Earthquake near Challenge-Brownsville, CA

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. In Challenge-Brownsville, 9 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.

Earthquakes near other towns within 30 km: Lake Wildwood, Loma Rica, Penn Valley, Nevada City, Grass Valley, Oroville East.

How big was it?

This earthquake released about 14 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.

1. Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
2. Magna, Utah 2020 M 5.7 790,000× the energy of this one
3. Around the size people start to feel M 3.0 70× the energy of this one
4. This earthquake M 1.8 about 14 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

1. 5.9 West of Downieville, California · 23 km ENE of this epicentre Jun 23, 1909
2. 5.7 The 1975 Oroville, California Earthquake · 28 km W of this epicentre Aug 1, 1975
3. 5.2 4 km E of Palermo, California · 23 km WNW of this epicentre Aug 2, 1975
4. 5.1 5 km ENE of Palermo, California · 22 km WNW of this epicentre Aug 2, 1975
5. 5.0 Nevada County, California · 28 km E of this epicentre Mar 3, 1909

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 39.3897, -121.2297. Map © OpenStreetMap contributors.

Nearby places

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

27 earthquakes have been recorded within 50 km since this one.

1. 2.0 6 km E of Challenge-Brownsville, CA 06:19 UTC
2. 2.1 8 km WNW of La Porte, CA 19:25 UTC
3. 2.1 7 km ESE of Challenge-Brownsville, CA 06:29 UTC
4. 1.9 5 km WSW of Concow, CA 18:59 UTC
5. 1.8 8 km NNE of Oroville East, CA 07:09 UTC
6. 1.7 8 km NNE of Oroville East, CA 05:32 UTC
7. 2.1 12 km W of La Porte, CA 05:48 UTC
8. 1.6 Northern California 00:01 UTC
9. 2.1 10km N of Oroville, CA 19:59 UTC
10. 2.0 5km SSE of Oroville East, CA 02:41 UTC
11. 2.3 10km WNW of Little Grass Valley, CA 14:51 UTC
12. 4.2 5km S of Oroville East, CA 01:41 UTC
13. 2.2 9km E of Little Grass Valley, CA 13:48 UTC
14. 1.8 10km N of Oroville, CA 19:18 UTC
15. 2.0 10km N of Oroville, CA 19:59 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 15:37 UTC. 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.