Earthquake near Fontana, CA

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 15 km (9 mi) from the epicentre. In Fontana, 5 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 5 km, intensity II · Rialto 8 km, intensity II · Bloomington 9 km, intensity II · Muscoy 11 km, intensity II · Rancho Cucamonga 13 km, intensity II · Glen Avon 13 km, intensity II · Colton 15 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 47 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 320,000× the energy of this one
2. Magna, Utah 2020 M 5.7 230,000× the energy of this one
3. Around the size people start to feel M 3.0 20× the energy of this one
4. This earthquake M 2.1 about 47 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 2,400 times the energy of this one.

Before 2016, the USGS record lists 12 earthquakes of M5 or more within 50 km; the five largest:

1. 6.2 3 km SE of San Bernardino, California · 19 km ESE of this epicentre Jul 23, 1923
2. 6.0 The 1910 Lake Elsinore, California Earthquake · 48 km S of this epicentre May 15, 1910
3. 5.6 7km ENE of Running Springs, CA · 40 km ENE of this epicentre Oct 16, 1999
4. 5.5 The 1990 Upland, California Earthquake · 22 km W of this epicentre Feb 28, 1990
5. 5.4 5km S of Chino Hills, CA · 35 km SW of this epicentre Jul 29, 2008

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 34.1293, -117.4572. Map © OpenStreetMap contributors.

Nearby places

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. 1.6 3 km S of Fontana, CA 00:04 UTC
2. 1.1 13 km NE of Yucaipa, CA 16:57 UTC
3. 0.9 2 km ESE of Loma Linda, CA 14:45 UTC
4. 0.3 6 km E of Calimesa, CA 13:50 UTC
5. 0.9 2 km E of Loma Linda, CA 12:54 UTC
6. 1.1 3 km S of Fontana, CA 03:06 UTC
7. 1.1 1 km S of Loma Linda, CA 07:14 UTC
8. 1.0 2 km NNE of Loma Linda, CA 03:25 UTC
9. 1.5 2 km NE of Colton, CA 17:50 UTC
10. 0.9 2 km N of Loma Linda, CA 14:08 UTC
11. 0.8 4 km SSW of Redlands, CA 06:55 UTC
12. 1.0 4 km SE of Loma Linda, CA 06:18 UTC
13. 1.9 5 km ESE of Yucaipa, CA 05:59 UTC
14. 0.9 5 km SSW of Redlands, CA 00:51 UTC
15. 1.5 7 km SSE of Home Gardens, CA 21:51 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 08:37 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

Revisions

USGS refines a solution as more stations report. Every change we have seen is listed here.

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.