Hazards

Future eruptions like those of the last 10,000 years will probably produce deposits of ash, lava flows, domes, and pyroclastic flows, and could endanger infrastructure that lie within several tens of kilometers of the volcano.

Many lava flows and one cinder cone erupted at several vents between 10,000 and about 2,000 years ago.

Based on this recent behavior, it is not likely that Mount Shasta will erupt very catastrophic volumes of tephra and ash in the near future.

The deposits of an exceptionally large debris avalanche extend from the base of Mount Shasta volcano northward across the floor of Shasta Valley in northern California.

If pyroclastic flows occur in the future, they may affect low- and flat-lying areas almost anywhere within about 20 km (12.4 mi) of the source vent for the eruption.

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.

If they occur in the future, lahars may cover valley floors and other low areas as much as several tens of kilometers (10 km = 6.2 mi) from the volcano.