Minor M 3.7 Earthquake Reported 25 km West of Petrolia, California
Areazine synthesizes this USGS earthquake report directly from USGS's official public data feed. See our methodology for full source attribution and refresh cadence.
A minor 3.7 magnitude earthquake occurred offshore near Petrolia, California, on March 20, 2026. The shallow quake resulted in no tsunami warnings.
What this USGS earthquake report tells you, and what most readers miss
This notice was issued by USGS on April 3, 2026 and geographically references Northern California. Its severity classification of "low" signals how the issuing agency weighs the risk of harm if no action is taken - "critical" and "high" tier alerts typically carry direct consumer actions, while "medium" and "low" tend toward informational guidance or monitoring advisories. The category it belongs to - Earthquakes - determines the monitoring protocol behind it, which shapes what follow-up action (checking for structural damage, watching for aftershocks, reviewing local building codes) is relevant and which agency holds authority over the assessment.
Most readers skim a notice like this, check whether they are personally affected, and move on. The more useful lens is to verify its scope, source, and timestamp, then compare related notices without assuming that one record proves a broader trend.
Areazine pairs this record with the original agency URL so you can check the primary source before acting. Its related labels are earthquake, seismic, usgs, Northern California.
What Happened
A minor earthquake with a magnitude of 3.7 mw was recorded on March 20, 2026, at 12:56 UTC (5:56 AM PDT). The event was centered approximately 25 km west of Petrolia, California, according to data from the U.S. Geological Survey (USGS).
Location Details
The earthquake occurred at a depth of 19.33 km, which is classified as a shallow event. Shallow earthquakes, occurring at depths of less than 20 km, are often more noticeable to those nearby than deeper seismic activity. The epicenter was located at coordinates 40.3065°N and 124.5845°W, positioned off the coast of Northern California.
Impact Assessment
There is no tsunami advisory, watch, or warning in effect for this event. The USGS reported a Modified Mercalli Intensity (MMI) of 2.583, suggesting weak shaking near the epicenter. No felt reports were logged at the time of the report, and no damage or injuries have been documented in connection with this routine seismic activity.
What You Should Know
Earthquakes with magnitudes between 2.5 and 3.9 are classified as minor. While they are frequently felt by residents, they rarely cause damage to buildings or infrastructure. Residents in the region should remain aware that aftershocks are a possibility following any seismic event, though they are typically smaller than the initial quake.
Source
Data provided by the USGS Earthquake Hazards Program.
Original source: USGS Official Notice ↗
Related Earthquakes
All Earthquakes →Frequently Asked Questions
Common questions about this USGS earthquake report.