Hearts of Volcanoes Beat Beneath Peaceful Facades

Hearts of Volcanoes Beat Beneath Peaceful Facades. . Mount Adams. Mount Hood. Mount St. Helens. These serene, snow-covered mountains beckon one to come closer. But beware. These mountains were born by repeated, often violent eruptions of ash, lava, and pumice., Their eruptions and landslides created mudflows that wiped out entire valleys. They will come to life again. It could be thousands of years from now. Or tomorrow., Mount Adams , 12,276 feet (3,742 meters) , About 460,000 years old , Most of visible cone is less than 40,000 years old , Located 34 miles east of Mount St. Helens, Recent Activity: , . 1,000-2,000 years ago: Last eruption , . 200 years ago: A mudflow almost 200 feet deep courses through a valley on the lower flank of the volcano. , . 1921: A landslide of rock and ice crashes down, burying 1.5 square miles of the west slope. Event possibly caused by a steam explosion. , . Today: Vents on the summit emit steam, and gas that weakens volcanic rock., The Future: , . Weak, upper core may collapse, producing avalanches and mudflows. , . Eruptions of thick lava from vents on summit and upper flanks. , . Large landslides and mudflows, with or without eruptions, pose the most destructive and far-reaching hazard., Mount Hood , 11,239 feet (3,426 meters) , About 500,000 years old , Most of visible cone is less than 200,000 years old , Located 62 miles southeast of Mount St. Helens, Recent Activity: , . 1780-1800: Crater Rock, the newest lava dome, is erupted. Flows of hot rock, ash and gas flow down the south flank, producing the smooth slope at today's Timberline Lodge and ski area. An eruption sends mudflows and debris into the Sandy and White Rivers, and then into the Columbia River, more than 35 miles away. , . 1859, 1865, 1903: Reports of eruptions accompanied by red glows or "flames." All eruptions small. , . Today: Several fumaroles (vents) emit steam and volcanic gases. Areas of warm ground on the upper southwest side., The Future: , . Small explosive eruptions with falling ash. , . Thick lava may ooze from vents near Crater Rock, building a new lava dome. , . Flows of hot ash and pumice. , . During eruptions or landslides, mudflows form from snow and ice melt. They may flow miles, perhaps reaching the Columbia River., Mount St. Helens , 8,328 feet (2,538 meters) in 2009 , About 300,000 years old , Most of visible cone is less than 2,800 years old, Recent Activity: , . 1800: Explosive eruption ejects 1/3 the volume of ash and pumice of the 1980 eruption. , . 1801: St. Helens erupts andesite lava, forming the 3-mile-long Floating Island lava flow. , . 1857: Last eruption before 1980. Goat Rocks lava dome extruded between 1842 and 1857. , . 1980: Landslide, cataclysmic lateral blast, and a nine-hour eruption. Blast destroys 230 square miles of forest. , . 1980 to 1986 and 2004 to 2008: St. Helens periodically erupts and extrudes lava domes inside the crater., The Future: , . Renewed dome growth and small to moderate explosive events, possibly occurring for decades to come. , . Mudflows generated by snowmelt from eruptive activity, landslides or intense storm runoff.