U.S. GEOLOGICAL SURVEY—REDUCING THE RISK FROM VOLCANO HAZARDS Can Another Great Volcanic Eruption Happen in Alaska? he largest eruption on Earth Tthis 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 grow- ing 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. On the afternoon of June 6, 1912, an Today, the blocky lava dome of Novarupta sits in the ash-and-debris-fi lled volcanic crater, more than a mile wide, created by a cataclysmic 1912 ominous cloud rose into the sky above Mount volcanic eruption that rained ash over southern Alaska, western Canada, Katmai on the Alaska Peninsula. The cloud and the Pacifi c Northwest. Snow-capped Mount Mageik, another potentially explosive volcano in Katmai National quickly reached an altitude of 20 miles, and Park, can be seen in the background. Inset shows a resident of the devastated village of Kodiak, 100 miles southeast of within 4 hours, ash from a huge volcanic erup- Novarupta, standing in deep drifts of ash shortly after the June 1912 eruption (courtesy National Geographic Society). tion began to fall on the village of Kodiak, 100 miles to the southeast. By the end of the erup- numbers of the plants and small animals they was devastated, especially from 1915 to 1919, tion on June 9th, the ash cloud, now thousands lived on were wiped out. Millions of dead birds because of the starvation and failure of many of miles across, shrouded southern Alaska and that had been blinded and coated by volcanic ash adult fi sh to spawn in ash-choked streams. western Canada, and sulfurous ash was falling littered the ground. Aquatic organisms, such as In 1916, a National Geographic Society on Vancouver, British Columbia, and Seattle, mussels, insect larvae, and kelp, as well as the expedition led by Robert Griggs visited Mount Washington. The next day the cloud passed fi sh that fed upon them, perished in ash-choked Katmai and found a 2-mile-wide crater where over Virginia, and by June 17th it reached shallow water. Alaska’s salmon-fi shing industry its summit had been before 1912. Nearby, the Algeria in Africa. The ash fall from the cataclysmic 1912 erup- During the 3 days of the eruption, dark- . "EAUFORT3EA tion of Novarupta dwarfs that produced by ness and suffocating conditions caused by recent eruptions of Augustine, Redoubt, and falling ash and sulfur dioxide gas immobi- Spurr Volcanoes. Old-timers in Alaska can lized the population of Kodiak. Sore eyes !,!3+! recall dozens of eruptions from these and and respiratory distress were rampant, and other Alaskan volcanoes. Within 500 miles of Anchorage, several volcanoes (brown water became undrinkable. Radio com- 04!!3( /6!25 munications were totally disrupted, and &AIRBANKS . triangles) have exploded in Novarupta-scale eruptions in the past 4,000 years. Beyond the with visibility near zero, ships couldn’t $AWSON "ERING3EA *AN areas shown here, ash fall from these recent dock. Roofs in Kodiak collapsed under the (AYES eruptions of Augustine, Redoubt, and Spurr weight of more than a foot of ash, build- T 3PURR 3EP #HURCHILL Volcanoes was negligible, but ultrafi ne dust ings were wrecked by ash avalanches that 2EDOUBT2EDOUBT !NCHORAGE and sulfurous aerosols were held aloft and rushed down from nearby hillslopes, and !UGUSTINE #!.!$! transported farther by high-altitude winds. *A other structures burned after being struck +AGUYAK N *UNEAU Even though relatively small, the volcanic .OVARUPTA ash clouds from these eruptions still resulted by lightning from the ash cloud. +ODIAK Similar conditions prevailed elsewhere in !NIAKCHAK in airport closures and damage to many jet 6ENIAMINOF "LACK ./6!2504!!3(+ETCHIKAN southern Alaska, and several villages were 0EAK aircraft. Because of the size and frequency abandoned forever. Animal and plant life of eruptions and prevailing winds, Alaskan was decimated by ash and acid rain from 0ACIFIC/CEAN volcanoes present a greater threat to avia- tion on the west coast of the United States the eruption. Bears and other large animals 6ANCOUVER than do the volcanoes of the Cascade Range were blinded by ash and starved when large ./6!2504!!3(&!,, in the Pacifi c Northwest. #/-0!2%$4/4(!4&2/- -),%3 3EATTLE 2%#%.4!,!3+!.%2504)/.3 U.S. Department of the Interior +),/-%4%23 7!3( USGS Fact Sheet 075–98 U.S. Geological Survey 1998 -),%3 !NCHORAGE T +),/-%4%23 LE N In the 1950’s, volcanologists discovered that the 3PURR ) would be overwhelmed by great Alaskan eruption of 1912 was not from Mount K RM 2EDOUBT O people with eye, throat, and IUK ! E O Katmai, as previously thought, but from a new vent )L K ,AK X # KNE 3AVONOSKIVILLAGE lung damage. Building ventila- .A at Novarupta. The eruption removed so much molten ABANDONEDIN !,!3+! tion systems would have to rock (magma) from beneath Mount Katmai, however, ERUPTION be closed to outside air. Ash that a cubic mile of Katmai’s summit collapsed to form SKA !2%! !UGUSTINE LA entering computers, bankcard a 2-mile-wide volcanic depression, called a caldera, /&-!0 ! F O machines, and other electronic which now holds a lake 800 feet deep. Nearby Trident +!4-!) LF Volcano issued several lava fl ows (red) and small ash .!4g, U . equipment would cause them 6 ' A 0!2+ clouds during the decade beginning in 1953. There is LLE to break down. Automobile, Y O F no historical record of eruptions at Mageik, Martin, 4 +/$)!+ snowmobile, and boat engines EN +ODIAK 4 )3,!.$ and Griggs Volcanoes, but their vigorous sulfur-rich HO -T'RIGGS US would also be damaged. Air- AN fumaroles (volcanic gas vents) suggest that they might D 3 ports, including Anchorage, which handles the M O erupt in the near future. K E #RATER .OVARUPTA S ,AKE largest amount of air cargo of any airport in the 4RIDENT United States and is a refueling stop for many expedition discovered a newly formed lava 6OLCANO -T+ATMAI trans-Pacifi c fl ights, would be closed until -T -T-AGEIK dome they called “Novarupta” and huge fl ows -ARTIN runways could be cleared of ash. To avoid the of volcanic ash fi lling what they named the . ash cloud, aircraft would have to be diverted “Valley of Ten Thousand Smokes” for the around most of Alaska, Canada, and the North- numerous plumes of steam rising from the ern United States, seriously disrupting national still-hot ground. Griggs’ descriptions of these -),%3 and international commerce. spectacular features helped persuade President +),/-%4%23 Even years later, volcanic ash deposited Woodrow Wilson to create Katmai National 6OLCANICVENTS EACHASITEOFPAST +ATMAIVILLAGE within 200 miles of the site of the eruption ERUPTIONS ABANDONEDIN Monument (now National Park) in 1918. ERUPTION would be remobilized by windstorms and 6OLCANICASHANDPUMICEFROM X In the 1950’s, volcanologists discovered that .OVARUPTAERUPTIONREMOBLIZEDBY blown high into the atmosphere, renewing the STREAMSARROWSSHOWDIRECTIONOFFLOW the 1912 eruption was actually from Novar- ,ANDSLIDESDEBRISAVALANCHES OF hazards for people and machinery. Fish and +ATMAI"AY upta, not Mount Katmai. Novarupta’s eruption VOLCANICMATERIAL wildlife would be devastated as they were after had removed so much molten rock (magma) the 1912 eruption, wreaking prolonged havoc from beneath Mount Katmai that it caused a nearby coastal communities. Explosive erup- on Alaska’s now large and economically impor- cubic mile of Katmai’s summit to collapse. tions can also produce large earthquakes. In tant fi shing and tourism industries. The chance of another Novarupta-scale 1912, when Novarupta exploded and Mount Promptly restoring normal life would de- eruption occurring in any given year is small, Katmai collapsed, 14 quakes of magnitude 6 pend heavily on community spirit, civic organi- but such cataclysmic volcanic events are certain to 7 rocked the region, and countless smaller zation, and pre-eruption planning. By working to happen again in Alaska. Within 500 miles shocks occurred. As with Novarupta, however, closely with local authorities, air carriers, and of Anchorage, volcanologists have identifi ed the greatest hazard posed by eruptions of most the public, the Alaska Volcano Observatory at least seven deposits of volcanic ash younger Alaskan volcanoes is airborne ash—even (AVO), a cooperative effort of the U.S. Geo- than 4,000 years that approach or exceed the minor amounts of ash can cause the engines logical Survey (USGS), the University of volume of ash ejected by Novarupta in 1912, of jet aircraft to suddenly fail in fl ight, create Alaska Fairbanks Geophysical Institute, and the including a thick layer of ash erupted from health problems, close roads and airports, dis- Alaska Division of Geological and Geophysical Hayes Volcano, only 90 miles northwest of An- rupt utilities, and contaminate water supplies Surveys, is helping to minimize the effects of chorage. Of the numerous volcanoes scattered for hundreds of miles downwind. volcanic eruptions on Alaskan communities. across southern Alaska, at least 10 are capable In 1912, Alaska was very sparsely populat- AVO provides volcano hazards assessments of exploding in a 1912-scale eruption. ed, and there were few airplanes. Now, nearly and closely monitors the State’s volcanoes for When volcanoes erupt explosively, high- three-quarters of a million people live in the any signs of unrest, so that it can issue timely speed fl ows of hot ash (pyroclastic fl ows) State, and aircraft carrying more than 15,000 warnings of impending eruptions. and landslides can devastate areas 10 or more passengers and millions of dollars in cargo pass In addition to active participation in AVO, miles away, and huge mudfl ows of volcanic near Alaska’s more than 40 historically active the ongoing work of the USGS Volcano Haz- ash and debris (lahars) can inundate valleys volcanoes each day.