Mount Shasta
Image by U.S. Geological Survey
Mount Shasta — Mount Shasta is located in the Cascade Range in northern California about 65 km (40 mi) south of the Oregon-California border. One of the largest and highest (14,162 ft) of the Cascade volcanoes, the compound stratovolcano is located near the southern end of the range that terminates near Lassen Peak. The last known eruption occurred about 200 radiocarbon years ago, and may have occurred in 1786.
The next eruption at Mount Shasta would likely involve weeks to months of precursory earthquakes and ground deformation followed by a series of steam explosions blasting a deep crater at the summit of the volcano. Steam explosions would be followed by slow extrusion and accumulation of partially molten rock in the crater, leading to the formation of a steep-sided lava dome. Periodic collapse of the growing dome would generate explosions with vertical ash columns up to 8 km (5 mi) high. Fast moving avalanches (pyroclastic flows) of hot dome rock racing down the flanks of the volcano would melt ice and snow creating mudflows (lahars) capable of flooding drainages many kilometers away.
Learn more about Mount Shasta: on.doi.gov/MountShasta
In this photo: Mount Shasta and Shastina (background) with Sheep Rock (foreground). Debris avalanche hummocks can be seen to the right. Credit: Mark Stensaas
