Earthquake · reviewed by a seismologist
M 1.5ml
Earthquake near Rossmoor, CA
No earthquake was likely felt in Rossmoor in the 24 hours to 5:42 am PST (13:42 UTC). The last one was M 3.2, 9 km (6 mi) W, at 12:44 am PDT on 9 October 2026, estimated intensity III (weak) in town; 1,090 felt reports to USGS. Every earthquake near Rossmoor
This page: a magnitude 1.5 earthquake was recorded in Rossmoor, CA, at 5:53 am PST on 1 December 2021 (13:53 UTC), 12 km deep. 1 person has reported feeling it to USGS.
USGS: 1km SW of Rossmoor, CA
7 km (4 mi) E of Long Beach, CA · 40 km (25 mi) SE of Los Angeles, CA
- When
- 5:53 am PST on 1 December 2021 ()
- Where
- in Rossmoor, CA · earthquakes near Rossmoor
- Magnitude
- M 1.5 (ml)
- Depth
- 12 km below the surface
- Felt
- 1 report · strongest reported intensity II
- Nearest
- Orange County, 32 km ESE
- Nearest mapped fault
- Newport-Inglewood-Rose Canyon fault, 6 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 1806 days ago
Earthquake alerts for Rossmoor, 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 it was probably too small to be felt, even directly above it. 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: Los Alamitos, Seal Beach, Hawaiian Gardens, Cypress, Signal Hill, Westminster.
How big was it?
This earthquake released about 5.9 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,800,000× the energy of this one
- Around the size people start to feel M 3.0 160× the energy of this one
- This earthquake M 1.5 about 5.9 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 33,000 times the energy of this one.
Before 2016, the USGS record lists 11 earthquakes of M5 or more within 50 km; the five largest:
- 6.4 The 1933 Long Beach, California Earthquake · 19 km SSE of this epicentre
- 5.9 The 1987 Whittier Narrows, California Earthquake · 31 km N of this epicentre
- 5.4 5km S of Chino Hills, CA · 36 km ENE of this epicentre
- 5.3 2 km SSW of Santa Monica, California · 45 km WNW of this epicentre
- 5.3 7km W of Newport Beach, CA · 19 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 33.7787, -118.0950. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Orange County, CA | 32 km (20 mi) | ESE | earthquakes near Orange County |
| Los Angeles County, CA | 49 km (30 mi) | NNW | earthquakes near Los Angeles County |
| Ventura County, CA | 115 km (72 mi) | NW | earthquakes near Ventura County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
51 earthquakes have been recorded within 50 km since this one.
- 2.1 21km SSW of San Pedro, CA
- 1.5 3km ESE of Carson, CA
- 1.5 2km NE of La Habra, CA
- 1.6 1km NNE of Hollywood, CA
- 1.5 0km SSE of Hollywood, CA
- 2.1 0km WSW of View Park-Windsor Hills, CA
- 1.8 2km NW of Torrance, CA
- 1.9 3km NE of Yorba Linda, CA
- 2.3 3km ENE of Marina del Rey, CA
- 2.1 10km SE of San Pedro, CA
- 1.8 23km ENE of Avalon, CA
- 2.0 17km SSE of San Pedro, CA
- 1.7 10km SW of Laguna Beach, CA
- 2.0 21km S of San Pedro, CA
- 1.8 5km SSE of San Pedro, 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.