Figure 8. Seismicity before and after the 2021 magnitude 6.2 Petrolia earthquake and 2022 magnitude 6.4 Ferndale earthquake in Northern California. Earthquakes of all magnitudes and depths were taken from the USGS catalog. (a) Seismicity in the 7 days preceding the December 20, 2021 magnitude 6.2 event. (b) Aftershocks during the 7 days following the 2021 mainshock. (c) Seismicity in the 7 days preceding the December 20, 2022, magnitude 6.4 Ferndale earthquake. (d) Aftershocks during the 7 days following the 2022 mainshock. Credit: Temblor, CC BY-NC-ND 4.0