Earthquake · reviewed by a seismologist
M 1.8ml
Earthquake near Fontana, CA
No earthquake was likely felt in Fontana in the 24 hours to 7:11 am PST (15:11 UTC). The last one was M 1.6, 5 km (3 mi) W, at 6:17 am PDT on 26 October 2026, estimated intensity II (weak) in town. Every earthquake near Fontana
This page: a magnitude 1.8 earthquake was recorded 12 km (8 mi) north-northeast of Fontana, CA, at 2:06 am PDT on 24 August 2021 (09:06 UTC), 12 km deep.
USGS: 3km SSE of Devore, CA
9 km (6 mi) N of Rialto, CA · 96 km (60 mi) ENE of Los Angeles, CA
- When
- 2:06 am PDT on 24 August 2021 ()
- Where
- 12 km (8 mi) north-northeast of Fontana, CA · earthquakes near Fontana
- Magnitude
- M 1.8 (ml)
- Depth
- 12 km below the surface
- Felt
- no reports yet
- Nearest
- Orange County, 68 km SSW
- Nearest mapped fault
- San Jacinto fault, 3 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 1906 days ago
Earthquake alerts for Fontana, CA
Get a notification in this browser when USGS records an earthquake near Fontana, CA. No account or email needed.
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 7 km (4 mi) from the epicentre. In Fontana, 12 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: Muscoy 7 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 17 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 5.8 900,000× the energy of this one
- Magna, Utah 2020 M 5.7 640,000× the energy of this one
- Around the size people start to feel M 3.0 57× the energy of this one
- This earthquake M 1.8 about 17 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 6,700 times the energy of this one.
Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:
- 6.2 3 km SE of San Bernardino, California · 17 km SE of this epicentre
- 5.6 7km ENE of Running Springs, CA · 33 km E of this epicentre
- 5.5 The 1990 Upland, California Earthquake · 29 km WSW of this epicentre
- 5.5 11km SSE of Big Bear Lake, California · 50 km E of this epicentre
- 5.4 5km S of Chino Hills, CA · 44 km SW 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 34.1978, -117.3915. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Orange County, CA | 68 km (42 mi) | SSW | earthquakes near Orange County |
| Los Angeles County, CA | 80 km (50 mi) | W | earthquakes near Los Angeles County |
| San Bernardino County, CA | 133 km (83 mi) | NE | earthquakes near San Bernardino County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
54 earthquakes have been recorded within 50 km since this one.
- 1.7 4km SE of Redlands, CA
- 1.5 4km SE of Home Gardens, CA
- 1.8 5km SSW of Redlands, CA
- 1.7 3km SSW of Calimesa, CA
- 2.0 3km SE of Loma Linda, CA
- 1.5 5km SE of Home Gardens, CA
- 1.5 2km E of Yucaipa, CA
- 2.5 6km E of Yucaipa, CA
- 1.6 5km NNE of Fontana, CA
- 2.1 3km SW of San Bernardino, CA
- 1.9 5km WSW of Devore, CA
- 1.6 3km E of Loma Linda, CA
- 2.0 4km SE of Home Gardens, CA
- 1.7 3km WSW of Yucaipa, CA
- 1.9 3km WNW 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.