Events of the 1912 eruption of Novarupta/Katmai
By John Scott, University of Alaska Fairbanks geology student

100 years ago, Alaska was the site of the world's largest explosive volcanic eruption of the 20th century. During 60 hours, over 3 cubic miles (about 13.5 cubic kilometers) of magma blasted through the floor of a broad glacial valley in what is now Katmai National Park and Preserve. Ash and pumice filled the upper Ukak River valley with multiple pulses of volcanic debris in places to a depth of more than 600 feet. Clouds of ash rose high into the atmosphere and drifted downwind, dropping more than a foot of ash on Kodiak, dusting Puget Sound, and eventually circling the globe. The far-traveled ash and gas cloud colored the sky over the Mediterranean and lowered global temperatures for a year or two. Later stages of the eruption produced a blocky lava dome, Novarupta, within the main vent depression. Novarupta ('new eruption') is 210 ft (65 m) tall by 1250 ft (380 m) diameter. Mount Katmai, an ice-clad stratovolcano 6 miles away, lost its summit in a dramatic collapse during the eruption to form a deep, steep-walled, steaming crater. Katmai initially stole the credit for this enormous eruption until the 1950s when geologist Garniss Curtis carefully mapped ash thicknesses that identified Novarupta as the source. Very little material actually erupted at Katmai: a small dacite dome formed on the floor of the crater sometime after its collapse. It is now underneath more than 800 feet of water. The great Novarupta-Katmai eruption was an event of planetary importance. Please join us as we trace the events of 1912 in June, July, and through the rest of the summer. Much of the material we will present is taken from the many detailed publications by geologists Wes Hildreth and Judy Fierstein of the U.S. Geological Survey. We refer interested followers to their publications for more detail and citations to original accounts. Hildreth and Fierstein, 2012
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