when is the last time mt hood erupted
Mount Hood The last three eruptions at Mount Hood occurred within the past 1,800 years from vents high on the southwest flank and produced deposits that were distributed primarily to the south and west along the Sandy and Zigzag rivers. The last eruptive period took place around 220 to 170 years ago, when dacitic lava domes, pyroclastic flows and mudflows were produced without major explosive eruptions. The prominent Crater Rock just below the summit is hypothesized to be the remains of one of these now-eroded domes. This period includes the last major eruption of 1781 to 1782 with a slightly more recent episode ending shortly before the arrival of the explorers Lewis and Clark in 1805. The latest minor eruptive event occurred in August 1907.[22][23]
Mount Rainier The most recent recorded volcanic eruption was between 1820 and 1854, but many eyewitnesses reported eruptive activity in 1858, 1870, 1879, 1882 and 1894 as well.[38]
Mount Rainier The most recent recorded volcanic eruption was between 1820 and 1854, but many eyewitnesses reported eruptive activity in 1858, 1870, 1879, 1882, and 1894 as well.[38]
Mount Mazama Mazama was last active about 4,800 years ago, when an eruption took place near Wizard Island's eastern base.[96] This eruption took place underwater,[93] and it produced viscous lava that created a rhyodacite lava dome, about 2,400 years after the first period of postcaldera activity.[97] Given that Mazama has had periods of sporadic eruptions for 420,000 years, the United States Geological Survey thinks that it is "virtually certain" that Mazama will erupt again in the future.[6][98] Mazama is considered dormant, but it remains monitored by the United States Geological Survey Cascades Volcano Observatory.[21] Future eruptions would likely take place near the western side of the complex and within the caldera rim; they could occur underwater. The ejection of lava rich in gas from shallow water could produce huge ash columns, but submarine eruptions at deeper depths may decrease the explosiveness of the event. Nonetheless, the rapid mixing of water and lava could produce dangerous pyroclastic surges, which are more gaseous and less solid than pyroclastic flows.[6] Such flows could pass over topographic barriers, move rock fragments at rapid speeds of 800 feet per second (240 m/s), and travel several miles from their vent.[99] Mazama is unlikely to produce mudflows far from the caldera, though a nearby vent outside the caldera could erupt and mix with snow. Eruptions are unlikely to produce waves that extend beyond Crater Lake, but powerful explosions could produce tall waves in the caldera.[100] An eruption as explosive as the one 7,700 years ago is unlikely given that it would require larger volumes of magma than are known to be available within the Mazama vicinity.[39] Moreover, landslides could flood adjacent shoreline regions, but they are not likely to induce failure of the caldera's walls, as they rise more than 500 feet (150 m) above the lake's surface.[39] Earthquakes from the nearby West Klamath Lake fault zone could reach magnitudes up to 7.0 on the Richter scale, but these only occur every 3,000 to 10,000 years; they could generate tall waves by creating landslides.[39] Though local earthquakes from volcanic activity would create motion in the lake, they would likely only reach maximum magnitudes of 5.0 on the Richter scale. However, Crater Lake is poorly monitored, and not highly active seismically among the Cascade volcanoes.[101] The largest earthquake threat originates from the Cascadia subduction zone, which could produce earthquakes with a magnitude of 8 or 9 that could lead to huge waves in Crater Lake.[32]