Earthquake · reviewed by a seismologist
M 1.6md
Earthquake near San Ramon, CA
No earthquake was likely felt in San Ramon in the 24 hours to 2:57 am PST (10:57 UTC). The last one was M 2.1, 6 km (4 mi) NNE, at 7:18 am PDT on 31 October 2026, estimated intensity II (weak) in town; 1 felt report to USGS. Every earthquake near San Ramon
This page: a magnitude 1.6 earthquake was recorded in San Ramon, CA, at 5:21 am PST on 12 December 2019 (13:21 UTC), 10 km deep. 3 people have reported feeling it to USGS.
USGS: 2km SSE of San Ramon, CA
in San Ramon, CA · 39 km (24 mi) E of San Francisco, CA
- When
- 5:21 am PST on 12 December 2019 ()
- Where
- in San Ramon, CA · earthquakes near San Ramon
- Magnitude
- M 1.6 (md)
- Depth
- 10 km below the surface
- Felt
- 3 reports · strongest reported intensity II
- Nearest
- Alameda County, 14 km SSE
- Nearest mapped fault
- Pleasanton 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 2520 days ago
Earthquake alerts for San Ramon, CA
Get a notification in this browser when USGS records an earthquake near San Ramon, CA. No account or email needed.
Alerts are on for .
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 3 km (2 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. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 6.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,400,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,700,000× the energy of this one
- Around the size people start to feel M 3.0 150× the energy of this one
- This earthquake M 1.6 about 6.4 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 23,000 times the energy of this one.
Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:
- 5.8 The 1980 Livermore, California Earthquake · 20 km ENE of this epicentre
- 5.7 15 km NE of East Foothills, California · 41 km SE of this epicentre
- 5.5 6 km NNE of East Foothills, California · 41 km SSE of this epicentre
- 5.4 9 km NE of Livermore, California · 23 km E of this epicentre
- 5.3 The 1957 San Francisco, California Earthquake · 46 km WSW 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 37.7672, -121.9717. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Alameda County, CA | 14 km (9 mi) | SSE | earthquakes near Alameda County |
| Contra Costa County, CA | 17 km (11 mi) | N | earthquakes near Contra Costa County |
| San Mateo County, CA | 53 km (33 mi) | SW | earthquakes near San Mateo County |
| Solano County, CA | 56 km (35 mi) | N | earthquakes near Solano County |
| San Joaquin County, CA | 64 km (40 mi) | ENE | earthquakes near San Joaquin County |
| Santa Clara County, CA | 66 km (41 mi) | SSE | earthquakes near Santa Clara 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.
- 1.6 4km ENE of Walnut Creek, CA
- 2.1 10km SE of Livermore, CA
- 1.6 1km N of San Pablo, CA
- 2.0 12km SW of Byron, CA
- 1.7 1km NE of Diablo, CA
- 2.1 1km NE of Diablo, CA
- 1.8 0km E of Diablo, CA
- 1.5 0km E of Diablo, CA
- 1.7 2km ESE of Woodside, CA
- 1.5 2km WNW of Concord, CA
- 1.7 3km ENE of San Ramon, CA
- 1.7 9km NNE of Alum Rock, CA
- 2.9 5km NE of Alum Rock, CA
- 1.9 2km SE of Pacheco, CA
- 1.7 5km NW of Sunol, 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.