M 3.3 - 18 km WSW of Johannesburg, CA
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 magnitude 3.3 earthquake occurred 18 km west-southwest of Johannesburg, California on April 28, 2026.
What this USGS earthquake report tells you, and what most readers miss
This notice was issued by USGS on June 7, 2026 and geographically references Southern 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, California.
What Happened
A M 3.3 ml earthquake struck at 12:00:57 UTC on April 28, 2026 (Unix time 1780020057490). The event was located 18 km WSW of Johannesburg, CA, at a depth of 6.88 km.
Location Details
The epicenter was at coordinates 35.2997°N, 117.8120°W. The shallow depth of 6.88 km classifies this as a shallow earthquake (less than 20 km).
Impact Assessment
No felt reports were recorded. There was no tsunami advisory (tsunami field = 0) and no alert level issued.
What You Should Know
Earthquakes of this magnitude (M 2.5-3.9) are often felt but rarely cause damage. Minor aftershocks remain possible.
Source
Original source: USGS Official Notice ↗
Related Earthquakes
All Earthquakes →Nationwide notices with similar length or severity timing 8
Two Areazine-derived peer sets for this USGS earthquake report: nearest notices by body length and by same severity near the same agency date. Peers come from other categories so they are not the same-feed Related list above.
Similar body length
Nearest notices by article body length (710 characters here).
Similar severity timing
Same severity (low) notices issued closest in time to June 7, 2026.
Frequently Asked Questions
Common questions about this USGS earthquake report.