Earthquake Swarm near Lassen Volcanic Center

The swarm is about 24 km WNW of the town of Chester and about 1 mile south of the Lassen Volcanic National Park boundary near the Twin Meadows Trail at Patricia Lake.

Since the start of the swarm about 80 earthquakes at or above magnitude M1.0 have been detected. A magnitude M3.86 earthquake at about 12:30 AM Nov 11 was the largest event to date. Preliminary analysis suggests that the earthquakes are related to regional fault motions along the northwest margin of the Walker Lane fault system. Ground deformation indicative of volcanic unrest has not been detected by nearby GPS receivers. Although the swarm poses no immediate threat, the CalVO will continue monitoring earthquake activity and keep in close communication with Lassen Volcanic National Park to learn of any changes in the Park's hydrothermal features.