Earthquake · reviewed by a seismologist
M 1.8ml
Earthquake near Wrightwood, CA
No earthquake was likely felt in Wrightwood in the 24 hours to 7:05 pm PST (03:05 UTC). The last one was M 1.7, 5 km (3 mi) NW, at 6:36 pm PDT on 22 October 2026, estimated intensity II (weak) in town. Every earthquake near Wrightwood
This page: a magnitude 1.8 earthquake was recorded 4 km (3 mi) north-northwest of Wrightwood, CA, at 8:10 pm PDT on 22 April 2021 (03:10 UTC), 7.0 km deep. 2 people have reported feeling it to USGS.
USGS: 4km NNW of Wrightwood, CA
81 km (50 mi) ENE of Los Angeles, CA · 30 km (19 mi) NNW of Rancho Cucamonga, CA
- When
- 8:10 pm PDT on 22 April 2021 ()
- Where
- 4 km (3 mi) north-northwest of Wrightwood, CA · earthquakes near Wrightwood
- Magnitude
- M 1.8 (ml)
- Depth
- 7.0 km below the surface
- Felt
- 2 reports · strongest reported intensity III
- Nearest
- Los Angeles County, 60 km WSW
- Nearest mapped fault
- San Andreas fault, 4 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 2030 days ago
Earthquake alerts for Wrightwood, 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 11 km (7 mi) from the epicentre. In Wrightwood, 4 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: Wrightwood 4 km, intensity II · Phelan 9 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 14 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.
- Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
- Magna, Utah 2020 M 5.7 760,000× the energy of this one
- Around the size people start to feel M 3.0 68× the energy of this one
- This earthquake M 1.8 about 14 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 4.4 on 2018-08-29 — about 7,900 times the energy of this one.
Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:
- 6.2 3 km SE of San Bernardino, California · 50 km SE of this epicentre
- 5.8 The 1991 Sierra Madre, California Earthquake · 34 km WSW of this epicentre
- 5.5 The 1990 Upland, California Earthquake · 28 km S of this epicentre
- 5.2 3km W of Lytle Creek, CA · 19 km SE 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 34.3933, -117.6568. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Los Angeles County, CA | 60 km (37 mi) | WSW | earthquakes near Los Angeles County |
| Orange County, CA | 81 km (50 mi) | S | earthquakes near Orange County |
| Kern County, CA | 144 km (90 mi) | NW | earthquakes near Kern County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
41 earthquakes have been recorded within 50 km since this one.
- 1.6 4km N of Rancho Cucamonga, CA
- 1.5 5km NNE of Fontana, CA
- 1.8 1km NNW of La Puente, CA
- 2.5 3km WSW of Fontana, CA
- 1.6 5km WNW of Muscoy, CA
- 1.6 2km ENE of Colton, CA
- 2.5 4km SE of Ontario, CA
- 2.0 9km WSW of Lytle Creek, CA
- 1.5 7km NW of Rancho Cucamonga, CA
- 1.5 5km NW of Fontana, CA
- 1.8 5km NNW of Fontana, CA
- 1.9 6km SW of Fontana, CA
- 1.9 6km S of Lytle Creek, CA
- 1.7 5km SW of Fontana, CA
- 3.4 4km NNW of Fontana, 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.