0 300 KILOMETERS

0 200 MILES

Fairbanks

ALASKA

Hayes

Churchill

Veniaminof

Aniakchak

NOVARUPTA ASH FALL

COMPARED TO THAT FROM

RECENT ALASKAN ERUPTIONS

Kaguyak

Dawson

Juneau

Ketchikan

Kodiak

Anchorage

Bering Sea

Augustine

Redoubt Redoubt 

Spurr

CANADA

Jan

1990

Sept 1992

Black

Peak

Vancouver 

Seattle

WASH

Novarupta Jan 1976

Beaufort Sea

Pacific Ocean NOVARUPTA ASH 1912

NOVARUPTA ASH 1912

N

U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet-075-98

1998

Can Another Great Volcanic Eruption Happen in Alaska?

U.S. GEOLOGICAL SURVEY—REDUCING THE RISK FROM VOLCANO HAZARDS

T

US SG

he largest eruption on Earth

this century occurred at

Novarupta Volcano, Alaska, in

June 1912, creating Katmai

Caldera and the Valley of Ten

Thousand Smokes. Volcanic ash

(more than from all other historical eruptions in Alaska combined) devastated areas

hundreds of miles away. Such

massive eruptions will occur

again in southern Alaska,

threatening its rapidly growing

population. To protect the public, U.S. Geological Survey

(USGS) and other scientists

with the Alaska Volcano Observatory closely monitor the

State’s many active volcanoes.

Today, the blocky lava dome of Novarupta sits in the ash-and-debris-filled

volcanic crater, more than a mile wide, created by a cataclysmic 1912

volcanic eruption that rained ash over southern Alaska, western Canada,

and the Pacific Northwest. Snow-capped Mount Mageik, another potentially explosive volcano in Katmai National Park,

can be seen in the background. Inset shows a resident of the devastated village of Kodiak, 100 miles southeast of

Novarupta, standing in deep drifts of ash shortly after the June 1912 eruption (courtesy National Geographic Society).

The ash fall from the cataclysmic 1912 eruption of Novarupta dwarfs that produced by recent eruptions of Augustine, Redoubt, and

Spurr Volcanoes. Old-timers in Alaska can recall dozens of eruptions from these and other

Alaskan volcanoes. Within 500 miles of Anchorage, several volcanoes (brown triangles)

have exploded in Novarupta-scale eruptions

in the past 4,000 years. Beyond the areas

shown here, ash fall from these recent eruptions of Augustine, Redoubt, and Spurr Volcanoes was negligible, but ultrafine dust and sulfurous aerosols were held aloft and

transported farther by high-altitude winds.

Even though relatively small, the volcanic ash

clouds from these eruptions still resulted in

airport closures and damage to many jet aircraft. Because of the size and frequency of

eruptions and prevailing winds, Alaskan volcanoes present a greater threat to aviation on

the west coast of the United States than do

the volcanoes of the Cascade Range in the

Pacific Northwest.

On the afternoon of June 6, 1912, an ominous cloud rose into the sky above Mount

Katmai on the Alaska Peninsula. The cloud

quickly reached an altitude of 20 miles, and

within 4 hours, ash from a huge volcanic eruption began to fall on the village of Kodiak, 100

miles to the southeast. By the end of the eruption on June 9th, the ash cloud, now thousands

of miles across, shrouded southern Alaska and

western Canada, and sulfurous ash was falling

on Vancouver, British Columbia, and Seattle,

when large numbers of the plants and small

animals they lived on were wiped out. Millions

of dead birds that had been blinded and coated

by volcanic ash littered the ground. Aquatic organisms, such as mussels, insect larvae, and

kelp, as well as the fish that fed upon them,

perished in ash-choked shallow water. Alaska’s

salmon-fishing industry was devastated, especially from 1915 to 1919, because of the starvation and failure of many adult fish to spawn in

ash-choked streams.

In 1916, a National Geographic Society expedition led by Robert Griggs visited Mount

Katmai and found a 2-mile-wide crater where

Washington. The next day the cloud passed

over Virginia, and by June 17th it reached

Algeria in Africa.

During the 3 days of the eruption, darkness and suffocating conditions caused by

falling ash and sulfur dioxide gas immobilized the population of Kodiak. Sore eyes

and respiratory distress were rampant, and

water became undrinkable. Radio communications were totally disrupted, and with

visibility near zero, ships couldn’t dock.

Roofs in Kodiak collapsed under the

weight of more than a foot of ash, buildings

were wrecked by ash avalanches that

rushed down from nearby hillslopes, and

other structures burned after being struck

by lightning from the ash cloud.

Similar conditions prevailed elsewhere

in southern Alaska, and several villages

were abandoned forever. Animal and plant

life was decimated by ash and acid rain

from the eruption. Bears and other large

animals were blinded by ash and starved
CUBIC MILES OF MAGMA

3

.003 .005 .05

.1 1.2

Spurr

1992

Redoubt

1989–90

Augustine

1976

Mount 

St. Helens

(Washington)

1980

Pinatubo

(Philippines)

1991

ALASKAN 

VOLCANOES Novarupta

1912

Graphic design by

Susan Mayfield, Judy Fierstein, and Sara Boore

Federal Aviation Administration

National Geographic Society

National Park Service

National Weather Service

Judy Fierstein, Wes Hildreth,

James W. Hendley II, and Peter H. Stauffer

For more information contact:

Alaska Volcano Observatory (907) 786-7497

4200 University Drive

Anchorage, AK 99508

http://volcanoes.usgs.gov/

See also Volcanic Ash–Danger to Aircraft

in the North Pacific (USGS Fact Sheet 030-97)

The 1912 eruption of Novarupta was

the largest on Earth this century. Explosive eruptions are best compared

by recalculating the amount of

erupted volcanic materials, such as

ash and pumice, in terms of the original volume of molten rock (magma)

released (shown diagramatically by

orange spheres). On this basis, the 3

cubic miles of magma erupted from

Novarupta in 1912 was 600 times

greater than the total erupted by Redoubt Volcano in 1989–90 and 30

times greater than the volume of

magma released in the 1980 eruption

of Mount St. Helens, which killed 57

people and caused damage exceeding 1 billion dollars. Even the 1991

eruption of Mount Pinatubo, the second largest in the world this century,

was less than half the size of

Novarupta’s eruption.

its summit had been before 1912. Nearby, the

expedition discovered a newly formed lava

dome they called “Novarupta” and huge flows

of volcanic ash filling what they named the

“Valley of Ten Thousand Smokes” for the numerous plumes of steam rising from the stillhot ground. Griggs’ descriptions of these spectacular features helped persuade President

Woodrow Wilson to create Katmai National

Monument (now National Park) in 1918.

In the 1950’s, volcanologists discovered that

the 1912 eruption was actually from Novarupta,

not Mount Katmai. Novarupta’s eruption had removed so much molten rock (magma) from beneath Mount Katmai that it caused a cubic mile

of Katmai’s summit to collapse.

The chance of another Novarupta-scale

eruption occurring in any given year is small,

but such cataclysmic volcanic events are certain to happen again in Alaska. Within 500

miles of Anchorage, volcanologists have identified at least seven deposits of volcanic ash

younger than 4,000 years that approach or exceed the volume of ash ejected by Novarupta in

1912, including a thick layer of ash erupted

from Hayes Volcano, only 90 miles northwest

of Anchorage. Of the numerous volcanoes scattered across southern Alaska, at least 10 are

capable of exploding in a 1912-scale eruption.

When volcanoes erupt explosively, highspeed flows of hot ash (pyroclastic flows) and

landslides can devastate areas 10 or more miles

away, and huge mudflows of volcanic ash and

debris (lahars) can inundate valleys more than

50 miles downstream. Around island volcanoes, like Augustine in Cook Inlet, pyroclastic

flows and landslides can generate giant ocean

waves (tsunamis) that threaten nearby coastal

communities. Explosive eruptions can also produce large earthquakes. In 1912, when

Novarupta exploded and Mount Katmai collapsed, 14 quakes of magnitude 6 to 7 rocked

the region, and countless smaller shocks occurred. As with Novarupta, however, the greatest hazard posed by eruptions of most Alaskan

volcanoes is airborne ash—even minor

amounts of ash can cause the engines of jet aircraft to suddenly fail in flight, create health problems, close roads and airports, disrupt utilities,

and contaminate water supplies for hundreds of

miles downwind.

In 1912, Alaska was very sparsely populated, and there were few airplanes. Now,

nearly three-quarters of a million people live in

the State, and aircraft carrying more than

15,000 passengers and millions of dollars in

cargo pass near Alaska’s more than 40 historically active volcanoes each day.

The heavy ash fall produced by a Novaruptascale eruption occurring today in southern

Alaska would bring the State’s economy to a

standstill and kill or injure hundreds. Clinics

would be overwhelmed by

people with eye, throat, and

lung damage. Building ventilation systems would have to be

closed to outside air. Ash entering computers, bankcard machines, and other electronic

equipment would cause them

to break down. Automobile,

snowmobile, and boat engines

would also be damaged. AirAlaska Division of Geological and

Geophysical Surveys

Geophysical Institute, University of

Alaska Fairbanks

COOPERATING ORGANIZATIONS

In the 1950’s, volcanologists discovered that the great

Alaskan eruption of 1912 was not from Mount Katmai, as

previously thought, but from a new vent at Novarupta.

The eruption removed so much molten rock (magma)

from beneath Mount Katmai, however, that a cubic mile

of Katmai’s summit collapsed to form a 2-mile-wide volcanic depression, called a caldera, which now holds a

lake 800 feet deep. Nearby Trident Volcano issued several lava flows (red) and small ash clouds during the decade beginning in 1953. There is no historical record of

eruptions at Mageik, Martin, and Griggs Volcanoes, but

their vigorous sulfur-rich fumaroles (volcanic gas vents)

suggest that they might erupt in the near future. ports, including Anchorage, which handles the

largest amount of air cargo of any airport in the

United States and is a refueling stop for many

trans-Pacific flights, would be closed until runways could be cleared of ash. To avoid the ash

cloud, aircraft would have to be diverted

around most of Alaska, Canada, and the Northern United States, seriously disrupting national

and international commerce.

Even years later, volcanic ash deposited

within 200 miles of the site of the eruption

would be remobilized by windstorms and

blown high into the atmosphere, renewing the

hazards for people and machinery. Fish and

wildlife would be devastated as they were after

the 1912 eruption, wreaking prolonged havoc

on Alaska’s now large and economically important fishing and tourism industries.

Promptly restoring normal life would depend heavily on community spirit, civic organization, and pre-eruption planning. By working

closely with local authorities, air carriers, and

the public, the Alaska Volcano Observatory

(AVO), a cooperative effort of the U.S. Geological Survey (USGS), the University of

Alaska Fairbanks Geophysical Institute, and

the Alaska Division of Geological and Geophysical Surveys, is helping to minimize the effects of volcanic eruptions on Alaskan communities. AVO provides volcano hazards

assessments and closely monitors the State’s

volcanoes for any signs of unrest, so that it can

issue timely warnings of impending eruptions.

In addition to active participation in AVO,

the ongoing work of the USGS Volcano Hazards Program in other volcanically active regions of the United States, including Hawaii,

California, Arizona, Wyoming, and the Pacific

Northwest, is helping to better protect people’s

lives and property from volcano hazards.

Savonoski village 

(abandoned in

1912 eruption)

0 5 MILES

0 10 KILOMETERS

x

x

N

Mt Griggs

Mt Katmai

Trident Volcano

 Mt

 Martin Mt Mageik

Katmai village 

(abandoned in 

1912 eruption)

Volcanic vents, each a site of past 

eruptions

Volcanic ash and pumice from 1912 

Novarupta eruption remoblized by 

streams (arrows show direction of flow)

Landslides (debris avalanches) of 

volcanic material Katmai Bay

Valley of Ten Thousan

Novarupta

d Smo es k

Crater 

Lake

Iliuk Arm

(Naknek Lake)

Anchorage

ALASKA

Kodiak

N

Cook

Inlet

Gulf of Alaska

100 MILES

AREA

OF MAP

Augustine

Redoubt

Spurr

KODIAK

ISLAND

0

0 100 KILOMETERS

KATMAI 

NAT'L

PARK