (Califqrnia), and Redoubt Volcano (Alaska). Entering the 

1990s, the sustained eruptive activity at Kilauea persists unabated, 

Mount St. Helens and Redoubt are still erupting intermittently, and the 

caldera unrest at Long Valley also continues, albeit less energetically 

than during the early 1980's. 

In addition to the areas mentioned above, the U.S. has many other 

active or potentially active volcanoes-over 65, which is more than all 

other countries except for Indonesia and Japan (Simkin and others, 1981; 

Tom Simkin, written commun., 1990). Most of these volcanoes are located 

in Alaska, and 55 of them, including 8 on the U.S. mainland, have shown 

activity since the U.S. was founded, just some 200 years ago. 
CONTINUOUS ERUPTlON AND HAZARDS AT 

KILAUEA SINCE 1983 

Plume of primary 502 -rich gas (vag) rising from Puu Oo vent (upper right) 

and a secondary plume of HCI-rich steam (laze) rising from the entry of lava 

into the ocean (middle left) during the ongoing eruption of Kilauea on 

Hawaii. Photograph by J.D. Griggs. 

Volcanic haze on west coast of the Island of Hawaii carried by tradewinds 

from Kila uea and trapped by an inversion layer on the lee side of Mauna Loa. 

The acid-bearing volcanic pollutants affect crops and water catchment 

systems. Photograph by Dorian Weisel. 

2 Living With Volcanoes 

As of May 1991, the eruption 

on Kilauea's east rift zone that 

began in January 1983 continues 

uninterrupted. Longest lived of 

any rift activity in recorded 

history at any Hawaiian volcano, 

lava flows produced during this 

prolonged eruption have destroyed more than 180 homes and 

obliterated the world-renowned 

black-sand beach at Kaimu, on the 

south coast of the Island of 

Hawaii. Fortunately, no people 

have been killed or injured, but 

more than $5 million in property 

damage and economic loss has 

been incurred to date. In addition 

to hazards from ongoing lava 

flows, the persistent eruption has 

spewed noxious plumes of acidic 

volcanic gases that have affected 

many communities on the island. 

These plumes originate both at 

the erupting vent, producing vog 

(volcanic fog) where sulfur 

dioxide is converted to sulfuric 

acid a short distance downwind, 

and at the ocean, where lava 

entry produces hydrochloric acidbearing laze (lava haze) by 

boiling of seawater. The plumes, 

which also contain particulate 

matter (for example, volcanic 

glass or trace metals), are then 

carried by winds far from their 

source. Both vog and laze obscure 

scenic views, lower agricultural 

yields for certain crops, adversely 

affect people with respiratory or 

heart conditions, and acidify 

rainwater catchment tanks thereby 

producing a secondary hazard of 

leached lead in local wa ter 

supplies. 

The current eruption shows 

no signs of stopping, and the 

continuing hazards pose a serious 

concern throughout the County 

and State of Hawaii, for citizens, 

tourists, and officials alike. 
MOUNT ST. HELENS REAWAKENS 

The first earthquakes struck 

on March 20, 1980. Seismologists 

quickly determined that the 

quakes were centered beneath a 

snowy mountain, known to them, 

but not to the general public, as a 

potentially dangerous volcano, 

which had been dormant for more 

than a century. During the next 

week, the number of earthquakes 

increased, and these quakes 

triggered snow avalanches, which 

in turn forced closure of winter 

recreation areas around the 

mountain. Geologists and geophysicists converged on the scene 

to monitor the activity and met 

with local authorities to alert 

them to the possibility of an 

eruption. On March 27, steam and 

ash exploded from the summit of 

the volcano and marked the 

beginning of several small eruptions during the next two months. 

Public authorities prudently 

closed the area surrounding the 

mountain after being informed of 

the volcano's past violent behavior by those who had conducted 

careful geological studies during 

the preceding 20 years. Although 

closure was a necessary precautionary measure, it created 

discontent and even anger on the 

part of some citizens who wanted 

access to their property and 

recreation sites. Continued 

monitoring of the volcano indicated that its north flank, which 

towered above the most popular 

recreation area, was becoming 

increasingly unstable. Warnings 

were issued for landslides and 

large-scale snow avalanches. 

These warnin gs supported the 

need for continued closure of the 

area, although public pressure 

eventually led to brief, authorized 

forays into the area by cabin 

owners to retrieve belongings. 

One such trip was scheduled for 

the morning of May 18, but it 

never took p lace . 

At 8:32 a .m. on May 18, an 

earthquake triggered a gigantic 

landslide on the unstable north 

flank, which in turn unleashed a 

scorching, explosive blast of hot 

gas laden w ith rock fragments; 

massive floods of mud and rock 

down most river valleys; flows of 

hot, gas-rich volcanic rock; and an 

enormous plume of a sh . The 

water-soaked landslide debris 

produced a series of dense slurries that raced downstream and 

nearly severed Interstate Highway 

5 and the AMTRAK rail line 

connecting Portland, Oregon, and 

Seattle, Washington. These debris 

flows brought shipping on the 

Columbia Ri ver to a halt and 

came close to blocking coolingwater intakes at an operating 

nuclear powerplant. These events 

transformed a lush landscape of 

dense, green forest into a dusty 

volcanic wasteland and killed 57 

people who were too close to the 

mountain. The eastern half of the 

State, where people were virtually 

unaware of any volcanic hazard, 

was blanketed with ash. The 

death toll, though large, could 

have been much, much higher 

without the previous warnings 

and resultant land closure. Luck 

also played a role in keeping the 

number of fatalities down. Had 

the eruption occurred on Monday 

rather than Sunday, several 

hundred loggers, working in an 

area near the volcano but outside 

the closed area, would have died. 

During the next decade, continued 

enforcement of restricted zones 

and careful observation and 

prediction of activity warned the 

public of impending eruptions, 

and no additional lives were lost. 

Research into what had caused 

the catastrophic eruption led to 

increased appreciation of the 

inherent instability of high, snowcovered volcanoes and the hazards they pose . 

Eruptions from U.S. volcanoes can generate 

serious volcanic hazards, any of which can be 

deadly: glowing rivers of molten rock (lava 

flows), devastating shock waves and fiery 

blasts of debris from volcanic explosions (pyroclastic surges), red-hot avalanches of rock frag -

ments racing down mountainsides (pyroclastic 

flows), and suffocating blankets of volcanic ash 

falling from the sky (pyroclastic falls) . But that 

is not all. A n umber of equally deadly processes involve water (Pierson, 1989), and in fact, 

over 80 percent of the more than 28,500 volcano-related fatalities this past decade were 

caused by such hydrologic processes. Although 

many hydrologic hazards at volcanoes are directly associated with eruptions, others are not. 

It is the latter that are especially dangerous 

because debris avalanches, debris flows, and 

floods can strike without warning, for example, 

following periods of heavy rainfall, and they 

occur with a greater frequency than eruptions. 

Furthermore, hydrologic hazards typically endanger populations in river valleys a t considerable distances from their source volcanoesMount St. Helens Reawakens 3 
as far as 150 kilometers downstream. Within 

the last few thousand years, large debris avalanches, debris flows, and (or) floods have occurred at most volcanoes in the Cascades and 

in Alaska (Heath, 1960; Hyde and Crandell, 

1978; Riehle and others, 1981; Beget, 1982; 

Siebert, 1984; Gallina and Pierson, 1985; Cameron and Pringle, 1986; Osterkamp and others, 

1986; Riehle and others, 1987; Siebert and others, 1987; Major and Newhall, 1989; Major and 

Scott, 1988; Scott, 1988; Siebert and others, 

1989; Nye and Turner, 1990; Scott and others, 

1990). 

Damaging earthquakes and sea waves (tsunami) may also be closely related to volcanoes 

and volcanic activity. Large earthquakes related to intrusion of magma into Hawaii's active 

rift zones of Mauna Loa and Kilauea have 

caused extensive damage on land and also triggered tsunami in 1868 and 1975 that devastated 

low-lying coastal areas (Tilling and others, 

1976). Large landslides from Alaskan volcanoes 

near the sea have also generated tsunami that 

destroyed coastal villages (Kienle and others, 

1987). Recent research in Hawaii has shown 

that much larger tsunami have, in the more 

distant past, washed as much as 366 meters up 

on some of the islands (Moore and Moore, 

1984). These waves appear to have been generated by gigantic submarine landslides that removed large parts of the Hawaiian volcanoes 

(Moore and others, 1989). These colossal failures have also torn away and submerged subaerial parts of islands. 

A short list of notable eruptions and other 

volcanic activity at U.S volcanoes during the 

20th century is given in table 1. A more complete listing of U.S. volcanoes active within the 

last 2,000 years, as well as older volcanic areas 

that have active geothermal systems, have 

shown recent signs of unrest, or which represent a particularly catastrophic event are shown 

in Appendix 1. Not listed are several dormant 

volcanic fields on the U.S. mainland that have 

erupted in the past 10,000-50,000 years and 

which could erupt again (Smith and Luedke, 

1984; Simkin and others, 1981; Miller, 1989). 

The eruption recurrence intervals for such volcanic fields are large; many of these fields have 

4 Living With Volcanoes 

a deceptively tranquil appearance, show no obvious signs of their violent past, and the land 

overlying and surrounding these fields is used 

for agriculture, recreation, or is developed for 

commercial or residential use. However, the 

possibility remains that one or more of the currently inactive volcanic fields could erupt 

again, probably preceded by a period of unrest 

sufficient to prepare for renewed eruption. 

The hazards posed by the U.S. volcanoes 

provide a fairly complete sampling of hazards 

shown by volcanoes worldwide. The variety of 

hazards, in conjunction with the relative abundance of volcanic systems having eruption potential in the U.S., are difficult challenges for 

the U.S. Geological Survey's Volcano Hazards 

Program. To address these challenges, we rely 

on observations and studies made at currently 

active volcanoes to understand their past histories. The combination of present observations 

and the reconstructed history of volcanoes, 

both currently inactive and recently active, allows scientists to estimate the types of hazards 

and the likelihood of their occurrence for all 

potentially active or otherwise unstable volcanoes and volcanic areas in the U.S. We recognize, however, that an improved understanding of volcanic processes in itself is insufficient 

to mitigate volcanic hazards. Effective and 

timely communication of hazards information 

to emergency-management authorities before 

and during a volcanic crisis is equally, if not 

more, important in reducing risk. This publication summarizes the Volcano Hazards Program-its goals, the activities designed to 

achieve these goals, some key accomplishments 

of the past two decades, and a plan for work in 

the 1990's. Additional background information 

and bibliographic resources on volcanology 

and volcano hazards are given by Tilling 

(1989a, b). 

ACKNOWLEDGMENTS 

This summary of the Volcano Hazards Program, updated from Bailey and others (1983), 

was conceived at a workshop held in Vancouver, Washington, in November 1989, convened 

by Bob Christiansen, John Costa, and Chris 
Table 1. Notable eruptions of volcanoes in the United States during the 20th century 

[A complete listing of volcanoes and their eruptive history is given in Appendix 1] 

Volcano Year Eruption type Impact 

Novarupta, 

Alaska 

1912 . . . . . . . . . . . . . . . . Explosive; dome ........ . Largest eruption of the 20th century; produced 21 cubic 

kilometers of volcanic material, which is equivalent to 

230 years of eruption at Kilauea. Pyroclastic flow 

filled Valley of Ten Thousand Smokes, and as much as 

0.3 meter of ash fell161 kilometers away. 

(Katmai group). 

Lassen Peak, California . . 1914-1917 . . . . . . . . . . Explosive .............. . Pyroclastic flows, debris flows, and lava flows covered 

over 16 square kilometers. 

Mount St. Helens, 1980-1986 . . . . . . . . . . Explosive; dome ........ . Initial debris avalanche and lateral blast on May 18, 

1980, removed the upper 396 meters of the volcano, 

killed 57 people, and triggered debris flows that 

temporarily stopped shipping on the Columbia River 

and disrupted highways and rail lines. The blast 

devastated 596 square kilometers, and destroyed 

timber valued at several millions of dollars. 

Measurable amounts of ash fell as far east as North 

Dakota. Subsequent to May 1980, the volcano 

produced pyroclastic flows, debris flows, and lava 

domes. 

Washington. 

Kilauea, Hawaii . . . . . . . . . Ongoing since 1983 Lava flows ............. . Nearly 78 square kilometers covered by lava and over 

180 dwellings destroyed including, in 1990, the entire 

historic community of Kalapana. 121 square 

hectometers of new land added to the Island of 

Hawaii. 

Mauna Loa, Hawaii. . . . . . 1984 . . . . . . . . . . . . . . . . Lava flows ............. . Hilo, largest city on the Island of Hawaii, threatened. 

Augustine Volcano, 1986 . . . . . . . . . . . . . . . . Explosive; dome ........ . Ash plume disrupted air traffic and deposited ash in 

Anchorage. A dome built in the crater led to fear of 

dome collapse triggering a tsunami along the east 

shore of Cook Inlet, as happened in 1883. 

Alaska. 

Redoubt Volcano, 

Alaska. 

1989-1990 . . . . . . . . . . Explosive; dome ........ . Debris flows caused temporary closing of the Drift 

River Oil Terminal. A 747 jet aircraft temporarily lost 

power in all4 engines when it entered the volcanic 

ash plume, and it would have crashed had its engines 

not been started just 1,219 meters above the mountain 

peaks toward which it was heading. 

Newhall. The workshop brought together persons from the Water Resources and Geologic 

Divisions of the U.S. Geological Survey to discuss all aspects of the Volcano Hazards Program. A list of the workshop participants is 

given in Appendix 4. Working groups were 

formed to cover different aspects of the program. Leaders of the working groups prepared 

a written summary of goals and accomplishments, derived in part from contributions 

made by individual workshop participants, and 

the discussions held by the group. Early versions of the present manuscript were substantially improved through reviews by Steve 

Brantley, John Costa, Dave Hill, Chris Newhall, Don Swanson, and Bob Tilling. Tables 

were checked for accuracy by Dan Dzurisin, 

Dan Miller, and Tom Miller. The authors are 

indebted to the following individuals for contributing illustration material: Darcy Bevens, 

Steve Brantley, John Dvorak, Chris Janda, Dick 

Janda, Bob Krimmel, John Langbein, Steve Malone, Susan Mayfield, Dan Miller, Tina Neal, 

Chris Newhall, Keith Ronnholm, Lyn Topinka, 

and Joyce Warren. We are indebted to Tom 

Simkin of the Smithsonian Institution Global 

Volcanism Project for providing information 

from the database on Global Volcanism (see 

Acknowledgments 5 
Simkin and others, 1981) on volcanoes active in 

the past 2,000 and 200 years. The final version 

of the manuscript was reviewed by Jeff Troll, 

Carolyn Donlin, Chris Newhall, and Bob Tilling. Tilling in particular deserves our thanks 

for his efforts to increase the readability of this 

document by a general audience, and for his 

assistance in facilitating the editorial process. 

PROGRAM GOALS AND ACTIVITIES 

THROUGHOUT THE 1980'S 

The Volcano Hazards Program was formed 

with the goals of: 

• preventing loss of life and property resulting from volcanic eruptions and volcanorelated hydrologic events, and 

• minimizing economic hardship and social 

disruption that commonly occur when volcanoes threaten to erupt. 

To understand the hazards we extensively 

monitor currently active volcanoes, and concurrently conduct a vigorous program of research in volcanic processes with the end goal 

of discovering how volcanoes work. The U.S. 

Geological Survey (USGS) provides volcanohazards information at a number of levels: to 

Federal, State, and local officials, to local citizens, and to other concerned groups. In delivering hazard information that others must act 

on, the USGS does not dictate or even recommend specific mitigation measures, because 

such measures must be balanced by social and 

economic considerations beyond USGS mandate or expertise. Rather, the program provides 

information about volcanic hazards that will 

help people to choose and manage the risks associated with living near a volcano. 

The Volcano Hazards Program includes the 

following activities: 

• 

• 

Identifying potentially active volcanoes . 

Directly observing, measuring, and analyzing volcanic unrest. 

6 Living With Volcanoes 

• Studying and monitoring volcanic and hydrologic processes associated with different kinds of volcanoes and eruptions. 

• Reconstructing eruptive and erosional history of volcanoes through study of morphologic and depositional evidence of past 

events. 

• Studying effects of volcanic emissions on 

the atmosphere, soil, and water supply. 

• Preparing geologic and hydrologic volcano 

hazard maps for individual volcanoes. 

• Coordinating with officials responsible for 

public safety prior to and during eruptive 

activity. 

• Communicating information about potential hazards at a volcano, including the 

likelihood of their occurrence and potential 

areas of impact, to public officials, emergency management personnel, and the population at risk. 

The activities of the program enable the accumulation of fundamental information on the 

nature of volcanic processes and associated 

hazards and, at the same time, provide the 

means for public officials to respond rapidly 

and effectively to volcanic crises. Program activities are carried out at many USGS facilities 

(table 2) and involve the active collaboration of 

other agencies-Federal, State, and local-and 

several academic institutions (table 3). 

VOLCANO OBSERVATORIES: 

TAKING THE PULSE OF ACTIVE VOLCANOES 

To study active volcanism, the Volcano 

Hazards Program depends principally on the 

research and monitoring conducted at three 

permanent installations: the Hawaiian, Cascades, and Alaska Volcano Observatories. Each 

observatory provides continuous and periodic 

monitoring of the seismicity, other geophysical 

changes, ground movements, gas chemistry, 

and hydrologic conditions and activity between and during eruptions. They also provide 
Table 2. Facilities and activities of the U.S. Geological Survey Volcano Hazards Program 

Facility 

Alaska Volcano Observatory 

(AVO). 

Location 

Anchorage, Alaska 

(headquarters). 

AVO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fairbanks, Alaska ...... . 

Activities 

Coordination of Volcano Hazard Program activities in 

Alaska. 

Volcano observation, research, and hazard evaluation for 

Alaska. 

Cascades Volcano Observatory 

(CVO). 

Vancouver, Washington . . . . Volcano observation, hydrologic and geologic monitoring, 

research, and hazard evaluation for the Cascade Range 

and western U.S. (monitoring includes Yellowstone and 

Long Valley Calderas); mapping of Cascades volcanoes. 

Hawaiian Volcano Observatory Hawaii Volcanoes National 

(HVO). Park, Hawaii. 

Headquarters Reston, Virginia ............. . 

Volcano observation, monitoring, research, and hazard. 

evaluation for the Hawaiian Islands. 

Program coordination; research in volcano processes and 

products. 

Western Regional Center . . . . . . . Menlo Park, California ...... Program coordination; monitoring Long Valley Caldera (in 

conjunction with CVO); research in volcanic processes and 

products; mapping of Cascades volcanoes. 

Central Regional Center .. . 

Flagstaff Field Center .. . . . . 

Denver, Colorado............ Research in volcanic processes and products. 

Flagstaff, Arizona..... .. ... .. Research in volcanic processes and products. 

a detailed record of eruptions in progress. 

These observations serve to characterize eruptive behavior, identify the nature of precursory 

activity leading to eruption, define the processes by which different types of deposits are emplaced, and specify the hazards that could be 

unleashed by each kind of eruption. From diHawaiian Volcano 

Observatory, 

Hawaii Volca noes 

National Park, 

Hawaii. 

Halemaumau 

Crater and Kilauea 

Caldera in the 

background. 

Photograph by J.D. 

Griggs. 

rect observation of precursory signs, it is possible to anticipate eruptions. Underlying all observatory operations is an ongoing program of 

fundamental research in volcanic processes, 

supplemented by collaborative studies conducted at other USGS centers (table 3). Such research typically includes direct interpretation 

Volcano Observatories: Taking t he Pulse of Active Volcanoes 7 
of the monitoring and eruption data, and it 

leads to formulation of conceptual models that 

can be tested by theoretical or laboratory simulations of volcanic systems. 

The Hawaiian Volcano Observatory (HVO) 

is the U.S. Geological Survey's oldest such facility, founded in 1912 by Thomas A. Jaggar and 

run continuously by the USGS since 1948 (Heliker and others, 1986). It is located on the summit of Kilauea, one of the most active volcanoes 

in the world, on the Island of Hawaii. With the 

frequent eruptions at Kilauea and nearby Mauna Loa, HVO is a training ground for most of 

the volcanologists at the USGS. Many volcanomonitoring techniques used worldwide were 

originally developed at HVO, which is a testing 

ground for new techniques and instruments. 

The existence of HVO gave the USGS the 

unique capability of responding to activity at 

other U.S. volcanoes. When Mount St. Helens 

reawakened in March 1980, the USGS was well 

prepared to respond to the crisis. Scientists who 

had previously deciphered the volcanic history 

of Mount St. Helens, together with HVO alumni, quickly assembled to monitor the seismic activity and steam explosions. All worked together with the many agencies and public officials 

who were anxious to know when and if a large 

eruption was going to occur and what hazards 

it might create. Guided by USGS information, 

public officials designated zones of restricted 

access, and the loss of life from the May 18th 

eruption was thereby minimized, even though 

the timing of this event could not be precisely 

predicted. 

After the devastating explosive eruption in 

1980, the Cascades Volcano Observatory (CVO), 

in Vancouver, Washington, was founded and 

staffed with hydrologists, geologists, geochemists, and geophysicists (Brantley and Topinka, 

1984). The observatory quickly broke new 

ground in its study of the ongoing eruption 

cycle at Mount St. Helens. In mapping and interpreting the origin of the deposits of the May 

18 eruption, scientists had the unique advantage of direct observation of the landslides, 

eruption, and volcanic debris flows. Monitoring 

the growth of the lava dome in the crater of 

Mount St. Helens resulted in accurate predic8 Living With Volcanoes 

tions, 1 to 3 days in advance, of 16 out of 17 

dome-building eruptions-an unprecedented 

feat in the young science of volcanology. 

In 1988, the USGS added a third volcano 

observatory, the Alaska Volcano Observatory 

(AVO), in Anchorage and Fairbanks, Alaska, to 

expand and coordinate existing monitoring of 

the many active volcanoes along the Alaska 

Peninsula and in the Aleutian Islands. Many 

international flightpaths lie directly over Alaska, and the frequent eruptions of these volcanoes pose a serious hazard to aircraft far 

downwind. Study of Alaskan eruptions also 

provides more frequent opportunities to study 

volcanic activity similar to that of the less frequently active Cascade Range volcanoes. 

In May 1980, just 1 week after the eruption 

at Mount St. Helens, a strong earthquake swarm 

occurred at Long Valley, California, site of a 

huge eruption of silicic magma about 700,000 

years ago. The most recent volcanic activity in 

the area resulted in the formation of lava domes 

550 years ago, accompanied by phreatic explosions that blanketed much of eastern California 

and western Nevada with volcanic ash (Bailey 

and others, 1976; Miller, 1985). Following the 

1980 earthquakes, the USGS began monitoring 

Long Valley by setting up an observatory-like 

project operated from the USGS center in Menlo 

Park, California. Studies conducted since 1980 

have documented almost 2 feet of uplift of the 

ground within the Long Valley Caldera and 

have accurately located earthquakes occurring 

as swarms in and around the caldera, the most 

recent of which took place in 1990 and 1991. 

The work at Long Valley is designed to monitor 

and interpret the current unrest and to make 

forecasts of any activity that might occur. Thus, 

the Long Valley project effectively constitutes a 

fourth volcano observatory in function and responsibilities, if not in name. The largest possible volcanic event at Long Valley, a catastrophic explosive eruption associated with renewed 

caldera collapse, is also the most difficult to 

forecast because of the long time interval between such eruptions and the absence of historically documented large caldera-forming eruptions anywhere in the world (see Newhall and 

Dzurisin, 1988). 
Table 3. Collaborative work with the U.S. Geological Survey (USGS) Volcano Hazards Program 

USGS facility 

Alaska Volcano 

Observatory (AVO). 

Cascades Volcano 

Observatory (CVO). 

Hawaiian Volcano 

Observatory 

(HVO). 

USGS Headquarters, 

Reston, Virginia. 

Collaborating organization 

Geophysical Institute of the University of 

Alaska. 

State of Alaska, Division of Geological 

and Geophysical Surveys. 

University of Washington Geophysics 

Program. 

University of Utah ....................... . 

Office of Foreign Disaster Assistance 

Volcano Disaster Assistance Project 

(OFDA VDAP). 

Nature of work 

Volcano monitoring. Maintenance of the Augustine 

and Iliamna seismic networks. 

Geologic mapping of Alaskan volcanoes. 

Operation of the Washington and northern Oregon 

seismic network. 

Operation of seismic network around Yellowstone 

Caldera. 

Funding USGS Volcano Crisis Assistance Team 

(VCAT) for foreign volcano assistance. 

State of Hawaii, Department of Land and Shared funding toward development of Geographic 

Natural Resources. Information Systems (GIS) capability at HVO; sharing 

of digital geographic and geologic data. 

University of Hawaii at Hilo, Center for 

Study of Active Volcanism (CSAV). 

National Aeronautics and Space 

Administration (NASA) Jet Propulsion 

Laboratory. 

Earth Observing System (EOS; multiagency effort including University of 

Hawaii at Manoa). 

National Park Service ................... . 

Commonwealth of the Northern 

Marianas. 

U.S. Department of Energy ............. . 

U.S. Agency for International 

Development (AID). 

Summer training program in volcano monitoring for 

foreign applicants. 

Remote sensing of Hawaiian volcanoes. 

Remote monitoring of Hawaiian volcanoes. 

Assistance in volcano monitoring when there is 

volcanic activity within Hawaii Volcanoes National 

Park. 

Funding for monitoring active volcanoes in the 

Marianas Islands. 

Funding continuous gravity observations on Kilauea. 

Coordination and funding of volcano crisis assistance 

abroad. 

Smithsonian Global Volcanism Project . . Publish maps (some jointly) of volcanoes and their 

activity. USGS provides information to the 

Smithsonian for their monthly bulletin of worldwide 

volcanic activity. 

National Oceanographic and Atmos- Study of undersea volcanism. 

pheric Administration (NOAA). 

Federal Aviation Administration (FAA) Developing appropriate levels of alert and response to 

prevent commercial, as well as private, aircraft from 

flying into volcanic ash clouds. 

USGS Office of International Geology . . . Coordinating foreign exchange programs (for example, 

the 1990-1991 exchange of U.S. Geological Survey 

volcano observatory personnel with personnel from 

the Institute of Volcanology, Petropavlovsk, 

Kamchatskii) and facilitating foreign collaborations in 

volcano monitoring (for example, the recently 

completed multiyear collaboration with the 

Volcanological Survey of Indonesia). 

Volcano Observatories: Taking the Pulse of Active Volcanoes 9 
HOW SC/EIVTlSTS STUDY VOLCANOES 

Taking a Volcano's Pulse 

The three USGS volcano 

observatories and the Long Valley 

project have the following goals in 

common: 

• Research directed toward understanding volcanic processes 

and products. 

• Evaluation of the ongoing 

hazards posed by the active 

volcanoes. 

• Delivery of warnings to public 

officials regarding these 

hazards. 

To realize these goals, it is 

necessary to conduct visual and 

instrumental monitoring of 

volcanic activity. Monitored 

changes common to each volcano 

include the following : 

Seismicity. Earthquakes commonly provide the earliest warning 

of volcanic unrest, and earthquake swarms immediately precede most volcanic eruptions. 

Monitoring seismicity at a site in the crater of Mount St. Helens, Washington. 

Data from several such seismometers are telemetered via radio to Cascades 

Volcano Observatory, Vancouver, Washington, and to Seattle, Washington, 

where the location and magnitude of the earthquakes are determined using 

computer-based techniques. Photograph by Lyn Topinka . 

0.0 

(/) 0 

a: 

w 

Iw 4.0 EXPLANATION 

~ Magnitude 0 0 0 0 0 0 

...J 

Q 0 5.0+ 8.0 0 '0 0 0~ 000 

z 0 4.0+ 0~ 0 0 ~ 0 0 

0 0 0 0 0 

::r.' 0 3.0+ 0 0 

I- 12.0 0.. 

w 0 2.0+ 

0 0 

0 1.0+ 

16.0 

March April May 

Earthquakes (denoted by circles) beneath Mount St. Helens, March 1 to 

May 31, 1980. Note the abrupt onset of earthquakes around March 17, 

building quickly to continuous, shallow seismicity from March 26 

(beginning of explosions) to the climactic eruption on May 18. There 

was no additional increase in seismicity immediately preceding the May 

18 event. Coincident with eruptions on May 18 and May 25 (denoted by 

arrows), earthquake hypocenters trace the movement of magma from 

depths above and below 5 kilometers, where there may have been a 

shallow magma storage area . Modified from Malone (1990). Used with 

permission. 

10 Living With Volcanoes 

Ground movements. Geodetic 

networks are set up to measure 

the changing shape of the 

volcano surface caused by the 

pressure of magma moving 

underground. Techniques 

commonly used include electronic distance measurement 

using a laser light source 

(EDM); measurement of tilt, 

both electronically and by 

repeated leveling of triangular 

arrays; and standard leveling 

surveys to obtain elevation 

changes. Additionally, very 

simple and inexpensive techniques, such as measuring 

crack openings using a steel 

tape, or noting changes in 

water level around a crater 

lake, have proven useful in 

certain situations. Upward and 

outward movement of the 
ground above a magma storage 

area commonly occurs before 

eruption. Localized ground 

displacement on steep volcanoes may indicate slope 

instability precursory to mass 

failure. 

Geophysical properties. Changes 

in electrical conductivity, 

magnetic field strength, and 

the force of gravity also trace 

magma movement. These 

measurements may respond to 

magma movement even when 

no earthquakes or measurable 

ground deformation occurs. 

Gas geochemistry. Changes in 

fumarole gas composition, or 

in the emission rate of SOz 

and other gases, may be 

related to variation in magma 

supply rate, change in magma 

type, or modifications in the 

pathways of gas escape induced by magma movement. 

HOW SC/ENTJSTS STUDY VOLCANOES 

Monitoring horizontal distance changes at Kilauea, 

Hawaii, using a conventional electronic distance 

measuring (EDM) instrument; the red laser beam sends 

a signal and the round-trip transit time of that signal 

gives a very accurate distance measurement. Snowcovered Mauna Loa in background. Photograph by J.D. 

Griggs. 

Hydrologic regime. Changes in ground 

water temperature or level, rates of 

streamflow and transport of stream 

sediment, lake levels, and snow and 

ice accumulation are recorded to 

evaluate (1) the role of ground 

water in generating eruptions, (2) 

the potential hazards when hot, 

energetic volcanic products interact 

with snow, ice, and surface streams, 

and (3) the long-term hazard of 

infilling of river channels leading to 

increased flood potential. 

Reconstructing a 

Volcano's History 

Results of two-color laser ground-deformation measurements of 7 

base lines at Long Valley Caldera, California. Note the recent (starting 

in late 1989) lengthening of lines, particularly for base lines 4 to 7, 

across the caldera, interpreted to be the result of magma movement 

to shallower depths beneath the caldera. 

Direct observations of volcanoes 

before, during, and after eruptions are 

essential to understanding a volcano's 

current behavior. The following studies 

complement information gained from 

How Scientists Study Volcanoes 11 
HOW SCIENTJSTS STUDY VOLCANOES 

Monitoring ground 

tilt in Kilauea 

Caldera, Hawaii, 

using single set-up 

leveling (also 

called dry tilt). 

Photograph by 

J.D. Griggs. 

monitoring and allow specification of the entire history of 

activity at a given volcano or 

volcanic field. 

Geologic mapping places layered 

and more irregular deposits in 

the proper stratigraphic order 

and establishes their thickness 

and areal extent (and thus 

volume). Field descriptions of 

stratigraphic units are used to 

classify deposits and interpret 

the type of eruption that 

produced them. Mapping of 

ash deposits is used to correlate widely separated stratigraphic sections associated 

with a given volcano. Dating 

of ash layers is especially 

valuable to bracket ages of 

other, less extensive, deposits 

in individual stratigraphic 

sections. 

Dating of deposits establishes the 

time intervals in which eruptions or hydrologic events 

occurred. Techniques commonly used for young deposits are: 

Carbon-14. This technique is used 

where eruptions overlie or 

incorporate vegetation or 

organic-rich soil and the 

carbon-bearing material is 

preserved. 

12 Living With Volcanoes 

Tree rings. Traumatic injuries to 

trees are represented by 

interruption or distortion of 

growth rings. In some cases, 

the season in which the event 

occurred can be specified 

based on knowledge of the 

yearly cycles of tree-ring 

growth. 

0 4 KILOMETERS 

N 

t 

Paleomagnetism. In some areas, it 

has been possible to calibrate 

yearly changes in the position 

of the Earth's magnetic pole 

over the past several hundreds 

or thousands of years. In such 

cases the magnetic directions 

preserved in a series of eruptive deposits may be used to 

specify their approximate age. 

\(ILAUEA 

EXPLANATION 

0 100 

- Vector scale DOWN 

-100 - Vertical uplift(+) or 

subsidence (-) contour- In millimeters 

Contoured elevation changes and ground tilt vectors for the period JuneAugust 1981, following underground magma emplacement (intrusion) on 

southwest rift zone of Kilauea. Vector scale in microradians. 
Understanding Volcanic 

and Hydrologic Processes 

Direct observation of volcanic 

and hydrologic events gives 

important but incomplete insights 

into the nature of volcano hazards. The following topics represent some of the avenues pursued 

to gain a fuller understanding of 

volcanic processes that control 

hazardous events. 

Numerical modeling is used to 

test our understanding of 

physical processes, and hazard 

predictions can eventually be 

made on the basis of modeled 

events. Volcano-related processes amenable to modeling 

include (1) the gravity-driven 

flow of lava, hot pyroclastic 

debris, landslide debris, wa tersaturated mixtures of mud and 

rock, and water floods; (2) the 

dispersal of volcanic ash 

plumes and thickness of ash 

accumulation on the ground; 

(3) the development of eruption- or landslide-induced 

waves; (4) the time of occurrence and magnitude of 

outbreak floods from lakes 

dammed by volcanic debris; 

and (5) the flow of ground 

water and the dynamics of 

hydrothermal systems. 

Cl 

z 

0 

800 tStreamflow 

rtHOW SCIENTJSTS STUDY VOLCANOES 

Experimental research is necessary to model volcanic processes that cannot be studied 

directly or safely in the field 

or are too complicated to 

model numerically. Experiments can be designed to 

simulate volcanic conditions 

and infer possible consequences of volcanic activity. For 

example, a gelatin mold 

injected with a colored fluid 

mimics patterns of subsurface 

magma movement. Specially 

designed flumes simulate the 

properties of dense slurries 

and help scientists to better 

u n derstand the development 

and movement of debris flows. 

Other topics, su ch as the origin 

of magmas by melting in th e 

Earth's mantle, and their 

subsequent crystallization, can 

be studied by a combination of 

labor atory experiments, 

numerical mod eling, and 

interpretation of chemical 

variation in th e erupted lavas. 

1 

-

-

,500 

C') 

~ 

Ox 

i=a: 

A scientist from the Cascades Volcano 

Observatory, Vancouver, Washington, 

in a cablecar measuring flow 

discharge and sediment load during a 

flood in the Toutle River, a watershed 

heavily impacted by the 1980 eruption 

of Mount St. Helens. By monitori ng 

such hydrologic changes, scientists 

are able to determine how much 

sediment will be carried downstream 

to clog channels and thereby cause 

floods . Photograph by Lyn Topinka. 

u.i til 600 ClUJ 

ffi :r: [l_ 0 (/) 400 ~a: 

ow 

~t;j 

t-

-

1=-

~i~ ' ~ "

,

v , ''"' '"'''"""' ,.,,.,. 

\ 

~, 

" 

- 1 

-

-

,000 ~ ~ 

::::; wa: 

o w z [l_ 

OUJ 

-= 500 O:;i; 

t-<( 

z a: 

Streamflow rate and excessively high suspendedsediment concentration measured by Cascades 

Volcano Observatory staff on an eruptiontriggered flood wave from Mount St. Helens on 

March 79, 1982, 73 ki lometers downstream from 

w :;i; 20 the volcano 's crater on the Toutle River. a:o 

~iii ::J 

0 

~ 

ort0 

I 

I 

,; 

1 

2400 

March 19 I 

\ 

\ - "-, .... _ -

---------------- 0600 1200 

TIME IN HOURS 

March 20 

0 

W C) 

:;i;:J 

Ci =o! W :;i; 

(/) ~ 

How Scientists Study Volcanoes 13 
A VOLCANO'S HISTORY: 

KEY TO ASSESSMENT OF HAZARDS 

Any volcano is the sum total of past constructive and destructive processes, both volcanic and hydrologic, that hav~ occurred over a 

period of time, usually thousands of years. 

When the pattern, magnitude, and frequency of 

past events can be determined and evaluated in 

light of information gained by studying modern eruptions, reasonable predictions of future 

activity can be made. Thus, knowing a volcano's history is crucial to understanding its potential future behavior. The essential link 

between the reconstruction of volcanic history 

and study of volcanic eruptions was recognized 

late in the 19th century. In 1882, three years after the U.S. Geological Survey was founded, 

Clarence Dutton was asked to head a Division 

of Volcanic Geology within the USGS. Dutton 

was sent to Hawaii "with the purpose of studying the features and processes of a volcano in 

action, and thus obtaining the practical knowledge which is essential to the investigation of 

extinct volcanoes" (Dutton, 1884, p. xxvi). 

The principal means of understanding a 

volcano's history are geologic mapping and 

dating of volcanic deposits whose stratigraphic 

positions are known. Understanding the processes that produced the deposits depends on 

study of active volcanoes. Eruption style and 

vigor can be determined for older deposits by 

matching a deposit produced during an observed volcanic event with a similar deposit in 

a geologic section. By determining the kinds of 

eruption represented in a volcano's deposits, 

its eruption history can be reconstructed. Once 

all or part of this eruption history is known, 

geologists can discern the patterns, if any, in 

its eruptive cycle. Such patterns can help volcanologists to determine when a volcano may 

erupt again and the type of hazards expected 

from renewed eruption. 

In all of the currently active volcanic areas 

in the United States, an effective collaboration 

Pahoehoe lava issuing from a fissure eruption near Puu Oo vent, Kilauea east rif~ zone, Hawaii. Photograph at top 

of facing page shows the resulting deposits of this event. Photograph by J .D. Gnggs. 

14 Living With Volcanoes 
is maintained between those who study active 

volcanism and those who study the prehistoric 

eruptions and fill in the eruptive history; many 

individuals do both. In Hawaii, a new geologic 

map of the Island of Hawaii and its active volcanoes is being compiled (Wolfe and others, 

unpub. data) and a USGS general-interest publication on the volcanic and seismic hazards of 

the island has been published (Heliker, 1990). 

These layers of thin pahoehoe 

lavas, exposed in a roadcut, were 

produced during the 1970-74 

Mauna Ulu eruption of Kilauea, 

Hawaii. The pahoehoe flows have 

smooth tops and central gas 

cavities. Photograph by Taeko J. 

Takahashi. 

Freshly cooled pahoehoe lava 

surface, Kilauea . Photograph by 

Taeko J. Takahashi. 

Geologists mapping and dating deposits from 

individual volcanoes have produced a series of 

geologic hazard evaluations for volcanoes in 

the Cascade Range (for example; Mount Baker-Hyde and Crandell, 1978; Mount RainierCrandell, 1973; Mount St. Helens-Crandell 

and Mullineaux, 1978; Mount Hood-Crandell, 

1980; Mount Shasta-Miller, 1980). Teams of 

geologists and hydrologists at CVO are evaluA Volcano's History: Key to Assessment of Hazards 15 
Debris flow after coming to rest in the Toutle River drainage during the eruption of May 18, 1980, at Mount St. 

Helens, Washington. Photograph by Bob Krimmel. 

ating the past occurrence of debris avalanches, 

debris flows, and floods at a number of volcanoes, as well as carrying out research to better 

understand how these hydrologic hazards can 

be triggered and how they behave once triggered (Voight and others, 1983; Crandell and 

16 Living With Volcanoes 

others, 1984; Pierson and Scott, 1985; Meyer 

and others, 1986; Laenen and Orzal, 1987; 

Siebert and others, 1987; Scott, 1988; Glicken 

and others, 1989; Major and Newhall, 1989; 

Pierson and others, 1990; Scott and others, 

1990). 
In Alaska, geologic mapping and hazard 

assessment are just beginning at the most hazardous volcanoes in the Cook Inlet area. Studies also are being conducted at sites in the U.S. 

where seismic activity and ground deformation 

suggest the possibility of future eruptions. 

Long Valley and Yellowstone Calderas in the 

continental interior are areas where recent geologic mapping has shown the occurrence of 

prehistoric volcanic activity widely ranging in 

scale from small basaltic eruptions, through exSequence of older debris-flow deposits in Toutle River 

valley approximately 60 kilometers downstream from 

Mount St. Helens, Washington. These massive flows 

originated 2,500-3,000 years ago as outbreak floods 

from a lake dammed by volcanic deposits. Photograph 

by Tom Pierson . 

plosive eruptions the size of the 1980 eruption 

of Mount St. Helens, to catastrophic calderaforming eruptions of a magnitude never witnessed in recorded history (Bailey and others, 

197 6). Both areas are seismically active and 

show episodic uplift of the ground surface; the 

seismic activity and geodetic changes are being 

closely monitored by USGS personnel supported under the Volcano Hazards Program (Dzurisin and others, 1990; Hill and others, 1990). 

From the mapping and dating of volcanic 

and volcaniclastic deposits, geologists can determine the eruptive and mass-failure history 

for a given volcano, from which the nature, 

size, and frequency of previous hazardous 

events can be specified. This history can then 

be used to predict the type and likelihood of 

future events. The most common means by 

which a volcano's history and potential for future activity can be presented is a map outlining areas of risk from a particular kind of volcanic or hydrologic hazard. The hazard zones 

must outline an area likely to be affected by a 

given kind of event and should also give some 

idea of the recurrence interval for that event 

(see Crandell and Mullineaux, 1975). Thus, the 

criteria used to specify hazard zones must be 

based on the following: (1) the type of activity 

(for example, debris flow, lava flow, ash fall); 

(2) the magnitude of a typical event, expressed 

as distance traveled or area covered, and (3) 

the frequency of occurrence, as deduced from 

the historical and geologic record. 

Maps have been prepared for several active 

volcanoes in the Cascade Range that outline 

the hazards from lava flows, pyroclastic flows, 

debris flows, and floods (Crandell and others, 

1979). The mapping and hazard assessment 

completed for Mount St. Helens in the 1970's 

resulted in publications (Crandell and others, 

1975; Crandell and Mullineaux, 1978) that accurately forecast an eruption before the end of 

the century. The May 1980 eruption impacted 

areas indicated as being at risk on a hazard 

map published in 1978 (Crandell and Mullineaux). Another hazard-zone map depicting 

lava-flow hazards on the Island of Hawaii has 

recently been published (Heliker, 1990). Hazard-zone maps are perhaps the most easily unA Volcano's History: Key to Assessment of Hazards 17 
WA~R, ROCK, AND GRAVITY: 

A PO~NTIALL Y DEADLY COMBINATION AT VOLCANOES 

Research conducted at Mount 

St. Helens and elsewhere has 

shown that even small eruptions 

of hot volcanic material can 

almost instantaneously melt large 

volumes of snow and ice. The 

resulting floods of meltwater can 

erode and incorporate several 

times their original volume in 

new sediment and water, forming 

debris flows-dense, powerful, 

and fast-moving mixtures of mud, 

rock, and water having the 

consistency of wet concrete-that 

can travel far down valleys 

heading on the volcano. For 

example, the eruption at Nevado 

del Ruiz in November 1985 

ejected a very small amount of 

magma-only about 3 percent of 

that erupted at Mount St. Helens. 

Yet, this tiny eruption generated 

high-volume debris flows that 

killed more than 23,000 people. A 

more recent example took place 

on January 2, 1990, during the 

eruption of Redoubt Volcano in 

Alaska . The rapid melting of 

snow and ice by a pyroclastic 

flow moving across Drift Glacier 

resulted in a flood and debris 

flow, larger than the Mississippi 

River at flood stage, that quickly 

moved down the Drift River 

valley. No lives were lost during 

this event, but a valuable oil 

storage terminal located at the 

mouth of the valley was closed 

temporarily because of the risk of 

further debris flows. Debris flows 

can also be generated when a 

volcano is inactive, typically 

during or following heavy rainfall, when unconsolidated volcanic debris on steep slopes becomes 

water saturated. 

As a direct result of research 

at Mount St. Helens, combined 

with experience of the 1985 Ruiz 

disaster, these extremely hazardous events are now receiving 

much more scientific attention. 

The knowledge gained is now 

18 Living With Volcanoes 

Drift River Oil Terminal (circled) located within the Drift River valley, Alaska; 

the Drift River headwaters lie in glaciers and snowfields associated with 

Redoubt Volcano (center). Photograph by Robert McGimsey. 

Channel swept by large volcanic debris flow, North Fork Toutle River, 

Washington, approximately 35 kilometers downstream from Mount St. 

Helens, May 19, 1980. Photograph by Don Swanson. 

being applied in other volcanic 

terranes to assess the hazards 

posed by debris flows, which 

worldwide have caused some of 

the greatest losses of life. While 

the hazard posed by individual 

debris flows is generally understood, the frequency of their 

occurrence is poorly known. 

Hazards mapping at Mount 

Rainier has shown many more 

such flows in the recent geologic 

past than had been recognized 

previously. Parts of Tacoma, 
Washington, and many other 

smaller communities between 

Tacoma and Seattle lie within the 

reach of large debris flows originating high on the slopes of the 

mountain. 

Recent fieldwork at both 

oceanic and continental volcanoes 

around the world is demonstrating that structural failure ("sector 

collapse") of large parts of volcanic cones is not uncommon. 

Giant landslides in the Cascades, 

for example, have produced 

debris avalanches that have swept 

over as much as 440 square 

kilometers, depositing as much as 

25 cubic kilometers of debris. The 

May 18, 1980, debris avalanche 

and flow at Mount St. Helens, 2.8 

cubic kilometers in volume, raced 

35 kilometers downvalley at 

speeds as high as 253 kilometers 

per hour. Even larger failures of 

the oceanic volcanoes forming the 

Hawaiian Islands have occurred 

in the past. Single landslides can 

involve more than 1,000 cubic 

kilometers of material and remove 

as much as half of the subaerial 

island and 10 to 20 percent of the 

entire volcano. Significantly, large 

sector collapses may not necessarily occur during eruptive periods. 

In addition to the direct risk 

from debris flows and debris 

avalanches, voluminous deposition of volcanic material in 

valleys commonly forms unstable 

natural dams by blocking preexisting drainages. If the size and 

structural integrity of the blockage is insufficient to hold back 

the reservoir that will form (or 

withstand the erosion by overtopping flow), catastrophic failure 

of the dam will result. Such a 

hazardous situation may persist 

for months, years, or decades 

following an eruption. Another, 

less-obvious threat comes from 

the gradual infilling of river 

WATER, ROCK, AND GRAVITY: 

A POTENJJALL Y DEADLY COMBINATION AT VOLCANOES 

channels by sediment transported 

from highly erodible, volcanically 

disturbed landscapes following 

large eruptions. This sediment can 

aggrade channel beds with excess 

sand and gravel for tens to 

hundreds of kilometers downstream. Such aggradation promotes lateral migration of channels and may cause serious 

flooding during rainstorms, due 

to loss of channel capacity necessary to convey floodwaters. 

Sediment-retention dam constructed on Toutle River in Washington by U.S. 

Army Corps of Engineers to hold back the large volumes of sediment that 

would otherwise be carried downstream and clog Toutle and Cowlitz River 

channels. Photograph by Steve Brantley. 

Channel aggradation 1.6 kilometers upstream from mouth of Toutle River in 

Washington caused by the May 18, 1980, debris flow and avalanche at Mount 

St. Helens and by subsequent high sedimentation rates resulting from the 

new vast source of easily erodible sediment upstream. Photograph by Lyn 

Topinka . 

Water, Rock, and Gravity: A Potentially Deadly Combination at Volcanoes 19 
HAZARD-ZONE MAPS AND VOLCANIC RISK 

The purpose of hazard-zone 

maps is to give accurate information on the type and frequency of 

volcanic eruptions and consequent 

volcanic and hydrologic processes 

that could impact a given areainformation vital to sound landuse planning. In 1951, two decades before the first comprehensive hazard assessment for 

volcanoes in Hawaii, a developer 

could have felt secure in placing a 

subdivision on Kilauea's lower 

east rift zone knowing that: (1) 

Kilauea had not erupted at all for 

155°30' 

MAUNA LOA 

19°30' 

Kilauea 

19°15' 

the past 17 years, and (2) Kilauea 

had not erupted on its lower east 

rift zone since 1840, more than a 

century of inactivity. Such time 

periods are long by human standards and commonly influence 

judgment in land-use decisions. 

But he would have made a mistake . Kilauea became active again, 

at its summit, in 1952 and over 

the succeeding 38 years there 

were 13 separate east rift eruptions, two of which persisted 

longer than 4 years. From the first 

return of activity at the lower east 

155°15' 

0 

0 

rift zone in 1955 to the pre-sent, 

almost 30 percent of the land 

surface between the rift zone and 

a 51-kilometer stretch of coastline 

has been covered by lava . 

Geologic mapping and dating 

of volcanic deposits at Kilauea 

form the basis for an astonishing 

statistic-over 90 percent of the 

land surface of Kilauea has been 

covered by lava since the time of 

arrival of the Hawaiians, about 

1,500 years ago. Had the developer been made aware of the entire 

155°00' 

10 MILES 

10 KILOMETERS 

Hazards from lava flows at Kilauea, Hawaii. Relative hazard ranges from 1 (high) to 5 (low). Lava flows 

erupted since [1823i shown in gray; principal subdivisions shown in green. Over 90 percent of the entire 

surface of Kilauea has been covered by lava since Hawaiian occupation began about 1,500 years ago. 

Nearly 30 percent of the land surface in hazard zone 2 south of the east rift zone has been covered since 

1955. Since this map was prepared, an additional area from 6 kilometers west to almost 1.6 kilometers 

east of Kalapana has been covered during 1989-90 activity. Modified from Heliker (1990, p . 24). 

20 Living With Volcanoes 
history of Kilauea's activity, the 

risk of developing the east rift 

zone would have been understood 

to be higher than could be inferred from just considering the 

record of the preceding 111 years. 

The 123-year period of inactivity at Mount St. Helens also 

created a false sense of security 

regarding future activity. However, in this case, a hazard assessment was made in 1978 which 

correctly inferred an end to the 

period of repose and alerted 

people to the possibility of 

renewed activity. 

The 1985 Ruiz eruption offers 

another, much more tragic example of the need to understand the 

entire history of a volcano in assessing hazards. The town of 

Armero, Colombia-buried by 

mudflows triggered by the 1985 

eruption at Nevada del Ruiz-was 

located on a debris fan that was 

overrun by destructive mudflows 

in the year 1595, shortly after the 

arrival of the Spanish colonists, 

and again in 1845, killing hundreds of people in each instance . 

During the ensuing 140-year 

period of inactivity, people forgot 

and the town was rebuilt at the 

same site and grew in population. 

Although a preliminary hazardzone map for Ruiz, completed 

1 month before the November 

1985 eruption, clearly delineated 

Armero as being especially vulnerable to mudflows, emergencyresponse measures taken during 

the eruption were entirely inadequate to save the more than 

23,000 lives lost when the mudflows struck. 

5. 

00' 

4. 

45' 

D 

HAZARD-ZONE MAPS AND VOLCANIC RISK 

High lava-flow 

hazard 

Moderate lava-flow 

hazard 

D 

D 

EXPlANATION 

High pyroclasticflow hazard 

Moderate pyroclasticflow hazard 

High mudflow 

hazard 

74°45' 

Mudflows from November 1985 

eruption of Nevada del Ruiz 

Map showing hazards expected from an eruption of Nevada del Ruiz, 

Colombia. Such a map was prepared by INGEOMINAS (Colombian Institute of 

Geology and Mines) and circulated 1 month prior to the November 13, 1985, 

eruption of Nevada del Ruiz. Map shows danger from mudflows in the valley 

occupied by the town of Armero, Colombia, as well as areas affected by the 

hazards that resulted from this eruption. Circle denotes 20-kilometer limit. 

Remains of Armero, Colombia (in left foreground), surrounded by a sea of 

mud, after having been swept over by a volcanic debris flow roughly 3 

meters deep. Photograph by Dick Janda. 

derstandable information that public officials 

and ordinary citizen s can use in planning for 

volcanic emergen cies. Maps combining informa tion on land classification with the volcanic 

history of an area and the associated hazards 

also form the basis for prudent land-use planning and preparation for the contingency of 

eruptions far into the future . 

Hazard-Zone Maps and Volcanic Risk 21 
Appendix 2 summarizes the status of hazard-related studies for all of the volcanoes listed in Appendix 1. Much work remains to be 

done. Hazards at all volcanoes near populated 

areas have been qualitatively assessed, but 

much of the information must be quantified 

and many of the published hazard assessments 

need updating. 

Lava flow hazard-zone map for the Island of Hawaii. 

Hazard zones range from low (9), associated with the 

dormant Kohala, to high (1 and 2), marking the active 

summit and rift zones of Mauna Loa and Kilauea and the 

areas directly downslope from active vents. Volcano 

boundaries denoted by dashed white lines. Modified 

from Heliker (1990, p . 22) . ..... 

46' 

00' 

122"45' 30' 

10 

1 

"E 

~ C1l 

.c: 

.._ 

0 5 c. 

·;::: 

~ 6 Q) 

ff) 

Ol 7 .s 

ff) 

C1l 8 ~ (.) 

.s: 9 

15 KILOMETERS 

0 10 MILES 

0 

~ 10 KILOMETERS 

122'00' 

Extent of hazards caused by the eruption of Mount 

St. Helens in 1980 c:::J Area affected by blast 

J !J I I I. Area affected by debris avalanche 

Area affected by debris flows 

Area affected by pyroclastic flows 

Areas of potential hazards (Crandell and Mullineaux, 1978) 

Area that could be affected by lava flows, 

pyroclastic flows, debris flows, and floods 

r:::~ Area that could be affected by ash clouds 

associated with pyroclastic flows 

v Area that probably could be affected only by 

· debris flows and floods 

~"'-' Area that probably could be affected only &~ floods 

N 

1 

The actual extent of damage during the May 18, 1980, eruption of Mount St. Helens, Washington , compared with that 

anticipated in the hazard-zone map published two years earlier (Crandell and Mullineaux, 1978). Hachured line 

denotes outline of caldera. 

22 Living With Volcanoes 
THE CHALLENGE OF PREDICTING 

ERUPTIONS 

A primary goal of the Volcano Hazards Program is forecasting and predicting eruptions. 

Several increasingly specific and useful steps 

lead toward prediction (see "How Scientists 

Study Volcanoes"). Initially, when little is 

known about the past history and preemption 

behavior of a volcano, we may only be able to 

give factual information about current unrest; 

for example, that swarms of small earthquakes 

are occurring beneath the volcano, similar to . 

those which have preceded eruptions elsewhere. 

When the average repose period and other 

information regarding a particular volcano's 

eruptions, for example, when the amount of inflation preceding the previous eruption is 

matched by current conditions at that volcano, 

a general forecast can be made that the volcano is "ready" to erupt. The start of microearthquakes or other common eruption precursors 

would lead to an updated forecast-that the 

volcano may erupt soon. 

In the past, forecasts of eruptions were 

based solely on recurring patterns of unrest before eruptions. The occurrence of one particularly diagnostic type of unrest, for example, 

volcanic tremor, might be the basis for a prediction that the volcano would erupt within a 

specified number of hours or days. The appearance of other known eruption precursors 

helped narrow the time window and lent certainty to the prediction. 

We now recognize the need to understand 

why particular patterns and events occur before 

some eruptions, and this need requires a thorough physical understanding of the volcano's 

internal plumbing and the processes associated 

with the generation, transport, storage, and, ultimately, eruption of magma. For example, a 

combination of seismic and geodetic data demonstrates the existence of a complex magma reservoir 2 to 6 kilometers beneath Kilauea's summit from which all eruptions on the volcano 

ultimately originate. Earthquake foci outline the 

area of magma storage, whereas horizontal, vertical, and tilt changes above the reservoir define 

the depth to "centers" of inflation (swelling) or 

deflation. Understanding of this storage system 

has greatly improved the ability to determine 

when Kilauea is fully inflated and ready to 

erupt. Accurate short-term (within days to 

weeks) prediction of Hawaiian eruptions remains elusive, as both Kilauea and Mauna Loa 

may reach a highly inflated state, and wait with 

no further ground deformation or increase in 

seismicity until eruption occurs. Some Kilauea 

rift eruptions are preceded within hours by a 

strong earthquake swarm whose foci migrate toward the point of outbreak, giving a short but 

accurate prediction of this type of activity. Volcano monitoring, combined with study of 

Kilauea's volcanic his tory, yields the information necessary for long-term eruption forecasts. 

Volcano 

Volcano 

surface 

before 

inflation 

Stable 

Kilauea's summit plumbing system, deduced from seismic and ground-deformation data. Volcano profile prior 

to inflation (swelling) is shown by dashed line. Volcano 

surface after inflation is shown as a solid line. Small 

arrows connect dots depicting position of points on the 

ground before and after inflation. All measurements are 

relative to a "stable" point, assumed not to move during 

inflation . Earthquake hypocenters are shown as short 

lines surrounding the magma storage area (red). Large 

arrows denote the direction of magma flow in to the 

storage reservoir, and the direction of strain applied to 

the surrounding rock from movement of magma into the 

reservoir. From Tilling and others (1987, p. 17). 

As with Hawaiian eruptions, the domebuilding eruptions of Mount St. Helens are not 

predictable many months ahead. Prediction of 

dome-building eruptions were made, however, 

within days or weeks, using very simple methods, with relatively little prior knowledge or 

understanding of the volcano's plumbing 

system. 

The Challenge of Predicting Eruptions 23 
PREDicnONS, FORECASTS, AND FACTUAL STATEMENTS 

Successful 

Eruption 

Prediction 

at 

Mount St. Helens, 

Washington 

The terms forecast and 

prediction are often used interchangeably, and both are confused with simple factual statements regarding past occurrence 

of eruptions. Herein, the following distinctions are made: 

As magma moves into the dome in the crater of Mount St. Helens, horizontal 

fault planes form on the crater floor. The edge of the dome moves on the 

crater floor in response to magma pushing outward. The amount of 

movement is measured by the distance between the dome talus and the 

crater floor using nails and a steel tape. Photograph by Terry Leighley. 

A factual statement describes 

current conditions but does not 

anticipate future events. Mauna 

Loa erupted 35 times in the past 

200 years, and the last large 

debris flow from Mount Rainier 

was 500 years ago are two examples of factual statements. The 

accumulation and analysis of such 

factual information form the basis 

for forecasts and predictions. 

A forecast is a comparatively 

imprecise statement of the time, 

place, and, ideally, the nature and 

size of impending activity. For 

example, Mauna Loa is likely to 

erupt at its summit within the 

Accurate predictions are still rare in volcanology, and probabilities associated with 

eruption from a given volcanic system may 

change after an eruption takes place. Often 

volcanic systems are in delicate balance and 

may be considered "ready" to erupt; this determination of readiness allows a mediumrange forecast of increased likelihood of eruption. For many currently dormant but 

potentially active volcanoes, we may only be 

able to give factual information regarding past 

activity without specifying what the future 

holds. For well-studied, historically active volcanoes we can make more specific forecasts of 

future activity. The most accurate predictions 

are in the short-term where either rapid 

ground movements or an earthquake swarm 

directly precedes eruption at the surface. 

24 Living With Volcanoes 

COMMUNICATING RESEARCH 

RESULTS AND HAZARDS 

INFORMATION 

For information derived from the Volcano 

Hazards Program to be of maximum benefit, it 

must be communicated in ways that can be 

easily and directly applied in the reduction of 

volcanic disasters. Such communication can 

take place in two ways: 

• Working directly with local officials responsible for public safety before, during, and 

immediately after volcanic eruptions or damaging hydrologic events. Information on anticipated or actual volcanic hazards is used to 

guide decisions on closing and reopening of 
PREDICTJONS, FORECASTS, AND FACTUAL STATEMENTS 

Prediction issued 

! Eruption 

window 

0 

en 

a: 

w 50 Iw 

:::! 

i= 

z 

w 100 u 

z 

~ 

z 

w 150 CHRISTINA'S :2: 

w THRUST FAULT 

> 

0 

:2: 200 w 

> 

i= 

<( 

...J 

:::> 250 

:2: CHRISTINA 2 :::> 

u THRUST FAULT 

300 

June July August September 

When movement on the faults accelerates, an eruption prediction is issued with a prediction window of 

several days. This window is narrowed as the eruption approaches. Several dome-building eruptions 

were predicted correctly to within 2 days of the actual 

eruption. 

next five years, as determined 

from its rate of reinflation and 

historical eruptive patterns. 

A prediction is a relatively 

precise statement giving the time 

and place of eruption based on 

interpretations and measurements 

of ongoing monitoring results 

and only secondarily on a projection of past history. For example, 

on the basis of accelerated 

movement of thrust faults on the 

crater floor, the next eruption of 

Mount St. Helens will occur in 

the summit crater between March 

17 and March 20 and will be a 

dome-building event. 

Volcanologists strive to make 

accurate predictions, although 

most often a forecast is the most 

reliable statement that can be 

made, given the available data 

and technology. In areas already 

developed or proposed for 

development, all three types of 

information can be used both for 

land-use planning and as a basis 

for developing procedures to 

ensure public safety in anticipation of a volcanic eruption. 

Dacitic magma emerges, adding to the dome. Magma extrusion was often accompanied by explosions that 

partially destroyed the preexisting dome and sent ash over the countryside tens of kilometers from the crater. 

Photograph by Lyn Topinka . 

Predictions, Forcasts, and Factual Statements 25 
roads or recreational areas and evacuating 

people. 

• Providing background information on 

volcanic hazards to local jurisdictions, including planners, developers, public safety officials, and current and potential residents, for 

the dual purpose of supporting informed decisions regarding land use and encouraging adequate planning for future volcanic crises. 

In working directly with public officials, 

the means of communication is generally faceto-face or by telephone . Discussions in anticipation of volcanic activity may result in adoption of hazard-mitigation strategies such as 

warning systems or a hierarchy of alert levels. 

These are activated according to information 

acquired and delivered by the USGS prior to or 

during a volcanic emergency. 

Ongoing communication with public officials is an essential part of the operation of 

each volcano observatory, and it is a task taken 

on by the other USGS offices for restless volcanoes away from the observatory sites. The Hawaiian Volcano Observatory has developed an 

informal and effective communication with the 

National Park Service and Hawaii County Civil 

Defense Agency, the two agencies on the Island of Hawaii responsible for public safety. 

Hawaiian Volcano Observatory scientist briefing Hawaii 

State and County officials on volcanic hazards in Hawaii. 

Photograph by J.D. Griggs. 

The Cascades Volcano Observatory delivers 

warnings of activity at Mount St. Helens in a 

more complex setting, where information on 

volcanic hazards is delivered to many agencies 

at the Federal, State, county, and local levels 

(see Peterson, 1988). This communication also 

has been effective and serves as a model for 

dealing with the many other Cascades volcanoes that have erupted in the not-too-distant 

past and that could erupt again. 

The Alaska Volcano Observatory also has 

to respond to and communicate with a different mix of agencies, including the Federal Aviation Administration (FAA). In recent years, 

Flow of information about Mount St. Helens, Washington , and its hazards. Scientists must interact with other 

authorized groups, including State and County leaders, Jaw-enforcement agencies, land managers, and various public 

agencies and private firms responsible for establishing and enforcing restricted zones and for ordering and 

supervising evacuation when necessary. The U.S. Forest Service, large timber companies, and other State and 

Federal agencies and private companies whose operations and decisions are affected by the volcano depend on this 

information. Other groups, such as the National Weather Service, Federal Aviation Administration, Army Corps of 

Engineers, fish and wildlife agencies, public utilities, and many others also depend on volcanologists for information 

and advice. The news media also receive information from scientists, civil officials, and land managers and convey it 

to the public. 

26 Living With Volcanoes 

SCIENTISTS 

LAND MANAGERS, 

INVOLVED 

AGENCIES, 

PRIVATE 

COMPANIES 

Policies, land use 

I ~=====1 1-----1 NEWS 

c: MEDIA 

interpretations, 

and assessments 

" 0 

0 

(.) 

In formation, I 

.---'-----'----'-----, 

CIVIL 

OFFICIALS 

Informa tion 

I Emergency response regulations 

GENERAL 

PUBLIC 

L---------~ L---,-~ 

Talk to organizations, schools 
DANGER IN THE STRATOSPHERE: AIRCRAFT AND VOLCANIC PLUMES 

During the past 14 years, 

there have been 23 incidents 

involving aircraft that have 

inadvertently encountered eruption plumes. Apart from windshield pitting resulting in loss of 

visibility, the most common result 

is engine damage that occurs 

when volcanic ash enters the jet 

intakes; the volcanic ash melts 

and coats turbine blades, often 

causing the engines to stall. 

Fortunately, in all past cases, 

engines have restarted, but only 

after severe loss of altitude. Most 

recently a Boeing 747 aircraft lost 

power in all four of its engines 

after encountering the plume of 

the explosive eruption of Redoubt 

Volcano on December 15, 1989; it 

glided without power from 8,534 

meters (28,000 feet) until engines 

were restarted at 4,267 meters 

(14,000 ft), only 1,219 meters 

(4,000 feet) above nearby mountain 

peaks. The airliner landed safely 

in Anchorage and no one was 

hurt, but the damage to the aircraft has been estimated to exceed 

$80 million (Steenblik, 1990). 

Personnel from the Volcano 

Hazards Program, particularly 

those at the Alaska Volcano 

Observatory, are working with 

officials of the Federal Aviation 

Administration (FAA) to develop 

automatic early warning systems 

for large ash clouds and to streamline communication for eruptions 

at U.S. volcanoes that might 

impact aircraft. Other countries 

have developed or are developing 

similar procedures, assisted in 

part by the World Organization of 

Volcano Observatories and coordinated through the International 

Civil Aviation Organization. 

25.-------------------------, 

20 (j) 

w 

(j) 

<( 

u 15 LL 

0 

a: 

~ 10-

~ 

:::l 

z 5 

1976 1986 

t\1 .OSH ELDS 

SYSTEM 

DAMAGE 

POWER 

LOSS 

OL-------------------------~ 

DESCRIPTION OF DAMAGE 

Number of aircraft (worldwide) that 

encountered volcanic ash plumes, and 

the type of damage they incurred, 1976 

to 1986. 

tragedies have nearly occurred because of temporary engine failures when commercial jetliners flew into ash plumes. The need to issue 

timely warnings to aircraft has led to development of a system of sensors that detect ash 

clouds and lightning originating from them, as 

well as wind speed and direction. 

est publications on volcanic phenomena. Booklets describing volcano hazards in lay terms, 

some of which are accompanied by hazardzone maps, are available for several volcanic 

areas; the most recent assessments are for 

Mount Shasta (Crandell and Nichols, 1987, 

based on Miller, 1980), the Island of Hawaii 

(Heliker, 1990), and the State of California 

(Miller, 1989). In addition to volcanic hazard 

assessments, specific flood and debris-flow 

hazards have been evaluated at Mount Rainier 

(Scott and others, 1990), Mount St. Helens 

(Swift and Kresch, 1982; Meyer and others, 

1986; Laenen and Orzal, 1987; Major and Scott, 

1988; Glicken and others, 1989), Three Sisters 

(Laenen and others, 1987), and Mount Shasta 

(Osterkamp and others, 1986). General-interest 

publications are available that discuss the volcanic activity of Hawaii (Tilling and others, 

1987), Mount St. Helens (Tilling and others, 

1990), and Redoubt Volcano (Brantley, 1990). 

Other activities, conducted in a noncrisis atmosphere, are media briefings on volcanic procThe USGS's ability to effectively communicate information about potential future volcanic activity has been put to its greatest test at 

Long Valley, where the end result of ongoing 

unrest is difficult to forecast and where negative economic consequences of that information 

were anticipated or experienced. Nonetheless, 

in all of the areas marked by volcanic unrest, 

the goal of the Volcano Hazards Program remains that of keeping the public apprised as to 

the likelihood of eruption and the hazards that 

would be posed. 

The USGS publishes hazard assessments, 

including hazard-zone maps, and general-interDanger in the Stratosphere: Aircraft and Volcanic Plumes 27 
esses and their associated hazards, local forums to discuss the hazards of a specific area, 

or meetings with public officials responsible 

for long-range planning at which USGS 

scientists are invited to provide hazards information. 

Public acceptance of volcano-hazard information as a necessary component of land-use 

planning and decisionmaking is much more 

difficult to achieve than is the coordination of 

response during a volcanic emergency. The 

USGS is empowered only to communicate 

information, not to recommend how that information is to be used. Acting on hazard information provided by the USGS requires that 

public agencies recognize the difference between hazard and risk. Public officials must 

make the often difficult assessment of what is 

an acceptable risk. Many, if not most, areas 

prone to eruption hazards are already developed to the extent that mitigation rather than 

prevention of volcanic destruction is the most 

that can be hoped for. Lives can be saved, 

however, by a combination of a well-informed 

populace, an ongoing effective interaction between scientists and local officials, and timely 

warnings of imminent eruption and associated 

hazards. 

The consequences of imperfect communication or ineffective interaction between scientists 

and public officials can be extremely serious. 

Severe economic hardship and social disruption 

can result from either an actual hazard that is 

not perceived, or from a hazard that is blown 

out of proportion and made to seem worse than 

it is. A dependable communication link-between the scientific personnel responsible for 

making hazards evaluations and the news media-must transmit information in an accurate 

and timely fashion. For example, the Cascades 

Volcano Observatory assigned a public information officer to their staff while volcanic activity 

continued at Mount St. Helens to ensure consistency of information delivered to public officials and the media. 

Ultimately, effective coexistence with volcanoes requires difficult and sometimes controversial compromises to be made between 

the economic pressures to develop land for 

commercial and residential use, and the need 

to set aside areas of highest volcanic hazard 

for wilderness, recreation, or other low-density 

use . Thoughtful land-use planning serves in 

the long run to lessen the risks to the local 

populace in the event of a volcanic eruption. 

HAZARD, RISK, AND ACCEPTABLE RISK 

The terms hazard and risk, 

often used interchangeably, are 

defined herein as follows: 

Hazard: an event or process that 

is potentially destructive. 

Risk: the magnitude of a 

potential loss-of life, 

property, or productive 

capacity-within the area 

subject to hazard(s). 

The threat posed by volcano 

hazards is a function of those 

natural processes and can be 

viewed as constant, whether or 

not lives and property are in 

28 Living With Volcanoes 

jeopardy. Degree of risk, by 

contrast, is directly tied to the 

scale and value of human activity 

in the path of potential hazards. 

Options for controlling volcanic 

hazards are limited: most volcanic 

events cannot be modified by 

humans. However, much can be 

done to minimize volcanic riskby prudent land use, timely 

warnings, and community preparedness. 

Acceptable risk is that which 

individuals, businesses, or governments are willing to accept in 

return for perceived benefits. The 

level of acceptable risk is usually 

defined by local governments, 

taking into account information 

on volcanic hazards and combining it with economic, social, and 

political factors specific to the 

area threatened. In some situations risks will be judged acceptable without special precautions. 

In other situations local governments can take action to reduce 

the risk to acceptable levels, such 

as zoning to control population 

density, or restricting placement 

of critical facilities (for example, 

hospitals) in areas judged to be 

threatened. 
MEETING THE DEMANDS FOR 

GLOBAL VOLCANO HAZARDS 

REDUCTION 

A volcanologist's laboratory is the world's 

volcanoes. Although U.S. volcanoes are an important part of that laboratory, none except 

Kilauea erupts frequently enough for the laboratory to be "open" at all times, and processes 

at Kilauea differ markedly from those of the 

more dangerous, but less active, explosive volcanoes of the Cascades and Alaska. Only 2 to 3 

volcanoes erupt each year in the U.S., most in 

remote locations in Alaska, in contrast to 50 to 

60 worldwide. Participation in investigations 

at volcanoes abroad provides a practical way 

to study more eruptions in the larger laboratory, from which new scientific insights can be 

applied to U.S. volcanoes. In turn, well-studied 

U.S. eruptions such as that at Mount St. Helens 

offer insights that can be applied to similar 

volcanoes worldwide. Cooperative international programs in volcanology also offer the opportunity of sharing information on volcanomonitoring techniques. 

Three examples, one from the U.S., one 

from South America, and one from the Philippines, illustrate the value of a global view of 

volcanism: 

A massive landslide-debris avalanche and 

a laterally directed blast from Mount St. 

Helens in May 1980 thrust those phenomena 

from obscurity to prominence in volcanology. 

Direct visual and instrumental observation of 

the emplacement of that avalanche greatly 

facilitated identification of similar events at 

other volcanoes from study of their deposits. 

Before 1980, only a handful of large volcaniC 

debris avalanches were known; today more 

than 200 have been recognized and more are 

being documented each year. Thus the first 

modern observation of such an event has 

yielded knowledge that can be applied to saving lives around the world. 

The tragedy associated with the November 

1985 eruption of Nevada del Ruiz Volcano, 

Colombia, offered other lessons for the international community. A map, accurately depicting the probable path of a debris flow down 

the river valley whose canyon mouth was directly upstream of the town of Armero, had 

been prepared and was available a month before the disaster (see "Hazard-Zone Maps and 

Volcanic Risk"). After steam explosions began, 

the volcano was monitored by an international 

group of scientists, and local officials issued 

an evacuation warning to the populace of 

Armero less than 2 hours before the debris 

flow arrived (Voight, 1990). For reasons still 

not fully known, the warnings were not translated into effective emergency actions, with the 

result that in that town alone over 21,000 lives 

were lost. The Ruiz tragedy provided a tragic, 

costly lesson regarding the need for more 

effective communication with local citizens 

and public officials prior to an expected eruption. Mount Rainier (see back cover), in the 

U.S. Cascade Range, is a similar volcano and, 

therefore, presents many of the same hazards 

found at Nevada del Ruiz. Mount Rainier is 

high and snow-covered, is built of unstable 

volcanic debris, and has been deeply eroded 

by glaciers; geologic mapping has revealed 

that in the past 10,000 years a number of huge 

debris avalanches and debris flows have run 

down drainages in which many towns between 

Tacoma and Seattle are built. The lessons from 

Colombia, if applied, will help avert a future 

volcanic disaster that may affect the towns and 

cities near Mount Rainier. 

The June 15, 1991, eruption of Mount Pinatubo in the Philippines (Island of Luzon) 

provided the inost recent opportunity for international cooperation. Geologists from the USGS 

and PHIVOLCS (Philippine Institute of Volcanology and Seismology) worked together before 

and during the eruption. Their combined efforts 

produced a result very different from that at 

Nevada del Ruiz-successful prediction of a 

very large eruption combined with an effective 

response to the volcanic emergency. 

ASSISTANCE TO DEVELOPING COUNTRIES 

Most of the world's high-risk volcanoes are 

in developing countries whose growing popuMeeting the Demands for Global Volcano Hazards Reduction 29 
lations are rapidly encroaching on these volcanoes. This encroachment has greatly increased 

the vulnerability of communities and economies to devastation from volcanic eruptions 

and associated hazards. At present, few of 

these nations have the capability to assess volcanic histories to the degree that would allow 

them to accurately assess future potential hazards. The USGS, through the Volcano Hazards 

Program, assumes a professional responsibility 

to assist foreign colleagues who seek to expand 

their own volcano-hazards expertise. Technical 

assistance missions fulfill this responsibility 

and, in return, afford us the opportunity to 

study many more active volcanoes than otherwise possible. U.S. scientists can gain valuable 

experience during overseas volcano crises, and 

they can join foreign colleagues in working to 

find simple, low-cost solutions to problems of 

volcano monitoring and hazard assessment. 

The USGS contributes, through its Volcano 

Crisis Assistance Team (VCA T), to an international Volcano Early Warning and Disaster 

Assistance Program (VDAP) funded by the U.S. 

Agency for International Development's Office 

of Foreign Disaster Assistance (USAID/OFDA) 

and the USGS. VDAP's nominal mission is global but its main work to date has been in Latin 

America, mainly in Ecuador, Colombia, and 

Guatemala . VDAP began as a rapid-response 

team but has evolved to include a substantial 

component of work toward pre-eruption 

preparedness. It has, for example, helped to establish the Observatorio Vulcanologico de Colombia and upgraded capabilities of the Guatemalan Instituto Nacional de Sismologia, 

Vulcanologia, Meteorologia e Hidrologia, and 

the Ecuadorian Instituto Geofisico, Escuela Politecnica Nacional. 

Another USAID /OFDA project, recently 

completed, involved assistance to the Volcanological Survey of Indonesia (VSI). That project 

began as help in upgrading VSI's premier volcano observatory, the Merapi Volcano Observatory; with eruptions at other volcanoes and 

changes in the funding, the project evolved 

into one of general institution-building assistance to VSI and encouraged several specific 

disaster-coordination initiatives. Over the de30 Living With Volcanoes 

cade of the 1980's, VSI made significant 

progress toward a modern observational capability, despite a severe domestic funding crisis. 

Merapi Volcano Observatory, Indonesia. The USGS has 

a cooperative program to train Indonesian scientists and 

technicians in volcano-monitoring techniques. 

Photograph by John Dvorak. 

A third project, just getting underway, is the 

Center for Study of Active Volcanism (CSAV), 

located at the University of Hawaii, Hilo Campus. CSA V is funded by the State of Hawaii to 

train students from developing countries in the 

techniques of volcano monitoring. It draws additional resources from the main branch of the 

University of Hawaii in Honolulu and works 

closely with the USGS Hawaiian Volcano Observatory in both classroom training and assistance 

in teaching field-monitoring techniques. 

Hawaiian Volcano Observatory scientists teaching 

foreign students enrolled in the University of Hawaii's 

(Hilo) Center for Study of Active Volcanoes (CSA V) the 

techniques of recording and locating earthquakes. 

Photograph by Darcy Bevens. 
A VOLCANIC DISASTER AVERTED IN THE PHIUPPINES 

On April 2, 1991, people from 

the village of Patal Pinto, on the 

Philippine Island of Luzon, saw 

small explosions followed by 

steaming and the smell of rotten 

eggs (H2S gas) coming from the 

upper slopes of Mount Pinatubo, a 

dormant volcano whose last 

known eruption was 600 years 

ago. Thus began the unrest that 

within 10 weeks led to one of the 

largest 20th century eruptions. 

The Philippine Institute of 

Volcanology and Seismology 

(PHIVOLCS) immediately installed portable seismometers near 

the mountain and began recording 

several hundred earthquakes a 

day. At the request of PHIVOLCS, 

made through the USAID office in 

Manila, U.S. Geological Survey 

personnel arrived on April 23 . 

Within 2 weeks the team of 

Philippine and American volcanologists had installed a radiotelemetered seismic network 

capable of locating the increasing 

number of earthquakes. They 

began tape measurements across 

fractures opened during the early 

steam explosions, and they later 

installed tiltmeters to detect new 

ground movement. With the help 

of the U.S. Air Force, measurements of the S02 content of gas in 

the steam plumes, now continuously visible at Pinatubo, were 

begun. Between May 13 and May 

28, a 10-fold rise in S02 content 

was measured. All signals indicated that magma was rising within 

the volcano. 

Meanwhile, Philippine and 

American geologists made a 

geological reconnaissance of the 

volcano and established a set of 

alert levels ranging from 1 (lowlevel unrest) to 5 (eruption 

underway). When the alert system 

was completed on May 13, the 

level was set at 2 meaning that 

magma was probably involved in 

the unrest. The geological reconnaissance showed the dominant 

lava products were dacite domes 

near the summit and valley-filling 

Personnel from the U.S. Geological Survey and Phil ippine Instit ute of 

Volcanology and Seismology installing a seismometer to record earthquakes 

at Mount Pinatubo. Photograph by John Ewert. 

pyroclastic flows extending 

radially out from the summit to a 

distance of 10 to15 kilometers. 

Small villages on the volcano's 

northwest slope and part of Clark 

Air Base lay within the potential 

range of pyroclastic flows. Numerous communities, including 

the city of Angeles with a population of 300,000 lay within the 

apron of debris flows extending 

well beyond the volcano. A 

hazard map was prepared and 

distributed to local officials by 

May 23 showing virtually all of 

the hazards subsequently encountered when Pinatubo erupted. 

Seismic activity escalated in 

early June, and on June 5 PHIVOLCS raised the alert level to 

3-eruption possible within 2 

weeks. A small dome extruded on 

the north flank on June 7 accompanied by thousands of small 

earthquakes triggering a level 4 

alert-explosive eruption possible 

within 24 hours. Continuous ash 

emission began, an d 2 days la ter 

PHIVOLCS raised the alert level 

to 5 signifying an eruption had 

begun. Clark Air Base was evacuated on June 10. On June 12, the 

first of several major explosions 

took place, sending airborne ash 

to the west and pyroclastic flows 

down the northwest slope of the 

volcano. Areas potentially impacted by the pyroclastic flows had 

been evacuated in response to the 

level 3 alert. The city of Angeles 

was put on evacuation alert. A 

climactic eruption took place on 

June 15 during passage of a 

typhoon, which had already 

resulted in closure of the International Airport at Manila. The 

typhoon compounded the effects 

of the eruption by generating 

mudflows in addition to ash fall 

and greatly hampering evacua tion 

efforts. By June 16 w hen the 

wea ther cleared, the top of the 

volcano was gone, replaced by a 

A Volcan ic Disaster Averted in the Philippines 31 
A VOLCANIC DISASTER AVERTED IN THE PHIUPPINES 

Timing of events and responses during Mount Pinatubo eruption, Luzon Island, the Philippines 

Date 

(1991) Volcanic activity 

4/2... ........ Small steam explosions; earthquakes 

began. 

4/5 ...... . 

4/ 23 ...... .................................. ......... . 

4/30-5/ 10 ..... 

5/13 ......... Continued earthquakes and steam emission. 

5/23 

5/28 ... ............................. ······················································· 

Monitoring 

PHIVOLCS installed portable 

seismometers. 

USGS joined PHIVOLCS efforts in 

monitoring and hazard assessment. 

PHIVOLCS-USGS radio-telemetered 

seismic network installed. Earthquakes 

located on northwest side of summit. 

Correlation spectrometer (COSPEC) measurements began. 502 emission 

equaled 500 tons/ day. 

Hazard map completed. 

SO:z emission equaled 5,000 tons/ day. 

6/5........... Greatly increased earthquake activity; 

volcanic tremor identified. 

Continued seismic and other monitoring 

provided basis for eruption forecast and 

setting of alert levels. 

6/8............ Dome extruded; further increase in 

number of earthquakes and 

increased volcaruc tremor; beginning of continuous ash 

emission. 

6/9 

6/10 

6/12 First large explosive eruption; 

pyroclastic flows moved down 

northwest valleys. 

6/15 ....... .. Climactic (caldera-forming) eruption. 

Dome collapse; widespread ashfall; 

large pyroclastic flows and 

mudflows. 

Ongoing Continuous ash emission punctuated 

from 6/ 16. by larger ash eruptions all smaller 

than June 15 event; continued small 

pyroclastic flows to northwest and 

mudflows in all directions. 

Continuing PHIVOLCS-USGS monitoring 

2-kilometer-wide caldera, and 

pyroclastic flow deposits had 

largely filled preexisting valleys 

on all sectors of the volcano. Ash 

had fallen over a vast area 

beyond the volcano. The weight 

of the thick blanket of heavy, 

wa ter-saturated ash combined 

with continued felt earthquakes 

resulted in the collapse of many 

buildings in Philippine cities and 

villages as well as on Clark Air 

Base and the more distant Subic 

Bay Naval Base. The ash reached 

thicknesses of 30 centimeters as 

far as 40 kilometers away from 

32 Living With Volcanoes 

the volcano. Following the climactic eruption, continuous ash 

emission at a lower level continues at this writing (July 1991). 

Loss of life in the Pinatubo 

eruption was remarkably low, 

given the size of the eruption350 people died, mostly in buildings that collapsed. The alert 

system put in place by PHIVOLCS 

combined with effective communication among the USGS, PHIVOLCS, local civil defense agencies, and the U.S. Military 

Command prevented a much 

Alert 

level Response 

2 

3 

4 

5 

PHIVOLCS alerted. 

Villages within 10 kilometers of the 

summit were evacuated. 

Alert system in place. 

Villages on northwest slope were evacuated again. 

.. .. Near-total evacuation of Clark Air Base. 

Buildings collapsed from loading by 

water-saturated ash combined with 

felt earthquakes. Manila International 

Airport closed. 

.... Continuing PHIVOLCS-USGS hazard 

evaluation. 

greater human disaster. The 

scientific information necessary to 

guide the alerts was gathered by 

USGS and Philippine geologists 

working side by side, each complementing the others' expertise 

in order to turn potential disaster 

into a responsibly handled volcanic emergency. As an exercise in 

both eruption prediction and 

effective response, the 1991 

Pinatubo eruption provides an 

important model for future 

situations in which dormant 

volcanoes come to life. 
A LOOK TOWARD THE FUTURE 

The 1990's have been designated the International Decade for Natural Disaster Reduction 

(IDNDR). The USGS, as an active participant in 

the IDNDR Program, recognizes several challenges to both our understanding of volcanic 

activity and to our ability to communicate scientific results in a way that can be used by 

communities facing volcanic hazards. We list 

below a representative list of challenges that 

can be met during the 1990's, listed under five 

important elements of the Volcano Hazards 

Program. Tasks designed to meet these challenges are given in Appendix 3. 

Eruption Prediction 

Precursory earthquakes and ground deformation are likely at any volcano about to become active. Establishment and monitoring of 

base line seismic and geodetic networks at all 

volcanoes that present a potential risk to populated areas are essential to early detection of 

volcanic unrest and potential eruption. The 

technology for monitoring volcanic unrest is 

rapidly changing. It is possible now to telemeter data from seismometers to a central facility, 

where earthquake hypocenters can be located 

automatically within minutes after they occur. 

It will soon be possible to also telemeter data 

on ground movements via Global Positioning 

Satellite (GPS) geodesy. We anticipate that 

within two decades GPS instrumentation will 

replace conventional geodetic techniques of 

volcano monitoring. This will make possible 

the early detection of volcanic unrest wherever 

it occurs, allowing time to augment geodetic 

and seismic monitoring with other techniques, 

and adequate time to take proper measures to 

reduce volcanic risk, should the unrest 'culminate in eruption. 

Volcano Hazard Assessment 

Hazard assessments at several U.S. volcanoes, using data from many sources, need to be 

completed or updated. Integration and analysis 

of the wide variety of data that are used in 

volcano hazard assessment will be greatly facilitated by the emerging technology of Geographic Information Systems (GIS). Using GIS, 

the entire spectrum of maps covering different 

types of hazards in a given volcanic area could 

be displayed and printed when needed. To be 

effective, GIS requires both accurate and up-todate geologic, geochemical, geophysical, and 

hydrologic data. In turn, fundamental geologic 

and hydrologic studies in volcanic regions 

must be expanded and updated. Another developing technology is computer modeling of 

the paths of lava flows, debris flows, or debris 

avalanches. For such modeling it is essential to 

have accurately digitized topographic maps of 

volcanoes. The results of flow-path modeling 

will allow precise forecasts of the area and 

timing of impact for a volcanic event if the 

source area, for example, volcanic vent or potential landslide scarp, is known. Computer 

modeling also holds promise for predicting 

downwind transport rates, altitudes, and dispersion of ash clouds. 

Research in Volcano Processes 

Of all the various types of eruptive activity, explosive eruptions pose the greatest threat 

to life and property. Large-scale explosive 

activity involves interaction of liquid magma or 

very hot rock with the surrounding groundwater system. At present we have an inadequate understanding of the processes associated with magma-water interactions. It is possible now to address these problems by 

combining increasingly sophi~ticated geophysical techniques with measurements from wells 

and advanced ground-water modeling. 

Large-scale debris avalanches (often accompanied by debris flows and floods) have potential to cause the greatest loss of life near many 

of the world's volcanoes. Modeling of ground 

water and magma fluid pressures, stress distributions in volcanic cones, and susceptibility to 

seismic destabilization will allow us to (1) recognize sectors of volcanic cones that are potentially unstable, (2) identify seismic, geodetic, or 

other precursory signs to catastrophic failures, 

and (3) predict the timing, ultimate size, or runA Look Toward the Future 33 
out distance of an avalanche if failure is anticipated. Our understanding of the flow dynamics 

of large debris flows and related sedimentcharged flood waves is also far from complete. 

Quantitative characterization of these, on a par 

with our understanding of normal floods, is 

necessary for accurate prediction of arrival 

times and inundation depths in downstream 

areas. Theoretical and experimental data collection is now being planned as a cooperative research project between the USGS (at CVO) and 

the U.S. Forest Service. 

Another promising area of inquiry is the 

relation of certain seismic signals, for example, 

harmonic tremor, to the movement of magma 

toward the surface-specifically, to the release 

of dissolved gases during magma transport 

and to the boiling of ground water. Greater 

understanding of the behavior of magma underground will contribute to more accurate 

forecasting of eruptions and to discrimination 

of geophysical signals that are actual precursors to eruption from those that merely signify 

temporary volcanic unrest. 

Effective Communication 

During the 1980's we gained valuable experience in working with public officials and 

local communities faced with volcanic eruptions in Hawaii (from Mauna Loa and 

Kilauea), Washington and Oregon (from Mount 

St. Helens), and Alaska (from Mount Augustine and Redoubt Volcano), and with a threat 

of volcanic eruption at Long Valley, California. 

We also learned lessons from various volcanic 

crises and disasters elsewhere in the world. A 

major challenge of the 1990's is to develop 

emergency response plans that can be quickly 

put in place in any area that shows signs of 

volcanic unrest. Experience indicates that 

graduated levels of alert and response are best. 

The implementation of such plans will require 

close coordination and cooperation with local 

officials responsible for public safety and with 

the affected community. 

34 Living With Volcanoes 

Two USGS publications released within a 

month after the October 17, 1989, Lorna Prieta 

earthquake in California summarize the lessons 

learned and deliver an important message regarding the likelihood of more damaging 

earthquakes in California within the next 30 

years (Plafker and Galloway, 1989; Ward and 

Page, 1989). The Lorna Prieta earthquake also 

was the catalyst to prepare "The Next Big 

Earthquake in the Bay Area May Come Sooner 

than You Think. Are You Prepared?," a magazine supplement in nontechnical English, Spanish, and Chinese that was distributed to over 

2.8 million San Francisco Bay Area residents a 

year later. Just as earthquakes continue to happen in California, so will some of the presently 

dormant volcanoes in the U.S. reawaken and 

erupt. The Volcano Hazards Program strives to 

anticipate these eruptions and to provide a 

firm basis for community preparedness before 

a volcanic crisis strikes. 

Working in the World Laboratory 

At the beginning of the International Decade of Natural Disaster Reduction, a number 

of volcanoes around the world were nominated 

for intensified collaborative study. U.S. volcanoes are Mount Rainier, Mauna Loa, and Long 

Valley Caldera. The first was an obvious selection for the magnitude of the threat to densely 

populated areas west of the volcano. The second was chosen because it is relatively easy to 

study, much is already known to guide further 

study, and like the work done at Kilauea, we 

expect to be able to develop and test volcanomonitoring techniques on Mauna Loa for use 

on other volcanoes where access is more difficult. The third is a caldera that is now showing 

unrest. It is a type of volcano with the potential for widespread destruction, but it is also a 

type for which very little is known in terms of 

eruption precursors. We anticipate that international collaboration will yield far greater insights into the nature of volcanic processes and 

the hazards they pose than would the effort of 

any single nation. 
EPILOG 

Even with anticipated technological advances in the 1990's, the work 

of the Volcano Hazards Program will continue to be people-intensive. 

Geologic and hydrologic fieldwork necessary for hazards mapping, and 

the interpretation of monitoring data cannot be done by sophisticated instruments or computer software alone, nor can a GIS printout substitute 

for human interaction and judgment during a volcanic crisis. We also 

recognize the need to develop simple, low-cost, and rugged ("low-tech") 

instruments and techniques that complement the increasingly sophisticated and expensive "high-tech" approaches. 

Volcanoes with their eruptions and other related hazards have long 

been regarded in this country as exotic phenomena found only in remote 

corners of the world. In 1980 when Mount St. Helens demonstrated a 

wide spectrum of nature's fury that perception changed dramatically. 

Now that we have (1) a much better understanding of hazardous processes at volcanoes, (2) new advances in monitoring and computer technology, (3) the fresh awareness of what volcanoes can do in the minds of 

people around the world, and (4) the IDNDR with its opportunities for 

scientific exchange, the 1990's are ripe for significant progress in reaching the goals of the Volcano Hazards Program. The USGS is ready to 

meet the ongoing challenge of understanding volcanic hazards to mitigate and, when possible, prevent volcanic disasters. 

Epilog 35 
PHOTOGLOSSARY OF VOLCANIC HAZARDS 

Ash-laden eruption plume from 

Mount St. Helens rising into the . 

stratosphere and moving eastward 

with the prevailing winds (July 22, 

1980). Photograph by Mike Doukas. 

Ash falling in Yakima, Washington, on 

May 18, 1980, following the eruption of 

Mount St. Helens. Photograph courtesy 

of Yakima Herald-Republic. Used with 

permission. 

36 Living With Volcanoes 

The following photographs illustrate 

different kinds of eruptive activity and the 

associated hazards for selected volcanic areas 

within the United States 

Pyroclastic fallout (ash fall or tephra fall). Volcanic ash (material less than 2 millimeters in diameter) or tephra (material greater 

than 2 millimeters in diameter) is formed when magma is finely 

fragmented by vesiculation or when previously solidified rocks 

are shattered by the explosion of ground water into steam. Ash 

falls are deposited beneath an eruption column and for many 

kilometers downwind; the ash fall becomes finer grained with 

increasing distance from the volcano. Vigorous eruption plumes 

can carry the finest ash into the stratosphere, where strong 

winds distribute it over many thousands of kilometers. Even a 

small ash fall poses a serious nuisance to people, crops, machinery, and computers. When thick or wet, it can cause roofs to 

collapse. Windborne ash is a serious threat to aircraft. 
Channeled aa lava flow from Mauna Loa, March 1984. 

Photograph by Toni Duggan. 

Lava dome of Novarupta, Katmai National Monument, 

Alaska. Photograph by Gene lwatsubo. 

Lava flows. Streams of molten rock that either effuse quietly from a vent or are fed by lava fountains. 

Fluid basalt flows can move at velocities from 15 to as high as 50 kilometers per hour on steep slopes and 

travel up to tens of kilometers from their source. Viscous andesite flows move only a few kilometers per 

hour and rarely extend more than 8 kilometers from their vent. Lava flows destroy everything in their path, 

but most move slowly enough that people can escape. Lava domes. Lava (usually dacite or rhyolite) that is 

too sticky to flow far from its vent forms steep-sided mounds called lava domes. 

Destruction of the National Park Service Wahaula Visitor Center on June 22, 1989, 

by pahoehoe lava from Kilauea. Photograph by J.D. Griggs. 

Photoglossary of Volcanic Hazards 37 
PHOTOGLOSSARY OF VOLCANIC HAZARDS 

Volcanic gases. The most 

common gases associated with 

active volcanoes are water 

vapor, carbon dioxide, sulfur 

dioxide, hydrogen sulfide, 

hydrogen, helium, carbon 

monoxide, and hydrochloric 

acid. Lesser amounts of hydrofluoric acid, nitrogen, argon, 

and other compounds are 

commonly associated with 

active volcanoes as well. 

Volcanic gases rarely reach 

popu lated areas in lethal 

concentrations, although sulfur 

dioxide can react with the 

atmosphere downwind and fall 

as acid rain to cause corrosion 

and a host of other effects. 

People with respiratory or heart 

diseases are especially susceptible to volcanic gases (fum e). 

Carbon dioxide is heavier than 

air and tends to collect in 

depressions, where it can occur 

in lethal concentrations and 

cause suffocation. On occasion, 

toxic concentrations of fluorine 

from hydrofluoric acid have 

been adsorbed onto ash and 

ingested by livestock or leached 

into domestic water supplies. 

38 Living With Volcanoes 

Volcanic gas plume from Puu Oo cone, Kilauea east rift zo ne, April 1985. 

Ph otograph by J .D. Griggs . 

Broccoli plants wi lted by volcanic fume from the ong oing 

eruption at Kilauea. Ph otog raph by J.D. Griggs. 
Pyroclastic flows and pyroclastic surges. Mixtures of hot 

rock fragments and gases can 

sweep away from their source 

vents at hurricane velocity. 

Pyroclastic flows are dense and 

most are confined to valleys 

around a volcano; the largest ones 

can travel tens or even hundreds 

of kilometers beyond a volcano. 

Pyroclastic surges are turb-ulent, 

low-density variants of pyroclastic flows. Some unusually rapid 

pyroclastic flows or surges 

originate from laterally directed 

explosions from a vent. Because 

of their high speed and high 

temperature, pyroclastic flows 

and surges kill or destroy virtual-

! y all that is in their path. Pyroclastic flow moving downslope at M o unt St. Helens, A ugust 

1980. Photograph by Rick Hob/itt. 

The town of St. Pierre, 

Martinique, following the 

eruption of Mont Pelt§e in 

1902. Pyroclastic flows 

completely destroyed the 

town of 65,000 people. 

Photographer unknown. 

Photoglossary of Volca nic Hazards 39 
PHOTOGLOSSARY OF VOLCANIC HAZARDS 

Volcanic landslide that 

marked the beginning of the 

Mount St. Helens eruption, May 

18, 1980. The landslide itself, 

obscured by the eruption 

plume, is represented by the 

missing sector of the volcano, 

which slid away just prior to 

the explosion producing the 

eruption plume. Photograph 

courtesy of Keith Ronnholm. 

Used with permission. 

Volcanic landslides. Gravity-driven slides, often rapid, of a mass of rock and soil that can occur in all 

sizes, from those involving a small amount of loose debris on the surface of a volcano to massive failures of 

the entire summit and (or) the flanks of a volcano. Volcanic landslides need not be associated with eruptions; heavy rainfall or a large earthquake can trigger landslides on steep volcanic slopes. Landslides that 

have evolved into a chaotic tumbling flow are termed debris avalanches. 

Debris avalanche deposit in North 

Fork Toutle River valley following 

the May 18, 1980, eruption of Mount 

St. Helens (in the distance). Valley is 

approximately 2.4 kilometers wide. 

Photograph by Lyn Topinka. 

40 Living With Volcanoes 
Volcanic debris flows 

(mudflows or lahars). Flowing 

mixture of water-saturated 

debris, intermediate between a 

debris avalanche and a water 

flood, typically moves at speeds 

of several tens of miles per hour 

on steep slopes, slowing to less 

than 10 mi per hour on gentle 

slopes. Debris flows can travel 

tens of miles down valley and 

devastate distant unsuspecting 

communities, as in Colombia 

during the 1985 eruption of 

Nevada del Ruiz. 

Waning stage of May 18, 1980, volcanic debris flow in Toutle River valley. 

Woody debris covers banks and fluid surface; mud slurry contains nearly 

two-thirds rock fragments by volume. Photograph by Don Swanson. 

Caldera. Large depression 

commonly formed by collapse 

of the ground following explosive eruption of a large body of 

stored magma . Calderas at 

Yellowstone and Long Valley 

are associated with eruption of 

silicic magma as pyroclastic 

flows that covered large areas 

around and within the caldera. 

Kilauea caldera, by contrast, is 

thought to be associated with 

draining of basaltic magma 

from beneath Kilauea's summit. 

The caldera now filled by 

Oregon's Crater Lake was 

produced by an eruption that 

destroyed a volcano the size of 

Mount St. Helens and sent 

volcanic ash as far east as 

Nebraska. 

Aerial view of Crater Lake showing depression (caldera) left by destruction of 

ancestral Mount Mazama and subsequent collapse. Photograph by Roland 

Emetaz, U.S. Forest Service. Used with permission. 

Photoglossary of Volcanic Hazards 41 
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Moore, J.G., Clague, D.A., Holcomb, R.F., Lipman, 

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Prodigious submarine landslides on the Hawaiian ridge: Journal of Geophysical Research, v. 

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Newhall, C.G., and Dzurisin, Daniel, 1988, Historical unrest at large calderas of the world, 2 vols.: 

U.S. Geological Survey Bulletin 1855, 1109 p. 

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Peterson, D.W., 1988, Volcanic hazards and public 

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U.S. Geological Survey Water-Resources InvestiReferences Cited 43 
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Survey pamphlet, 16 p. 
Appendix 1. Active and potentially active volcanoes in the United States 

Volcano 

Eruption 

type(s) 

Number of Latest activity (in 

eruptions in the years before present 

past 200 years or year(s) A.D.) Remarks 

HAWAII 

Loihi . . . . . . . . . . . . . . . . . . Lava. . . . . . . . . . . Not known. . . . . . . Not known . . . . . . . . . . Submarine volcano; seismically active; youngest 

lava less than 1 ,000 years old. 

Kilauea . . . . . . . . . . . . . . . Lava, most 

common; 

ash, rare. 

47 . . . . . . . . . . . . . . . Ongoing from 

1983 

Explosive eruption at Kilauea summit in 1790 

killed approximately 80 Hawaiian warriors. 

Eruptions presenting lava-flow hazard to coastal 

areas: 4 in the 19th century; 5 in the 20th century. 

Mauna Loa............ Lava........... 30 ............... 1984 . . . . . . . . . . . . . . . . Eruptions presenting lava-flow hazard to coastal 

areas: 8 in the 19th century; 8 in the 20th century. 

Hualalai............... Lava, ash . . . . . . 1 ................. 1800-01 . . . . . . . . . . . . High hazard due to unusually fluid lava. 

Mauna Kea . . . . . . . . . . . Lava, ash . . . . . . 0 . . . . . . . . . . . . . . . . . 4,000 years ago . . . . . Frequency of activity before latest eruption is 

estimated to be about 300 years. 

Kohala................ Lava, ash . . . . . . 0 ................. 120,000 years ago... Volcanic cycle may not be completed, but eruption 

probability is low. 

Haleakala . . . . . . . . . . . . . Lava, ash . . . . . . 1 . . . . . . . . . . . . . . . . . 1790 . . . . . . . . . . . . . . . . In last stage of Hawaiian volcanic cycle. Expected 

recurrence rate estimated to be about 200-600 

years. 

ALASKA 

Eastern Alaska 

Wrangell . . . . . . . . . . . . . . Ash . . . . . . . . . . . . 1?. . . . . . . . . . . . . . . . 1902? . . . . . . . . . . . . . . . Emission of gases and vapors from vents (fumarolic 

activity). 

Cook Inlet 

Mount Hayes . . . . . . . . . Ash . . . . . . . . . . . . 0 . . . . . . . . . . . . . . . . . 450? 

Mount Spurr . . . . . . . . . . Ash............ 1 ................. 1953 

Redoubt Volcano . . . . . Ash, dome..... 4 ................. Ongoing............. Eruption began December 1989. 

Iliamna Volcano . . . . . . Ash . . . . . . . . . . . . ? . . . . . . . . . . . . . . . . . ? 

Augustine Volcano . . . Ash, dome . . . . . 5 . . . . . . . . . . . . . . . . . 1986 

Alaska Peninsula 

Katmai Group . . . . . . . . . Ash, lava 

Mount Mageik ..... 

Mount Martin ..... . 

Novarupta ......... . 

Trident Volcano .... 

Mount UgashikMount Peulik 

(Ukinrek Maars). 

4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1946 

7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1990 

1 . . . . . . . . . . . . . . . . . 1912 . . . . . . . . . . . . . . . . The world's largest 20th century eruption. 

1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1964 

Ash . . . . . . . . . . . . 1 . . . . . . . . . . . . . . . . . 1977 . . . . . . . . . . . . . . . . Ukinrek Maars formed 1.5 kilometers south of 

Becharof Lake, 12 kilometers from Peulik. 

Appendix 1 45 
Appendix 1. Active and potentially active volcanoes in the United States-Continued 

Volcano 

Y antami Volcano1

-

Mount Chiginagak. 

Eruption 

type(s) 

Number of Latest activity (in 

eruptions in the years before present 

past 200 years or year(s) A.D.) 

Alaska Peninsula-Continued 

Ash............ 2 ................. 1971 

Aniakchak Crater . . . . . Ash, dome..... 1 (or 2?) . . . . . . . . . 1931 

Mount Veniaminof. . . . Lava, ash . . . . . . 7 . . . . . . . . . . . . . . . . . 1983-84 

Remarks 

Mount EmmonsPavlof Volcano. 

Ash, lava . . . . . . 30 . . . . . . . . . . . . . . . 1987 . . . . . . . . . . . . . . . . Pavlof is most frequently active volcano in Alaska. 

Mount Dutton . . . . . . . . . Ash, lava . . . . . . 0 . . . . . . . . . . . . . . . . . ? ................... . 

Aleutian Islands 

Kiska Volcano . . . . . . . . Ash, lava . . . . . . 7 ................. 1990 . . . . . . . . . . . . . . . . Steam and ash emission. 

Little Sitkin Volcano1 Ash, lava? 

Mount Cerberus 

(Semisopochnoi). 

Mount Gareloi ........ 

Tanaga Volcano ....... 

Kanaga Volcano ...... 

Great Sitkin Volcano 

Kasatochi Island ...... 

Ash, lava? 

Ash, lava . ..... 

Lava, ash ...... 

Lava ........... 

Ash, dome ..... 

? ............... 

1?................ 1900? 

1 . . . . . . . . . . . . . . . . . 1987 . . . . . . . . . . . . . . . . Possibly from Sugarloaf, satellitic vent on south 

flank. 

6 ................. 1987 

1 . ................ 1914 

2 ................. 1933 

6 ................. 1974 

1 . ................ 1828 

Korovin Volcano Ash . . . . . . . . . . . . 7 . . . . . . . . . . . . . . . . . 19 51? 

Pyre Peak 

(Seguam). 

Ash, lava . . . . . . 5 . . . . . . . . . . . . . . . . . 1977 . . . . . . . . . . . . . . . . Eight lava fountains, as high as 90 meters. 

Amukta Volcano 1 • . • . . Ash, lava . . . . . . 3 . . . . . . . . . . . . . . . . . 1987 

Yunaska Island . . . . . . . Ash............ 2 ................. 1937 . . . . . . . . . . . . . . . . Minor ash emission. 

Carlisle Volcano . . . . . . ? . . . . . . . . . . . . . . . 1 ................. 1987 . . . . . . . . . . . . . . . . Probable small steam and ash eruption, possibly 

from Cleveland. 

Mount Cleveland . . . . . Ash, lava . . . . . . 10 . . . . . . . . . . . . . . . 1987 . . . . . . . . . . . . . . . . 1945 eruption resulted in only known fatality from 

Alaska volcanism. 

Kagamil Volcano ..... ? ............... 1 . ................ 1929 

Mount V sevidof ....... Ash ............ 1 ................. 1957 

Okmok Caldera ....... Ash, lava . ..... 11 . .............. 1988 

Bogoslof Volcano 1 ••.. Ash, dome ..... 6 ................. 1951 

Makushin Volcano .... Ash ............ 7 ................. 1980 

46 Living With Volcanoes 
Appendix 1. Active and potentially active volcanoes in the United States-Continued 

Volcano 

Akutan Peak .......... 

Westdahl Peak ....... 

Fisher Dome 

Shishaldin 

Volcano. 

Eruption 

type(s) 

Ash, lava ..... 

Ash, lava . .... 

Ash ........... 

Ash, lava ..... 

Number of Latest activity (in 

eruptions in the years before present 

past 200 years or year(s) A.D.) Remarks 

Aleutian Islands-Continued 

21 ............... 1988 

2 ................ 1978 

0 ................ 1830 

About 18 ........ 1987 

Isanotski Peaks . . . . . . . Ash, lava . . . . . 0 . . . . . . . . . . . . . . . . 1845 

CASCADE and COAST RANGES 

Washington 

Mount Baker . . . . . . . . . Ash, lava . . . . . 1? . . . . . . . . . . . . . . . 1870 . . . . . . . . . . . . . . . Increased heat output and minor melting of summit 

glacier in 1975; some debris flows not related to 

eruption. History of extensive pyroclastic flows. 

Glacier Peak . . . . . . . . . . Ash . . . . . . . . . . . More than 1? . . . . Before 1800 ....... . 

Mount Rainier . . . . . . . . Ash, lava . . . . . 1? . . . . . . . . . . . . . . . 1882 (?) . . . . . . . . . . . . History of massive debris avalanches and debris 

flows. Occasional very shallow seismicity. 

Mount Adams . . . . . . . . Lava, ash . . . . . 0 . . . . . . . . . . . . . . . . More than 3,500 

years ago. 

Debris flows are the most recent events. 

Mount St. Helens . . . . . Ash, dome, 

lava. 

2-3 . . . . . . . . . . . . . 1980-present . . . . . . . Continuing intermittent volcanic activity. 

Oregon 

Mount Hood.......... Ash, dome.... 2?............... 1865 . . . . . . . . . . . . . . . Occasional seismic swarms. 

Mount Jefferson...... Ash, lava ..... 

Three Sisters . . . . . . . . . Ash, lava ..... 

Crater Lake . . . . . . . . . . Ash, lava, 

dome. 

Newberry Crater . . . . . Ash, lava ..... 

0 . . . . . . . . . . . . . . . . More than 50,000 Debris flows in 1934, 1955; young basaltic flows 

years ago. in nearby area. 

0 . . . . . . . . . . . . . . . . 950? . . . . . . . . . . . . . . . . Debris flows in this century. 

0 . . . . . . . . . . . . . . . . 4,000 years ago . . . . Largest known eruption from Cascade Range 

volcano. Catastrophic, caldera-forming eruption 

7,000 years ago; post-caldera lava and domes. 

0 . . . . . . . . . . . . . . . . 600 . . . . . . . . . . . . . . . . Latest eruption was obsidian flow. 

California 

Medicine Lake . . . . . . . Ash, lava . . . . . 0 . . . . . . . . . . . . . . . . 1065 . . . . . . . . . . . . . . . Latest eruption formed Glass Mountain. 

Mount Shasta......... Ash, dome.... 1 . . . . . . . . . . . . . . . . 1786? . . . . . . . . . . . . . . Debris flows in this century. 

Lassen Peak .. .. .. .. .. Ash, dome .. .. 1 . . .. .. .. .. .. . . . . 1914-1917 .. .. .. .. . Lateral blast occurred in last eruption. 

Clear Lake2 . . . . . . . . . . Lava, ash . . . . . 0 . . . . . . . . . . . . . . . . Not known . . . . . . . . . Geothermal energy and long-period (volcanic) 

seismicity suggest "active" status. 

Appendix 1 47 
Appendix 1. Active and potentially active volcanoes in the United States-Continued 

Volcano 

Long Valley 

Caldera. 

Coso Peak ........... . 

San Francisco 

Field. 

Bandera Field 

(McCarty's Flow). 

Craters of the Moon, 

Idaho. 

Yellowstone Caldera, 

Wyoming, Montana, 

and Idaho. 

Eruption 

type(s) 

Ash, dome, 

ashflow. 

Lava, ash, 

dome. 

Number of Latest activity (in 

eruptions in the years before present 

past 200 years or year(s) A.D.) 

CONTINENTAL INTERIOR 

California 

3?............... About 1400 ........ 

0 .. .. .. .. .. .. .. .. About 40,000 years 

ago. 

Arizona 

Remarks 

Youngest activity represented by nearly 

simultaneous eruptions of rhyolite at several of 

the lnyo craters; currently restless, shown by 

seismicity and ground deformation. 

Geothermal energy production and seismic 

activity suggest "active" status. 

Lava . . . . . . . . . . 2 . . . . . . . . . . . . . . . . 1065-1180 . . . . . . . . . Sunset Crater; disrupted Anasazi settlements. 

New Mexico 

Lava . . . . . . . . . . 1 . . . . . . . . . . . . . . . . About 1000 . . . . . . . . Most voluminous lava within past 1000 years. 

Idaho, Montana, and Wyoming 

Lava.......... About 1 . . . . . . . . . 2,100 years ago . . . . Youngest activity in the Snake River Plain. 

Ashflow . . . . . . 0 . . . . . . . . . . . . . . . . 70,000 years ago . . . Numerous hydrothermal explosions, geysers, 

geothermal activity; currently restless, shown 

by seismicity and ground deformation. 

1Informal name, not officially recognized by the Board on Geographic Names. 

2California Coast Ranges. 

48 Living With Volcanoes 
Appendix 2. Status of hazard evaluation for volcanoes in the United States 

[Volcanoes included on the same map are grouped together] 

Monitoring 

Geologic Petrologic Hydrologic Hazard 

Volcano map study study Seismic Geodetic Gas Other1 assessment 

HAWAII 

Loihi Yes Yes No Yes No Little No No 

(preliminary) 

Kilauea Yes Yes Incomplete2 Yes Yes Yes Yes Yes 

MaunaLoa Yes Yes No Yes Yes Yes3 Yes3 Yes 

Hualalai Yes Yes No Yes Yes3 No No Yes 

MaunaKea Yes Yes No Yes Yes3 No No Yes 

Kohala Yes Yes No Yes No No No Yes 

Haleakala Yes(needs Yes No Yes No No No Yes 

revision). 

ALASKA 

Eastern Alaska 

Wrangell No Incomplete4 Incomplete4 No No No No No 

White River No No No No No No No No 

Edgecumbe Yes Yes No No No No No Preliminary 

Cook Inlet 

Hayes No No No No No No No No 

Spurr In progress Yes Yes Yes No No No In progress 

Redoubt In progress In progress In progress Yes Yes Yes No In press 

Iliamna In progress In progress No Yes No No No No 

Augustine In progress Yes No Yes Yes3 Yes3 No Preliminary 

Alaska Peninsula 

Ugashik-Peulik In progress In progress No No No No No No 

Yantarni-Chiginagak No No No No No No No No 

Aniakchak In progress In progress No No No No No No 

Black Peak In progress No No No No No No No 

Veniaminof In progress In progress No No No No No No 

Dana In progress No No No No No No No 

Emmons Lake-Pavlof In progress In progress No Yes No No No No 

Dutton In progress In progress No Yes No No No No 

Appendix 2 49 
Appendix 2. Status of hazard evaluation for volcanoes in the United States-Continued 

Monitoring 

Geologic Petrologic Hydrologic Hazard 

Volcano map study study Seismic Geodetic Gas Other1 assessment 

Alaska Peninsula-Continued 

Katmai group (includes Yes5 Novarupta No Yes Novarupta No No No 

Martin, Mageik, only only3 

Novarupta, Trident, 

Katmai) 

Aleutian Islands 

Reconnaissance geologic maps exist for about one-third of the Aleutian volcanoes, but these lack the details necessary for deciphering 

eruptive history. Only a few petrologic studies, hydrologic studies, and monitoring studies have been made of Aleutian volcanoes. 

CASCADE and COAST RANGES 

Washington 

Mount Baker Outdated Incomplete Incomplete Yes Yes3 Yes3 No Preliminary6 

Glacier Peak Outdated Incomplete Incomplete Poor No No No Preliminaif 

Mount Rainier Outdated No Yes Yes Yes3 No No In progress 

Mount Adams In progress In progress Incomplete Poor No No No Partial 

Mount St. Helens In progress Incomplete Yes Yes Yes Yes No Needs updating 

Oregon 

Mount Hood Outdated Incomplete Incomplete Yes Yes3 Yes3 No Preliminaif 

Mount Jefferson In progress In progress Incomplete Yes No No No No 

Three Sisters Partial Incomplete Incomplete Yes Yes3' 7 No No In progress8 

Newberry Crater Yes In progress Incomplete Yes Yes3 No No No 

Crater Lake In progress In progress Incomplete Yes Yes3 No No No 

California 

Medicine Lake In progress9 Yes Incomplete Yes Yes3 No No In progress10 

Mount Shasta In progress In progress Incomplete Yes Yes3 Yes3 No Preliminaif 

Lassen Peak In progress In progress Incomplete Yes Yes Yes No Preliminaif 

Clear Lake Yes Yes Incomplete Yes No No No No 

CONTINENTAL INTERIOR 

California 

Long Valley Yes Yes Yes Yes Yes Yes No Preliminary 

Coso Field Yes Yes Yes Yes No No No No 

50 Living With Volcanoes 
Appendix 2. Status of hazard evaluation for volcanoes in the United States-Continued 

Monitoring 

Geologic Petrologic Hydrologic 

Volcano map study study Seismic Geodetic Gas Other1 

Arizona 

San Francisco Field Yes Yes No Yes No No No 

New Mexico 

Bandera Field Yes Yes No No No No No 

Montana, Idaho, and Wyoming 

Craters of the Moon Yes Yes Incomplete Yes No No No 

Yellowstone, Montana Yes Yes Incomplete Yes Yes Yes No 

Idaho, Wyoming. 

1 Electrical geophysics, magnetics, and gravity. 

2

Extensive mapping of the local water table and fresh water-seawater interface using resistivity soundings and 

geophysical logs from one deep drill hole. 

3Limited coverage or infrequent remeasurement. 

Hazard 

assessment 

No 

No 

Preliminary 

No 

4Field studies have been completed, but the volcano has not been thoroughly and systematically studied using modem 

techniques. 

5No mapping of individual volcanoes. 

6Hydrologic component of assessment not yet complete. 

7No monitoring of North Sister, Middle Sister, or Mount Bachelor. 

8Geologic component of assessment only. 

9Geologic map (covering approximately 10 percent of the volcano) of Lava Beds National Monument published. 

10Both geologic and hydrologic components need updating. 

Appendix 2 51 
Appendix 3. Tasks for the 1990's and visions for the 21st century 

ELEMENTl. 

Eruption prediction 

Priority activities in 

the 1990's are: 

52 Living With Volcanoes 

TASKS FOR THE 1990'S 

Future tasks and activities of the Volcano Hazards Program can 

be described in five elements, which also serve as the framework of 

the accompanying text. 

1. Eruption prediction 

2. Volcanic hazard assessment 

3. Research in volcanic process 

4. Effective communication 

5. Working in the world laboratory 

The first four elements are carried forward from the program's 

previous long-range plan (Bailey and others, 1983); the fifth is an explicit recognition that the program exists in a shrinking world in 

which international sharing is of great mutual benefit. 

Below, we describe each element and the principal activities that 

are presently planned for the 1990's. Many activities are a continuation of those in the 1980's; others are new and reflect advances in our 

understanding of the behavior of volcanoes. Specific activities will 

be adjusted as new eruptions and new insights demand. 

Eruption prediction is fast becoming a reality. Virtually every 

eruption has measurable precursors and the recognition and interpretation of those precursors is improving yearly. Volcanoes that erupt 

frequently offer many chances for testing predictions; those which 

erupt infrequently (and often dangerously) are the subject of the 

greatest uncertainties and are the most challenging. It is also important to recognize and predict the end of eruptions, so activities and 

business in communities around volcanoes can return to normal. 

• Continue intensive monitoring of the Nation's most restless volcanoes and volcanic areas, including Kilauea, Mauna Loa, Mount 

St. Helens, Mount Rainier, Long Valley Caldera, Yellowstone 

Caldera, Augustine, and Redoubt Volcano. Monitors on the west 

flank of Mauna Loa will be upgraded. At other hazardous volcanoes, continuous seismic monitoring will be combined with periodic remeasurement of ground-deformation, gas, and other baseline parameters to anticipate renewed activity. 

• Use new digital seismic instrumentation to monitor preeruption 

signals such as volcanic tremor. These will supplement, not replace, conventional seismic networks. 
ELEMENT 2. 

Volcanic hazard 

assessment 

Priority activities in 

the 1990's include: 

• Extend seismic coverage to more volcanoes, especially in Alaska. 

Networks will be installed around the more active and accessible 

volcanoes (for example, active volcanoes on the Alaska Peninsula). Simpler, event-counting, satellite-telemetered seismometers 

will be installed on active but remote volcanoes, so that eruptions and ash hazard to aircraft can be anticipated. 

• Expand use of Global Positioning System monitoring on U.S. volcanoes to obtain real-time records of ground movement. 

• Develop new geophysical and geochemical monitors whose data 

can be collected and cross-correlated continuously. 

• Seismic and ground-deformation monitoring of those volcano 

flanks thought likely to collapse and (or) generate large earthquakes, for example, Kilauea, Mauna Loa, and Mount Rainier. 

Long-range planning for land use and emergency response complement eruption prediction and are important tools in volcanic risk 

reduction. Volcanic hazard assessments by the USGS are the primary 

scientific basis for this planning by land managers and emergency response officials. 

• Integrate geologic mapping, detailed stratigraphic information, 

petrologic studies (especially of petrologic change during eruptions and from one eruption to the next), hydrologic factors, historical and current unrest, and interpretative models of how each 

volcano works into a new generation of comprehensive volcanic 

hazard assessments. 

• Work toward greater quantification of volcanic hazard assessments. 

• Increase use of Geographic Information System (GIS) technology, 

both for analysis and dissemination of information. 

• Conduct additional studies of explosive eruptions at Hawaiian 

volcanoes, including field studies of their deposits, the role of 

ground water, and theoretical studies of magma-ground water 

interaction. 

• Compile detailed geologic maps of Mount Hood, Mount St. 

Helens, Mount Rainier, and Mount Baker. 

• Complete geologic maps and hazard assessments for individual 

volcanic centers of the Cook Inlet (Spurr, Redoubt, Iliamna, and 

Augustine) and selected volcanoes of the Alaska Peninsula and 

the Wrangell Mountains. 

Appendix 3 53 
ELEMENT 3. 

Research in volcanic 

processes 

Priority projects in 

the 1990's are: 

ELEMENT4. 

Effective 

communication 

54 Living With Volcanoes 

• Evaluate of the impacts of volcanic eruptions and degassing on 

human health and agricultural productivity, using observations 

from a worldwide sample of volcanoes. 

• Study how volcanic ash threatens jet aircraft and passenger safety and determine how that threat can be minimized. 

Several of these activities complement, and will be complemented 

by, work under the Volcano Emissions activity of the U.S. Global 

Change Research Program. 

State-of-the-art eruption predictions and long-range hazard assessments require a solid understanding of processes before, during, 

and following eruptions. With such an understanding, we can anticipate specific changes, such as imminent ascent of magma or incorporation of stream-bank sediment into debris flows, rather than wait to 

observe and recognize them. 

• Study the occurrence and significance of long-period earthquakes and volcanic tremor, which are promising parameters for 

eruption prediction. 

• Study the accumulation and release of gases from magma, including the rapid release of gases during explosive eruptions. 

• Explore relation between regional tectonic strain and volcanic 

eruptions. 

• Model in detail the ground-water system at one or more selected 

volcanoes to improve our understanding of how ground water 

influences eruptions and what effect it has on weakening the 

volcanic edifice. 

• Model, both theoretically and experimentally, how hot rock interacts with snow and ice, and how glacial outburst floods originate at volcanoes. 

• Model how volcanic debris flows develop, flow, and abate. 

Even the most reliable scientific information about volcanoes and 

their impacts will be of little use unless it is presented in terms that 

are useful to planners, emergency management officials, businesses, 

and citizens. Outreach measures to ensure public safety from volcanic eruptions begin long before an emergency develops, especially 

with volcanic hazard assessments and public education, and continue 

through periods of volcanic unrest and eruptions with forecasts, predictions, and real-time tracking of eruptive activity. 
Priority activities in 

the 1990's are: 

ELEMENT 5. 

Working in the 

world laboratory 

Priority international 

activities during the 

1990's are: 

• Integrate volcanic hazards information into Geographic Information Systems used by State and local planners. 

• Expand public education programs, using a variety of media including video, general-interest publications, and school curriculum materials. Conduct workshops for public officials, teachers, 

news media, and citizens. 

• Work with the FAA, NOAA, and the airline industry to develop 

an effective system for detecting and tracking ash plumes in real 

time, initially in the Cook Inlet, but extend the system to other 

parts of the U.S. as soon as possible. 

International collaboration offers opportunities to learn more 

about hazardous volcanism than we can learn in the U.S. alone and to 

share what we learn with others. Many more eruptions occur abroad 

than in the U.S., and many advances in volcanology are being made 

abroad. Increasingly, scientific advances and successful volcanic crisis management will involve collaboration between scientists from 

different countries, sharing observation techniques and interpretations. 

• Participate in multidisciplinary, multinational hazard-mitigation 

projects on selected "Decade Volcanoes," as part of the International Decade for Natural Disaster Reduction. Three Decade 

Volcanoes are within the U.S., where U.S. volcanologists will be 

joined by foreign colleagues; an additional 10 to 20 Decade Volcanoes are located in other countries, where U.S. volcanologists 

will join by invitation if the activity contributes to program 

goals. 

• Assist developing nations faced with volcanic crises that seek 

USGS expertise. The program seeks to continue the Volcanic Disaster and Early-Warning Assistance Program (VDAP), in cooperation with USAID's Office of Foreign Disaster Assistance. Initially, activities will be focused in Latin America, as now; later, 

some activities may be added in Southeast Asia and Africa. 

• Conduct investigations on foreign volcanoes or in foreign laboratories to address specific topics of import to U.S. hazards mitigation, for example, how snow and ice are melted by pyroclastic 

flows to form debris flows, or processes of caldera unrest. New 

collaboration is already planned with Japan and the USSR. Such 

collaboration is likely with Italy and other countries. 

• Participate in global information exchanges among volcanologists. This will most easily be accomplished by working with 

the World Organization of Volcano Observatories and with the 

Smithsonian's Global Volcanism Project. 

Appendix 3 55 
56 Living With Volcanoes 

VISIONS FOR THE 21ST CENTURY 

Today's dream is tomorrow's reality, and the Volcano Hazards 

Program aims to overcome a number of technical and scientific limitations by the 21st century. Examples of what might be accomplished 

by early in the next century include: 

• Place monitoring instruments on every potentially active U.S. 

volcano 

• Set up a real-time data base of unrest at U.S. volcanoes, and link 

it to a comparable data base for regional seismicity. 

• Set up continuous GPS monitoring of deformation at many volcanoes. 

• Use geostationary satellites to conduct, multispectral, high-resolution surveillance of U.S. volcanoes. 

• Use artificial intelligence (AI) to analyze volcanic unrest and improve the logical rigor of eruption predictions. 

• Build experimental apparatuses that will reproduce eruptions of 

laboratory-produced magma to test the influence of various factors (such as composition, temperature, and gas content) on style 

of eruption. 

• Conduct experiments to test models of the initiation and hydraulics of debris flows. 

• Monitor continuously, in real time, sediment movement in 

streams draining active volcanoes. 

• Map and monitor, in real time, ground water in volcanoes. 

• Identify and monitor, in real time, potentially unstable sectors of 

volcanic edifices. 

• Link data networks among the USGS volcano observatories and 

link volcanologists around the world using networked telecommunications. 

• Conduct a lively continuing education program that effectively 

transfers information about volcanoes from scientists to public 

officials, using new communications technology. 

• Place interactive, user-friendly GIS workstations in county and 

State emergency response offices, on which public officials can 

request information about various hazards over various time 

frames, overlay this information on risks, and see the effects of 

various mitigation options. 

Judging from the pace of progress in the 1980's and the increasing challenges from technology and world population growth, the 

1990's and the 21st century will be a challenging and busy time for 

the Volcano Hazards Program. 
Appendix 4. Participants in the workshop "Volcano Hazards Program Directions for the 1990's," held 

November 13-15, 1989, at the Cascades Volcano Observatory, Vancouver, Washington 

Norman G. Banks 

Steven R. Brantley 

Jane M. Buchanan-Banks 

Philip J. Carpenter 

Thomas J. Casadevall 

Bernard A. Chouet 

Robert L. Christiansen 

Ernest D. Cobb 

John E. Costa 

Paul T. Delaney 

Michael P. Doukas 

Daniel Dzurisin 

Elliot T. En do 

John W. Ewert 

Gary L. Gallino 

Name 

Robert Decker 

David Pieri 

Tom Simkin 

Barry Voight 

U. S. Geological Survey 

Cynthia A. Gardner Thomas L. Murray 

Terrence M. Gerlach Christopher G. Newhall 

David H. Harlow Garald G. Parker 

Edward W. Hildreth Thomas C. Pierson 

David P. Hill Kevin M. Scott 

Richard M. Iverson William E. Scott 

Richard J. Janda Michael L. Sorey 

Malcolm J. Johnston Cinthia M. Stine 

Peter W. Lipman Donald A. Swanson 

John P. Lockwood Robert I. Tilling 

JonJ. Major Randall G. Updike 

Jeffrey N. Marso Richard B. Waitt 

Kenneth A. McGee JosephS. Walder 

C. Daniel Miller Craig S. Weaver 

Thomas P. Miller Edward W. Wolfe 

Non-USGS 

Organization 

University of Hawaii, Hilo 

Jet Propulsion Laboratory, Pasadena 

Smithsonian Institution, Washington 

Pennsylvania State University 

Appendix 4 57 

Back cover: Snow-covered Mount Rainier, rising behind Tacoma, Washington. Because of its historical activity and 

proximity to major population centers, Mount Rainier is targeted for intensified study during the International Decade 

of Natural Disaster Reduction (IDNDR). Photograph by Lyn Topinka.