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USGS Mount Hood South: Geology; Rock age: More than 500,000 years [3] Mountain type: Stratovolcano: Volcanic arc: Cascade Volcanic Arc: Last eruption: 21 September 1865 to January 1866 [4] Climbing; First ascent: July 11, 1857, by Henry Pittock, W. Lymen Chittenden, Wilbur Cornell, and the Rev. T. A. Wood [5] Easiest route: Rock and glacier climb
The volcanoes with historical eruptions include: Mount Rainier, Glacier Peak, Mount Baker, Mount Hood, Lassen Peak, and Mount Shasta. Renewed volcanic activity in the Cascade Arc, such as the 1980 eruption of Mount St. Helens , has offered a great deal of evidence about the structure of the Cascade Arc.
This is a list of Cascade volcanoes, ... Last eruption date Last eruption VEI ... Mount Hood: Stratovolcano: 3,426: 11,240:
Mount Hood, the nearest major volcanic peak in Oregon, is 60 miles (100 km) southeast of Mount St. Helens. Mount St. Helens is geologically young compared with the other major Cascade volcanoes. It formed only within the past 40,000 years, and the summit cone present before its 1980 eruption began rising about 2,200 years ago. [ 11 ]
To compare, Mt. St. Helens' eruption in 1980 was a level 4. Known as a super eruption for its magnitude, the event emptied out enough volcanic material to produce the 30-by-40-mile-wide caldera.
Seismologists hadn't monitored earthquake activity in the Mount St. Helens area until seismometers were installed near the volcano in 1972, and from January 1975 through early 1980, only 44 ...
Two of the four eruptions were previously identified: Mount Tambora in Indonesia exploded in 1815, and Cosegüina erupted in Nicaragua in 1835. The volcano that produced the 1808/1809 eruption ...
Estimates place the volcano's last eruption at 46,000 years ago, in the Late Pleistocene. [45] [46] North Sister possesses more dikes than any similar Cascade peak, caused by lava intruding into pre-existing rocks. Many of these dikes were pushed aside by the intrusion of a 980 ft (300 m)-wide volcanic plug.