Sunday, August 01, 2010
"Volcanoes" episode of "This Angry Earth" on Weather Channel covers Mt. St. Helens, and Mammoth Lakes risk
Most of the episode focused on the May 1980 eruption of Mount St. Helens in Washington State. The May 18 eruption occurred after a series earthquake caused a landslide and unplugged a volcanic cap, which exploded the way a pop bottle fizzles.
The show focused on local hermit Harry Truman, as well as a young geologist, and others who lost their lives when they were obliterated. Various sites around the mountain were covered with 300 feet of ash, and the mountain lost over 1300 feet of elevation, a kind of natural “mountaintop removal”.
The show went on to cover the apocalyptic hazard posed by other Cascade Range volcanoes, especially Mt. Rainier itself, which could become vulnerable to an explosive eruption after a landslide.
The show then covered the hazard of the Mammoth Lakes area (also Mono Lake) of the Sierras in California, along US 395, somewhat north of Bishop. An explosive eruption could obliterate everything for 75 miles, and cover the entire country with an ash cloud. I've been in the area several times.The supervolcano caldera around Yellowstone has erupted once every 600000 years (moving East with each eruption) but that hazard was not discussed.
Mount Pinatubo in the Philippines erupted explosively in 1991 and was discussed, as were other eruptions in the West Indies and Colombia.
YouTube video of eruption by Spikedeadman:
Wikipedia attribution link for NASA view of St. Helens. I flew over it in a commercial flight from Seattle in August, 1980.