Earthquake Swarm Update: USGS Downgrades Susanville Quake to 4.9 Magnitude
SUSANVILLE, Calif. — The U.S. Geological Survey (USGS) has revised the magnitude of the significant earthquake that struck near Susanville, California, on December 30, 2025, downgrading it from initial reports of 5.3 to 4.9. The event occurred at approximately 9:49 p.m. PST, with the epicenter 14 km NNW of Susanville at a depth of 5.3 km, contributing to ongoing shaking in Lassen County.
A persistent swarm of earthquakes has shaken the remote Northern California town of Susanville and surrounding Lassen County since late December, with the latest significant jolt registering a magnitude 4.9 on December 30, 2025, at approximately 9:49 p.m. PST. The U.S. Geological Survey (USGS) reported the epicenter about 8 miles north-northwest of Susanville at a shallow depth of 5.6 miles, amplifying the felt intensity and prompting reports of strong shaking from local residents.
This event follows a magnitude 4.7 quake earlier that day, centered between Magalia and Reno, which was also widely felt but caused no reported damage or injuries. The swarm, which began intensifying around December 28 with a magnitude 5.0—described as the largest in the area in 136 years—has produced dozens of smaller tremors ranging from 2.1 to 2.8 on December 30. Seismologists attribute the activity to the tectonically active Walker Lane shear zone, separate from other recent California swarms like those near San Ramon.
Locals have described the quakes as unsettling, with items shifting and buildings rattling, but emergency officials confirm no major impacts so far. As of December 31, the USGS advises residents to stay prepared for potential aftershocks, emphasizing “drop, cover, and hold on” protocols. Monitoring continues, with real-time updates available on the USGS website.
