Earthquake · reviewed by a seismologist
M 3.5ml
Earthquake near Willowbrook, CA
No earthquake was likely felt in Willowbrook in the 24 hours to 3:54 am PST (11:54 UTC). The last one was M 1.8, 4 km (2 mi) SW, at 2:31 pm PDT on 31 October 2026, estimated intensity II (weak) in town. Every earthquake near Willowbrook
This page: a magnitude 3.5 earthquake was recorded in Willowbrook, CA, at 8:31 am PST on 20 January 2021 (16:31 UTC), 20 km deep. 1,573 people have reported feeling it to USGS.
USGS: 2km W of Willowbrook, CA
17 km (11 mi) SE of Los Angeles, CA · in Gardena, CA
- When
- 8:31 am PST on 20 January 2021 ()
- Where
- in Willowbrook, CA · earthquakes near Willowbrook
- Magnitude
- M 3.5 (ml)
- Depth
- 20 km below the surface
- Felt
- 1,573 reports · strongest reported intensity III
- Measured shaking
- intensity III (ShakeMap)
- Nearest
- Los Angeles County, 31 km N
- Nearest mapped fault
- Newport-Inglewood-Rose Canyon fault, 5 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 1022 days ago
Earthquake alerts for Willowbrook, 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 small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
At this magnitude and depth, people at rest would likely notice it out to about 62 km (39 mi) from the epicentre. 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: Willowbrook in town, intensity III · Westmont 4 km, intensity III · Gardena 5 km, intensity III · Compton 5 km, intensity III · Lynwood 6 km, intensity III · Florence-Graham 6 km, intensity III · South Gate 7 km, intensity III · Hawthorne 7 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 2.9 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.5 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 59,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 2,600× the energy of this one
- Magna, Utah 2020 M 5.7 1,900× the energy of this one
- This earthquake M 3.5 about 2.9 tons of TNT
- Around the size people start to feel M 3.0 this one released 6× 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 since 2016 was M 4.5 on 2020-09-19 — about 34 times the energy of this one.
Before 2016, the USGS record lists 17 earthquakes of M5 or more within 50 km; the five largest:
- 6.7 Northridge, California, earthquake · 41 km NW of this epicentre
- 6.4 The 1933 Long Beach, California Earthquake · 41 km SE of this epicentre
- 5.9 The 1987 Whittier Narrows, California Earthquake · 24 km NE of this epicentre
- 5.9 1km ENE of Granada Hills, California · 45 km NNW of this epicentre
- 5.8 The 1991 Sierra Madre, California Earthquake · 47 km NNE 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 33.9187, -118.2717. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Los Angeles County, CA | 31 km (19 mi) | N | earthquakes near Los Angeles County |
| Orange County, CA | 53 km (33 mi) | ESE | earthquakes near Orange County |
| Ventura County, CA | 93 km (58 mi) | WNW | earthquakes near Ventura County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
56 earthquakes have been recorded within 50 km since this one.
- 1.6 1km SW of Inglewood, CA
- 2.0 1km WSW of Inglewood, CA
- 2.0 1km E of Lennox, CA
- 1.8 1km NNE of Lennox, CA
- 1.5 1km NW of Inglewood, CA
- 1.6 1km WSW of Inglewood, CA
- 2.3 1km ENE of Lennox, CA
- 1.8 1km S of Inglewood, CA
- 1.6 2km ENE of Lennox, CA
- 2.4 1km SSE of Inglewood, CA
- 2.3 2km E of Lennox, CA
- 1.9 1km SSE of Inglewood, CA
- 1.5 1km SE of Inglewood, CA
- 1.6 1km ESE of Inglewood, CA
- 1.7 1km WSW of Inglewood, 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.