Mount St. Helens' happened 550 years ago at the Inyo craters, which span Long Valley's north rim, and 650 years ago at the Mono craters, several miles north of the caldera. California's Long Valley is a 19-mile caldera created 730,000 years ago by an eruption 600 times larger than Mount St. Helens. The crater has been filled with lava for the last two million years, and it contains some of Earth's oldest rock formations. Residents refuse to heed warnings, remembering a 1982 false alarm that damaged tourism and aggravated a recession. Afterward, journalists were accused of sensationalism and scientists of scaring people to get more funding. Currently, 5-10 small quakes happen daily as the Earth's crust is stretched apart and magma fills half-mile-wide chambers four miles under the caldera, but the probability of eruption is less than one percent.
California's Long Valley is a 19-mile caldera created 730,000 years ago by an eruption 600 times larger than Mount St. Helens. The crater has been filled with lava for the last two million years, and it contains some of Earth's oldest rock formations. Residents refuse to heed warnings, remembering a 1982 false alarm that damaged tourism and aggravated a recession. Afterward, journalists were accused of sensationalism and scientists of scaring people to get more funding. Currently, 5-10 small quakes happen daily as the Earth's crust is stretched apart and magma fills half-mile-wide chambers four miles under the caldera, but the probability of eruption is less than one percent.