USGS logo

 Three moderate earthquakes south of the caldera and one beneath the caldera on May 25-26, 1980, marked the beginning of unrest that continues into the 1990's. Swarms of earthquakes beneath the caldera, changes in several hot springs, and the formation of new springs have occurred since 1980. Precise surveys have also shown that the central part of the caldera has risen by more than 50 centimeters since 1975. This unrest is probably related to the stretching (east-west extension) of the Earth's crust that is known to be occurring in the region around the caldera, and it probably also involves the rise of magma beneath the caldera. Scientists do not know if this unrest will lead to volcanic activity, but the geologically recent eruptions along the Mono-Inyo Craters Volcanic Chain suggest that future eruptions are possible.


South Inyo Crater, Long Valley Caldera, California. Explosive eruptions formed the crater about 500 years ago. (Photograph by Steven R. Brantley.)

 South Inyo Crater, Long Valley Caldera

Maintained by John Watson
Updated 06.24.97

back start of book next page