M2.5 earthquake 17km WSW of Petrolia, CA

A magnitude 2.5 earthquake struck 17km WSW of Petrolia, CA on Thu, Sep 23, 2021, 12:46 AM PDT (07:46 UTC), 21 km (13 mi) below the surface.

A larger quake followed: M4.4 5km NNE of Petrolia, CA. This one was a foreshock.

Map

Where this earthquake was located, with the others nearby. Select one for its page.

Different scales measure different things and differ by a few tenths. The USGS marks one as preferred, and it is the one this page uses.

Mag.	Scale	Computed by	Notes
2.5	Md, duration	Northern California Seismic System	Preferred · Final · ±0.063 · 17 stations
2.2	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed · ±0.06 · 36 stations

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

Distance and direction from each place to the epicenter, with its forecast.

Within 100 km, magnitude 1.5 and up: 53 in the 60 days after this one and 32 in the 30 days before it.

From the USGS Earthquake Hazards Program and its partner networks, event nc73628341 (also filed as us7000fdqv). Read Sun, Oct 4, 2026, 3:26 PM UTC.