StEER has released an Event Briefing for the recent M6.2 earthquake in Northern California:
Mosalam, K. Gunay, S. Kijewski-Correa, T. Robertson, I. (2021) "Petrolia Earthquake Event Briefing", in StEER - 20 December 2021, Petrolia, Mw 6.2 Earthquake. DesignSafe-CI. https://doi.org/10.17603/ds2-4m8k-eh86.
There are a large number of ground motion recording stations in the vicinity of the epicenter of this earthquake including two instrumented bridges in the earthquake area, supporting ongoing study of this earthquake.
A ground motion recording station in Ferndale, CA recorded a peak ground acceleration (PGA) of 28.7% g, which led to minor nonstructural damage. If these preliminary values are accurate, the observation of no structural damage indicates good seismic performance of structures in this region.
California's Office of Emergency Services indicated that 2,500 people were notified about the earthquake in advance of strong shaking through the state's earthquake early warning system.
This earthquake is another reminder of the potential of major earthquakes along the Pacific coast; coupled with the earlier flurry of earthquakes off the Oregon coast, attention should be given to this series of strike-slip earthquakes along the flanks of the Juan de Fuca plate.
Based on these findings, StEER will maintain this response at a Level 1 culminating in this product and will not activate a VAST or FAST unless further damage reports surface.