alaska - U.S. GEOLOGICAL SURVEYREDUCING THE RISK FROM...

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300 +),/-%4%25 0 600 -),%5 0 !,!3+! (AYES #HURCHILL 6ENIAMINOF !NIAKCHAK #/-0!2%$ 4/ 4(!4 &2/- 2%#%.4 !,!3+!. %2504)/.3 +AGUYAK $AWSON *UNEAU +ETCHIKAN +ODIAK !NCHORAGE "ERING 3EA !UGUSTINE 2EDOUBT 2EDOUBT 3PURR #!.!$! *AN 1997 3E PT1998 "LACK 0EAK 6ANCOUVER 3EATTLE 7!3( *A N 1 9 : ; .OVARUPTA "EAUFORT 3EA 0ACIFIC /CEAN ./6!2504! !3( 1917 ./6!2504! !3( 1917 . 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 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 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. 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 volcanic eruption that rained ash over southern Alaska, western Canada, and the Pacifi c 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 erup- tion 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 ultrafi ne 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 avia- tion on the west coast of the United States than do the volcanoes of the Cascade Range in the Pacifi c Northwest. On the afternoon of June 6, 1912, an
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alaska - U.S. GEOLOGICAL SURVEYREDUCING THE RISK FROM...

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