M 6.4 - 15km WSW of Ferndale, CA
- 2022-12-20 10:34:24 (UTC)
- 40.525°N 124.423°W
- 17.9 km depth
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VIIImmi 
Estimated Intensity Map - PAGER
ORANGE 
Estimated Economic Losses 
Estimated Fatalities Ground Failure - Landslide Estimate
Limited area affected
Limited population exposed
- Liquefaction Estimate
Limited area affected
Limited population exposed
Origin - Review Status
- REVIEWED
- Magnitude
- 6.4 mw
- Depth
- 17.9 km
- Time
- 2022-12-20 10:34:24 UTC
Moment Tensor Fault Plane Solution Finite Fault 
Cross-section of slip distribution. Tsunami 
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View Nearby Seismicity - Time Range
± Three Weeks - Search Radius
250.0 km - Magnitude Range
≥ 3.0
ShakeAlert ® 
Contributors NC
California Integrated Seismic Network: Northern California Seismic System (UC Berkeley, USGS Menlo Park, and Partners)
Tectonic Summary
The December 20, 2022, M 6.4 earthquake occurred approximately 15 km southwest of Ferndale, California near the coast of northern California in the vicinity of the Mendocino triple junction – the region where the Pacific, North America, and Juan de Fuca/Gorda plates meet. Focal mechanism solutions indicate that rupture occurred as a result of strike-slip faulting on a steeply dipping fault striking either southeast or southwest. The location, depth and faulting mechanism indicate that this event likely occurred within the subducting Gorda Plate.
Earthquakes are common in the region around the Mendocino triple junction. Oblique motion between the southern Juan de Fuca/Gorda plate and Pacific plate causes north-south compression within the Gorda plate and right-lateral translation along the boundary between the plates. A M 6.2 event occurred approximately 20 km to the southwest of the 2022 M 6.4 earthquake one year prior, on December 20, 2021. In the past century, there have been at least 40 other earthquakes of M6 or larger, including six earthquakes M7 or larger, within 250 km of the December 20, 2022 earthquake. These prior earthquakes primarily occurred along the Mendocino transform fault, in the Cascadia subduction zone, or within the Juan de Fuca/Gorda plate.