Earthquake · reviewed by a seismologist
M 4.9mw
Earthquake near Westmorland, CA
No earthquake was likely felt in Westmorland in the 24 hours to 2:50 pm PST (22:50 UTC). The last one was M 4.9, 79 km (49 mi) SSE, at 10:27 am PST on 3 November 2026, estimated intensity III (weak) in town; 321 felt reports to USGS. Every earthquake near Westmorland
This page: a magnitude 4.9 earthquake was recorded 3 km (2 mi) northeast of Westmorland, CA, at 5:31 pm PDT on 30 September 2020 (00:31 UTC), 14 km deep. 368 people have reported feeling it to USGS.
USGS: 4km NE of Westmorland, CA
- When
- 5:31 pm PDT on 30 September 2020 ()
- Where
- 3 km (2 mi) northeast of Westmorland, CA · earthquakes near Westmorland
- Magnitude
- M 4.9 (mw)
- Depth
- 14 km below the surface
- Felt
- 368 reports · strongest reported intensity VI
- Measured shaking
- intensity VIII (ShakeMap)
- USGS impact alert
- green
- Nearest
- Imperial County, 22 km E
- Nearest mapped fault
- Brawley Seismic Zone, 1 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 324 days ago
Earthquake alerts for Westmorland, 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 light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.
At this magnitude and depth, people at rest would likely notice it out to about 184 km (114 mi) from the epicentre. In Westmorland, 3 km away, the estimate is intensity V (moderate). 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: Brawley 10 km, intensity IV · Calipatria 11 km, intensity IV · Imperial 23 km, intensity IV · El Centro 29 km, intensity IV · Holtville 33 km, intensity IV · Calexico 43 km, intensity III · Salton City 44 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 370 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.9 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 450× the energy of this one
- Mineral, Virginia 2011 M 5.8 20× the energy of this one
- Magna, Utah 2020 M 5.7 14× the energy of this one
- This earthquake M 4.9 about 370 tons of TNT
- Around the size people start to feel M 3.0 this one released 790× more
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 (31 mi) since our catalogue begins in 2016. The previous largest was M 4.6 on 2020-08-10.
Before 2016, the USGS record lists 38 earthquakes of M5 or more within 50 km; the five largest:
- 6.9 The 1940 Imperial Valley, California Earthquake · 31 km SE of this epicentre
- 6.6 The 1942 Fish Creek Mountains, California Earthquake · 20 km WSW of this epicentre
- 6.6 The 1968 Borrego Mountain, California Earthquake · 50 km WNW of this epicentre
- 6.6 The 1987 Superstition Hills, California Earthquake · 25 km W of this epicentre
- 6.4 The 1979 Imperial Valley Earthquake, California-Baja California · 48 km SSE 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 33.0547, -115.5907. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Imperial County, CA | 22 km (14 mi) | E | earthquakes near Imperial County |
| Riverside County, CA | 84 km (52 mi) | NNW | earthquakes near Riverside County |
| San Diego County, CA | 111 km (69 mi) | W | earthquakes near San Diego County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
60 earthquakes have been recorded within 50 km since this one.
- 2.6 4km ENE of Westmorland, CA
- 3.3 3km NE of Westmorland, CA
- 3.2 3km E of Westmorland, CA
- 3.4 3km NE of Westmorland, CA
- 2.2 4km ENE of Westmorland, CA
- 1.8 4km NE of Westmorland, CA
- 1.6 3km ESE of Westmorland, CA
- 1.8 1km NE of Westmorland, CA
- 1.8 4km E of Westmorland, CA
- 3.1 3km ENE of Westmorland, CA
- 2.7 4km NNE of Westmorland, CA
- 2.8 4km ENE of Westmorland, CA
- 4.1 4km NE of Westmorland, CA
- 2.5 4km ENE of Westmorland, CA
- 2.1 3km E of Westmorland, 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.