Earthquake · reviewed by a seismologist
M 1.8ml
Earthquake near Fontana, CA
No earthquake was likely felt in Fontana in the 24 hours to 9:03 am PST (17:03 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 8 km (5 mi) north of Fontana, CA, at 4:01 am PDT on 5 September 2020 (11:01 UTC), 9.5 km deep.
USGS: 7km NNE of Fontana, CA
6 km (4 mi) NNE of Fontana, CA · 91 km (56 mi) E of Los Angeles, CA
- When
- 4:01 am PDT on 5 September 2020 ()
- Where
- 8 km (5 mi) north of Fontana, CA · earthquakes near Fontana
- Magnitude
- M 1.8 (ml)
- Depth
- 9.5 km below the surface
- Felt
- no reports yet
- Nearest
- Orange County, 62 km SSW
- Nearest mapped fault
- Sierra Madre 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 2256 days ago
Earthquake alerts for Fontana, CA
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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 10 km (6 mi) from the epicentre. In Fontana, 8 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: Fontana 8 km, intensity II · Muscoy 9 km, intensity II · Rialto 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 15 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 1,000,000× the energy of this one
- Magna, Utah 2020 M 5.7 710,000× the energy of this one
- Around the size people start to feel M 3.0 63× the energy of this one
- This earthquake M 1.8 about 15 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 7,400 times the energy of this one.
Before 2016, the USGS record lists 10 earthquakes of M5 or more within 50 km; the five largest:
- 6.2 3 km SE of San Bernardino, California · 19 km ESE of this epicentre
- 5.6 7km ENE of Running Springs, CA · 38 km ENE of this epicentre
- 5.5 The 1990 Upland, California Earthquake · 24 km W of this epicentre
- 5.4 5km S of Chino Hills, CA · 38 km SW of this epicentre
- 5.3 Near San Bernardino, California · 32 km E 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 34.1618, -117.4410. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Orange County, CA | 62 km (39 mi) | SSW | earthquakes near Orange County |
| Los Angeles County, CA | 76 km (47 mi) | W | earthquakes near Los Angeles County |
| San Bernardino County, CA | 139 km (86 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.
- 1.5 3km WSW of Redlands, CA
- 1.5 2km NNW of Fontana, CA
- 1.6 2km W of Calimesa, CA
- 2.0 4km NNE of Walnut, CA
- 1.7 7km N of Fontana, CA
- 1.5 5km SE of Lytle Creek, CA
- 1.8 6km SSW of Calimesa, CA
- 1.6 15km NW of Rancho Cucamonga, CA
- 1.6 10km SSW of Calimesa, CA
- 2.6 6km NW of Corona, CA
- 1.6 6km NW of Corona, CA
- 1.9 6km NW of Corona, CA
- 1.5 4km SW of Redlands, CA
- 1.6 4km SW of Redlands, CA
- 1.5 13km NNE of Yucaipa, 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.