Sierra Nevada Earthquake Swarm

Release Date:

The USGS California Volcano Observatory (CalVO) is tracking an earthquake swarm in the Sierra Nevada range south of Long Valley Caldera, about 8 miles SW of Toms Place and 15 miles SE of the town of Mammoth Lakes.

Presently, the swarm, which started on Thursday October 9th, includes over fifty earthquakes of magnitude M1.0 and greater, including five between M3.0 - 3.6 that produced mild shaking in the vicinity of Mammoth Lakes and Bishop. The swarm appears to be the result of movement along a regional fault structure (so-called "tectonic" earthquakes). There are no observed changes in caldera seismicity or deformation. The swarm poses no immediate threat to people or property. CalVO will continue to closely track this activity and provide updates as appropriate.