Recent Earthquakes in California and Nevada
== PRELIMINARY EVENT REPORT ==
U.S. Geological Survey, Menlo Park, California
U.C. Berkeley Seismological Laboratory, Berkeley, California
Version #3: This report supersedes any earlier reports of this event. This event has been reviewed by a seismologist.
A micro quarry occurred at 11:55:49 AM (PDT) on Wednesday, August 27, 2025.
The magnitude 1.6 event (a probable quarry explosion) occurred 3 km (2 miles) SW of Clayton, CA.
The hypocentral depth is -0.26 km (-0.20 miles).
| Magnitude | 1.6 - duration magnitude (Md) |
| Time | Wednesday, August 27, 2025 at 11:55:49 AM (PDT) Wednesday, August 27, 2025 at 18:55:49 (UTC) |
| Distance from |
Clayton, CA - 3 km (2 miles) SW (223 degrees) Concord, CA - 7 km (4 miles) SE (139 degrees) Waldon, CA - 8 km (5 miles) E (95 degrees) Walnut Creek, CA - 9 km (6 miles) E (81 degrees) Pleasant Hill, CA - 9 km (6 miles) ESE (110 degrees) |
| Coordinates | 37 deg. 55.2 min. N (37.919N), 121 deg. 57.7 min. W (121.962W) |
| Depth | -0.26 km (-0.20 miles) |
| Quality | Good |
| Location Quality Parameters | Nst=15, Nph=15, Dmin=3.7 km, Rmss=0.06 sec, Erho=0.22 km, Erzz=31.61 km, Gp=68 degrees |
| Event ID# | nc75229467 |
| Additional Information | Map |
For more information, see https://earthquake.usgs.gov
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