A hundred years ago today, June 6, the largest volcanic eruption of the 20th century shook Alaska. Ned Rozell of the Alaska Science Forum reports that the Novarupta-Katmai volcanic eruption of 1912 spewed 100 times as much material as Mount St. Helens, and ash reached as far as the Mediterranean Sea. If the ash were deposited on top of Anchorage, the city would be buried 3 miles deep.

The eruption occurred on the Alaska Peninsula, in what is now the Katmai National Park. Sometime during the next three days, Mount Katmai, located six miles away, caved in on itself. Today, the former mountain is a crater lake surrounded by 300-foot walls, into which glaciers calve.

Four years after the eruption, in 1916, the botanist Robert Griggs visited the valley, and later wrote that he and others were "overawed" by what they saw. Steam flowed from vents across the barren, ash-covered valley; Griggs named it The Valley of Ten Thousand Smokes.

Despite the magnitude of the explosion, only one person died, a woman already afflicted with tuberculosis, on a boat in Kodiak.

Read much more about this magnificent event, here.