Earthquake · reviewed by a seismologist
M 3.7mw
Earthquake near Fontana, CA
No earthquake was likely felt in Fontana in the 24 hours to 5:56 am PST (13:56 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 3.7 earthquake was recorded 25 km (15 mi) north-northwest of Fontana, CA, at 2:00 am PDT on 6 August 2025 (09:00 UTC), 12 km deep. 647 people have reported feeling it to USGS.
USGS: 6 km N of Lytle Creek, CA
91 km (56 mi) ENE of Los Angeles, CA · 19 km (12 mi) WSW of Hesperia, CA
- When
- 2:00 am PDT on 6 August 2025 ()
- Where
- 25 km (15 mi) north-northwest of Fontana, CA · earthquakes near Fontana
- Magnitude
- M 3.7 (mw)
- Depth
- 12 km below the surface
- Felt
- 647 reports · strongest reported intensity IV
- Measured shaking
- intensity IV (ShakeMap)
- Nearest
- Los Angeles County, 72 km W
- Nearest mapped fault
- San Andreas fault, 2 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 383 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 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 72 km (45 mi) from the epicentre. In Fontana, 25 km away, the estimate is intensity III (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 14 km, intensity III · Phelan 15 km, intensity III · Hesperia 22 km, intensity III · Muscoy 22 km, intensity III · Rancho Cucamonga 25 km, intensity III · Fontana 25 km, intensity III · Rialto 25 km, intensity III · Upland 28 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 4.7 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.7 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 36,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 1,600× the energy of this one
- Magna, Utah 2020 M 5.7 1,100× the energy of this one
- This earthquake M 3.7 about 4.7 tons of TNT
- Around the size people start to feel M 3.0 this one released 9.8× 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 4.4 on 2018-08-29 — about 12 times the energy of this one.
Before 2016, the USGS record lists 8 earthquakes of M5 or more within 50 km; the five largest:
- 6.2 3 km SE of San Bernardino, California · 33 km SE of this epicentre
- 5.8 The 1991 Sierra Madre, California Earthquake · 46 km W of this epicentre
- 5.6 7km ENE of Running Springs, CA · 42 km E of this epicentre
- 5.5 The 1990 Upland, California Earthquake · 26 km SW of this epicentre
- 5.4 5km S of Chino Hills, CA · 47 km SSW 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 34.3107, -117.4920. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Los Angeles County, CA | 72 km (45 mi) | W | earthquakes near Los Angeles County |
| Orange County, CA | 75 km (47 mi) | SSW | earthquakes near Orange County |
| Kern County, CA | 161 km (100 mi) | NW | earthquakes near Kern County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
47 earthquakes have been recorded within 50 km since this one.
- 1.7 6 km W of Yucaipa, CA
- 1.8 3 km WSW of Fontana, CA
- 1.7 0 km NW of Loma Linda, CA
- 2.3 2 km NNW of Loma Linda, CA
- 2.6 5 km SSE of Mentone, CA
- 1.6 7 km NNE of Running Springs, CA
- 2.1 4 km S of Redlands, CA
- 1.6 2 km NNE of Lake Arrowhead, CA
- 2.2 2 km NNE of Lake Arrowhead, CA
- 2.0 2 km NNE of Lake Arrowhead, CA
- 2.4 5 km NW of Rialto, CA
- 1.6 8 km SSE of Redlands, CA
- 1.7 7 km SSE of Lytle Creek, CA
- 2.1 6 km SSW of Redlands, CA
- 1.7 2 km W of Devore, 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.