M1.2 quarry blast 5 km NNW of Azusa, California, United States
A magnitude 1.2 quarry blast struck 5 km NNW of Azusa, California, United States at 12:37 local time (19:37 UTC) on 23 Sept 2026, at a depth of -1 km, according to USGS.
Data: USGS · updated 2026-09-23 20:13 UTC · reviewed
- Magnitude
- 1.2micro
local magnitude (Richter) (ml) - Depth
- -0.9 km
- Status
- Reviewed
- Origin time
- 2026-09-23 19:37:42 UTC
- Local: 23 Sept 2026, 12:37:42 (America/Los Angeles)
- Epicentre
- 34.173° N, 117.931° W
Circles show this event and others within 30 km from 7 days before to 30 days after. Lines: plate boundaries and GEM active faults. Open on the live map
Nearby places
| Place | Distance | Est. shaking |
|---|---|---|
| AzusaCalifornia, United States · pop. 49,690 | 5 km | INot felt |
| DuarteCalifornia, United States · pop. 21,990 | 6 km | INot felt |
| GlendoraCalifornia, United States · pop. 52,009 | 7 km | INot felt |
| MonroviaCalifornia, United States · pop. 37,463 | 7 km | INot felt |
| Los AngelesCalifornia, United States · pop. 3,820,914 | 32 km | INot felt |
| AnaheimCalifornia, United States · pop. 350,742 | 37 km | INot felt |
| Santa AnaCalifornia, United States · pop. 310,227 | 47 km | INot felt |
| Long BeachCalifornia, United States · pop. 474,140 | 51 km | INot felt |
Shaking is an estimate from the intensity prediction equation of Allen, Wald & Worden (2012), not an observation. Local ground and buildings can change it by a level or more. Likely felt out to about 2 km.
Every agency's solution
Agencies locate earthquakes with their own stations and methods, so their numbers differ. We match reports of the same event by time, distance and magnitude and show them side by side. The headline uses USGS · CI, which has been reviewed by an analyst.
| Agency | Magnitude | Depth | Epicentre | Time offset | Status |
|---|---|---|---|---|---|
| USGS · CIheadlineSouthern California Seismic Network via U.S. Geological Survey | 1.2 ml | -0.9 km | 34.17° N, 117.93° W | – | Reviewed |
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How big was it?
Usually not felt. Recorded by nearby seismometers; thousands occur worldwide every day.
It released roughly the energy of 888 g of TNT. Magnitude is logarithmic: each whole step means about 32 times more energy and 10 times larger waves on a seismogram. Depth matters too: at -1 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.
M1.2 releases about 1.9× the energy of M1.0, and its waves are about 1.5× taller on a seismogram. Energy: 888 g of TNT vs 477 g of TNT.
Each square is the energy of one M1.0. Energy from log₁₀E = 1.5M + 4.8.
Aftershocks and nearby activity
No later earthquakes have been recorded within 30 km so far. 1 in the 7 days before. Aftershock rates usually fall off roughly in proportion to 1/time.
Did you feel it?
Reports from people help show where shaking was strong. They are anonymous and shown here in aggregate.
Reports on SeismoAtlas
No reports yet.
Event id ci41337911. First recorded here 28 Sept 2026, 17:32:11 UTC. Solutions: USGS · CI (usgs:ci41337911). Cite as: SeismoAtlas, “M1.2 quarry blast 5 km NNW of Azusa, California, United States”, https://seismoatlas.com/earthquake/ci41337911-m1-2-quarry-blast-5-km-nnw-of-azusa-california-united-states, data from USGS.
JSON: /api/v1/events/ci41337911. SeismoAtlas is not an official warning service.