QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

Earthquake near South El Monte, CA

No earthquake was likely felt in South El Monte in the 24 hours to 5:46 am PST (13:46 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 1.8 earthquake was recorded 3 km (2 mi) west of South El Monte, CA, at 1:48 pm PDT on 19 September 2020 (20:48 UTC), 18 km deep. 4 people have reported feeling it to USGS.

USGS: 3km W of South El Monte, CA

in Montebello, CA · 30 km (19 mi) E of Los Angeles, CA

1:48 pm PDT, Sep 19, 2020 · · 18 km deep · released about 13 lb of TNT

Every earthquake near South El Monte Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Los Angeles County 23 kmOrange County 50 kmVentura County 103 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
1:48 pm PDT on 19 September 2020 ()
Where
3 km (2 mi) west of South El Monte, CA · earthquakes near South El Monte
Magnitude
M 1.8 (ml)
Depth
18 km below the surface
Felt
4 reports · strongest reported intensity III
Nearest
Los Angeles County, 23 km NW
Nearest mapped fault
Raymond fault, 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 2243 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. 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.

Earthquakes near other towns within 30 km: South San Gabriel, Rosemead, Monterey Park, Montebello, El Monte, San Gabriel.

How big was it?

This earthquake released about 13 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 810,000× the energy of this one
  3. Around the size people start to feel M 3.0 72× the energy of this one
  4. This earthquake M 1.8 about 13 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 15,000 times the energy of this one.

Before 2016, the USGS record lists 20 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.7 Northridge, California, earthquake · 46 km WNW of this epicentre
  2. 6.6 1971 San Fernando Earthquake, California · 49 km NNW of this epicentre
  3. 6.4 The 1933 Long Beach, California Earthquake · 47 km S of this epicentre
  4. 5.9 The 1987 Whittier Narrows, California Earthquake · 1 km NNE of this epicentre
  5. 5.9 1km ENE of Granada Hills, California · 45 km WNW 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 34.0497, -118.0830. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Los Angeles County, CA 23 km (14 mi) NW earthquakes near Los Angeles County
Orange County, CA 50 km (31 mi) SE earthquakes near Orange County
Ventura County, CA 103 km (64 mi) WNW earthquakes near Ventura 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.

  1. 2.2 4km ESE of Altadena, CA
  2. 1.8 1km ENE of Baldwin Hills, CA
  3. 1.9 4km NNW of Orange, CA
  4. 1.5 2km SW of La Habra, CA
  5. 1.6 2km SW of La Habra, CA
  6. 1.7 2km SE of Placentia, CA
  7. 2.7 2km SSE of Placentia, CA
  8. 1.6 3km W of South El Monte, CA
  9. 1.8 2km NNE of Villa Park, CA
  10. 2.8 6km SSW of Pearblossom, CA
  11. 1.6 6km SSW of Pearblossom, CA
  12. 1.7 3km W of Sylmar, CA
  13. 1.7 1km W of Brea, CA
  14. 1.8 1km SE of San Fernando, CA
  15. 1.9 6km ENE of Villa Park, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.