Earthquake · reviewed by a seismologist
M 2.3ml
Earthquake near South El Monte, CA
No earthquake was likely felt in South El Monte in the 24 hours to 1:55 pm PST (21:55 UTC). The last one was M 3.2, 32 km (20 mi) SSW, at 12:44 am PDT on 9 October 2026, estimated intensity II (weak) in town; 1,090 felt reports to USGS. Every earthquake near South El Monte
This page: a magnitude 2.3 earthquake was recorded 3 km (2 mi) west-southwest of South El Monte, CA, at 11:58 pm PDT on 23 September 2020 (06:58 UTC), 17 km deep. 45 people have reported feeling it to USGS.
USGS: 3km WSW of South El Monte, CA
in Montebello, CA · 31 km (19 mi) E of Los Angeles, CA
- When
- 11:58 pm PDT on 23 September 2020 ()
- Where
- 3 km (2 mi) west-southwest of South El Monte, CA · earthquakes near South El Monte
- Magnitude
- M 2.3 (ml)
- Depth
- 17 km below the surface
- Felt
- 45 reports · strongest reported intensity III
- Nearest
- Los Angeles County, 24 km NW
- Nearest mapped fault
- Puente Hills blind thrust system, 9 km from its surface trace — near is not the same as on
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 2234 days ago
Earthquake alerts for South El Monte, CA
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Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.
At this magnitude and depth, people at rest would likely notice it out to about 10 km (6 mi) from the epicentre. In South El Monte, 3 km away, the estimate is intensity II (weak). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.
Likely felt in: South El Monte 3 km, intensity II · Rosemead 4 km, intensity II · Montebello 4 km, intensity II · Monterey Park 5 km, intensity II · El Monte 5 km, intensity II · San Gabriel 7 km, intensity II · Pico Rivera 7 km, intensity II · West Whittier-Los Nietos 7 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 85 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
- Magna, Utah 2020 M 5.7 130,000× the energy of this one
- Around the size people start to feel M 3.0 11× the energy of this one
- This earthquake M 2.3 about 85 lb of TNT
Energy from the Gutenberg–Richter relation (log10E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.
For this area
The largest earthquake within 50 km since 2016 was M 4.5 on 2020-09-19 — about 2,300 times the energy of this one.
Before 2016, the USGS record lists 20 earthquakes of M5 or more within 50 km; the five largest:
- 6.7 Northridge, California, earthquake · 46 km WNW of this epicentre
- 6.6 1971 San Fernando Earthquake, California · 50 km NNW of this epicentre
- 6.4 The 1933 Long Beach, California Earthquake · 46 km S of this epicentre
- 5.9 The 1987 Whittier Narrows, California Earthquake · 2 km N of this epicentre
- 5.9 1km ENE of Granada Hills, California · 46 km NW of this epicentre
Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.
Where
Epicentre 34.0422, -118.0767. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Los Angeles County, CA | 24 km (15 mi) | NW | earthquakes near Los Angeles County |
| Orange County, CA | 49 km (31 mi) | SE | earthquakes near Orange County |
| Ventura County, CA | 103 km (64 mi) | WNW | earthquakes near Ventura County |
| San Diego County, CA | 165 km (103 mi) | SE | earthquakes near San Diego County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
52 earthquakes have been recorded within 50 km since this one.
- 3.5 2km W of Willowbrook, CA
- 1.5 10km SW of Corona, CA
- 2.0 8km E of Yorba Linda, CA
- 2.2 4km ESE of Altadena, CA
- 1.8 1km ENE of Baldwin Hills, CA
- 1.9 4km NNW of Orange, CA
- 1.5 2km SW of La Habra, CA
- 1.6 2km SW of La Habra, CA
- 1.7 2km SE of Placentia, CA
- 2.7 2km SSE of Placentia, CA
- 1.6 3km W of South El Monte, CA
- 1.8 2km NNE of Villa Park, CA
- 2.8 6km SSW of Pearblossom, CA
- 1.6 6km SSW of Pearblossom, CA
- 1.7 3km W of Sylmar, CA
Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.
On USGS
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.