December 20, 2022 Earthquake: Humboldt County, California, United States

Reference #13456:

Two people killed, 17 injured and 100 displaced; damage to a bridge and 150 homes damaged or destroyed; gas leaks and power outages occurred in Humboldt County. Rio Dell, CA, US - CDI: 8; Ferndale, CA, US - CDI: 7; Fortuna, CA, US - CDI: 7; Loleta, CA, US - CDI: 7; Scotia, CA, US - CDI: 7

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.

Two people killed, 17 injured and 100 displaced; damage to a bridge and 150 homes damaged or destroyed; gas leaks and power outages occurred in Humboldt County.

Reference #13400, #134001:

The earthquake, which began at 2:34 a.m. 7.5 miles from Ferndale, caused widespread damage to road [....] The deaths were caused by medical emergencies during or shortly after the earthquake [...] “We know that there is one structure fire and we also know that there were a couple of homes that may have been knocked off their foundation, or partially collapsed,” Mark Ghilarducci, director of the California Governor’s Office of Emergency Services, said at a news conference.

Rio Dell is without water, electricity, internet and gas.

In Eureka, where electricity is down, incoming-Mayor Kim Bergel said she saw several broken windows in storefronts around town, which were being boarded up with plywood.

Reference #1250:

2 deaths, 12 injured, 250 million USD total damages

Reference #13435:

Impacts to Humboldt County, CA: 2 deaths, 17+ injured, 90+ structures deemed unsafe, 170+ residents displaced, 31+ million USD in damages to public infrastructure. (Note: this includes impacts from the magnitude 5.4 aftershock on 01 January 2023)

Reference #13723, #13727:

$150 million in economic losses

Note: The two people who died, ages 72 and 83, suffered the medical emergencies, including a cardiac incident, during or just after the temblor. Emergency responders couldn’t get to them in time because the few ambulances located in the area were already dispatched elsewhere, said Humboldt County Sheriff William Honsal.