LASSEN VOLCANIC NATIONAL PARK (CBS SF) -- It quietly built up magma for 27,000 years before beginning a 7-year-long series of eruptions on May 30, 1914 and today geologists closely monitor Northern California's most active volcano for any signs that last century's eruptions could resume.
Lassen Peak, commonly called Mount Lassen, is surrounded by placid blue lakes, green meadows and sparse population which convey an air of tranquility. It's so literally radio silent that the SETI Institute's Allen Telescope Array is based here, far removed from the electronic pollution of cellphones and broadcasters in the cities to the south. All this beneath the shadow of a towering mountain, one that awoke 100 years ago this Friday from a 27,000 year sleep.
Lassen Peak was the only volcano to erupt inside the borders of the United States until 1959, when Hawaii and Alaska were added to the union.
That first, small eruption of May 30, 1914 was followed by more than 180 outbursts the following year, climaxing, in May 1915, with two big blasts that melted the summit snow pack and sent mudflows roaring down Lassen's northeast flank, damaging cabins and ranches in their path and knocking down trees along a wide swath now called the Devastated Area.
Lassen Peak continued to pop off sporadically for several more years. When the activity was finished in the early 1920s, the death toll stood at a perfect zero, despite a few close calls when sightseers, scientists and photographers got caught on its slopes during eruptions.
Lassen Peak is at the southern end of the Cascade Range which includes nearby Mount Shasta and the still-active Mount St. Helens. Scientists believe all those volcanoes could erupt again explosively at any time.
The U.S. Geological Survey takes measurements of volcanic gas and constantly monitors ground movements around the mountain, transmitting the data to Menlo Park for real-time analysis. If anything changes, scientists can race to the region to take the volcano's vital signs. So far, it remains quiet.
One of the old eruptions is thought to have been captured on motion picture film by Justin Hammer, who lived on Catfish Lake near Lassen Peak. This film is believed to have been shot in 1917. It is a silent film, but sound effects were later added by Hammer's grandson, Craig Martin.
MORE DETAIL ON THE FILM: http://www.networkedblogs.com/Dp6i0
NATIONAL PARK SERVICE: Lassen Peak History & Eruption Danger
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