As far as I can tell, last night’s M4.3 #earthquake near Joesph, #Oregon was the largest earthquake ever recorded in Wallowa County!
I searched through the USGS catalog and through historical newspapers and couldn’t find anything bigger since at least the late-1800s. That isn’t to say that earthquakes of this size are unexpected in Wallowa County, just that they’re quite rare.
This earthquake was near the Wallowa Fault. The Wallowa Mountains continue to rise thanks to uplift south of this line plus the valley dropping to the north. Seismologists will explore the role this fault did or didn’t play as they investigate this event.
Small aftershocks are possible over the next couple weeks. There is a non-zero (but quite low) chance that this is a foreshock of a larger event. In either case, if you feel an earthquake remember to drop, cover, and hold on.
The largest historic earthquake in the area was the M5.8 State Line earthquake which struck near Walla Walla in 1936.
@ingalls Hmm, is that a volcano?