Earthquake · reviewed by a seismologist
M 1.6ml
Earthquake near Fontana, CA
No earthquake was likely felt in Fontana in the 24 hours to 5:18 am PST (13:18 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 1.6 earthquake was recorded 6 km (4 mi) north-northwest of Fontana, CA, at 9:47 am PST on 20 December 2021 (17:47 UTC), 7.0 km deep.
USGS: 4km N of Fontana, CA
in Fontana, CA · 88 km (55 mi) E of Los Angeles, CA
- When
- 9:47 am PST on 20 December 2021 ()
- Where
- 6 km (4 mi) north-northwest of Fontana, CA · earthquakes near Fontana
- Magnitude
- M 1.6 (ml)
- Depth
- 7.0 km below the surface
- Felt
- no reports yet
- Nearest
- Orange County, 59 km SSW
- Nearest mapped fault
- Sierra Madre 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 1788 days ago
Earthquake alerts for Fontana, CA
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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 9 km (6 mi) from the epicentre. In Fontana, 6 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 6 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 7.3 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,100,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,500,000× the energy of this one
- Around the size people start to feel M 3.0 130× the energy of this one
- This earthquake M 1.6 about 7.3 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 15,000 times the energy of this one.
Before 2016, the USGS record lists 12 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
- 6.0 The 1910 Lake Elsinore, California Earthquake · 49 km S of this epicentre
- 5.6 7km ENE of Running Springs, CA · 40 km ENE of this epicentre
- 5.5 The 1990 Upland, California Earthquake · 22 km W of this epicentre
- 5.4 5km S of Chino Hills, CA · 35 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 34.1382, -117.4617. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Orange County, CA | 59 km (37 mi) | SSW | earthquakes near Orange County |
| Los Angeles County, CA | 74 km (46 mi) | W | earthquakes near Los Angeles County |
| San Bernardino County, CA | 142 km (88 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 4km SE of Redlands, CA
- 1.9 6km SSE of Lytle Creek, CA
- 1.5 9km NE of Lake Arrowhead, CA
- 1.7 4km SSE of Home Gardens, CA
- 2.1 1km ENE of Yucaipa, CA
- 1.5 2km NW of Loma Linda, CA
- 1.8 3km SSW of San Bernardino, CA
- 1.6 10km NE of Lake Arrowhead, CA
- 1.5 3km ESE of Loma Linda, CA
- 2.0 7km NE of Lake Arrowhead, CA
- 1.7 10km WNW of Big Bear Lake, CA
- 1.7 10km WNW of Big Bear Lake, CA
- 1.8 8km N of Glendora, CA
- 2.6 2km S of Redlands, CA
- 1.5 4km SSW of Redlands, 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.