Earthquake near San Ramon, 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 9 km (6 mi) from the epicentre. 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: San Ramon in town, intensity II · Danville 5 km, intensity II · Alamo 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 13 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 5.7 810,000× the energy of this one
3. Around the size people start to feel M 3.0 72× the energy of this one
4. This earthquake M 1.8 about 13 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 4.5 on 2019-10-15 — about 11,000 times the energy of this one.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

1. 5.8 The 1980 Livermore, California Earthquake · 19 km ENE of this epicentre Jan 24, 1980
2. 5.7 15 km NE of East Foothills, California · 42 km SE of this epicentre Mar 31, 1986
3. 5.5 6 km NNE of East Foothills, California · 43 km SSE of this epicentre Oct 31, 2007
4. 5.4 9 km NE of Livermore, California · 24 km E of this epicentre Jan 27, 1980
5. 5.3 The 1957 San Francisco, California Earthquake · 47 km WSW of this epicentre Mar 22, 1957

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 37.7863, -121.9712. 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 8km NNE of Milpitas, CA 17:01 UTC
2. 1.8 19km SSE of Livermore, CA 21:22 UTC
3. 2.0 1km NW of Concord, CA 03:57 UTC
4. 1.6 2km NNE of Danville, CA 19:54 UTC
5. 2.3 5km E of Blackhawk, CA 06:46 UTC
6. 1.6 4km E of South San Francisco, CA 21:35 UTC
7. 1.9 3km ESE of Pacheco, CA 14:33 UTC
8. 1.9 8km E of Alum Rock, CA 05:57 UTC
9. 1.7 2km SSW of Blackhawk, CA 07:51 UTC
10. 1.5 5km WSW of Daly City, CA 07:30 UTC
11. 1.6 2km NE of Union City, CA 04:52 UTC
12. 1.8 3km ENE of San Leandro, CA 15:57 UTC
13. 2.9 3km ENE of San Leandro, CA 14:21 UTC
14. 1.6 2km ENE of Pacifica, CA 07:56 UTC
15. 3.2 2km NNE of San Leandro, CA 03:13 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 22:01 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.