Earthquake Near Sonoma-Lake County Line Revised to Magnitude 4.3

Another aftershock hits the region as seismologists update initial readings.

Published on Feb. 22, 2026

Got story updates? Submit your updates here. ›

An earthquake with a revised magnitude of 4.3 struck northern Sonoma County on Saturday morning, followed by two smaller aftershocks. The initial quake was recorded at 9:22 a.m. about 15 miles north/northeast of Healdsburg and 3 miles southeast of the unincorporated Lake County area of Cobb. The USGS later revised the magnitude upward from the initial 4.1 reading. Two aftershocks, measuring 2.9 and 2.6 respectively, hit the same area in the following hours.

Why it matters

While no damage was reported from the largest quake, the seismic activity in this region is a reminder of the ongoing geological forces at play and the need for preparedness in earthquake-prone areas of Northern California.

The details

The 4.3 magnitude quake was recorded by the U.S. Geological Survey, with the initial 4.1 reading later revised upward by a USGS seismologist. The two aftershocks, measuring 2.9 and 2.6, hit the same general area in the hours following the main quake. Firefighters at the nearest Northern Sonoma County Fire Protection District station in Geyserville reported no impacts from the largest temblor.

  • The initial 4.3 magnitude quake struck at 9:22 a.m. on February 21, 2026.
  • A 2.9 magnitude aftershock hit about a mile south of the initial quake at 9:23 a.m.
  • A 2.6 magnitude aftershock was recorded at 12:17 p.m. the same day.

The players

U.S. Geological Survey

The federal agency responsible for monitoring and reporting on seismic activity in the United States.

Northern Sonoma County Fire Protection District

The local fire department serving the Geyserville area, which reported no impacts from the largest quake.

Got photos? Submit your photos here. ›

The takeaway

This seismic activity serves as a reminder for residents in earthquake-prone regions of Northern California to remain vigilant and prepared for potential future quakes, even if no immediate damage is reported.