USGS: 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 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.
Humboldt County Sheriff:
Just after 2:30 am, Tuesday, December 20, an M6.4 earthquake struck 14 miles from Fortuna, CA. NO TSUNAMI IS EXPECTED AT THIS TIME.
- Do not call 911 unless you are experiencing an immediate emergency.
- Record and photograph all damages to your home prior to clean up.
- Turn off gas lines and report gas leaks immediately to PG&E at: 1-800-743-5000
- Check water lines for damages. Contact your local water district for any water-related questions.
- Use caution traveling.
- Damage assessments are underway throughout Humboldt County.
- Over 70K customers are without power as of 5:45 a.m. Estimated restoration time is unavailable.
- Widespread damage has been reported to roads and homes, particularly in the Eel River Valley.
- Two injuries have been confirmed.