Earthquake · automatic estimate, may change
M 1.7md
Earthquake near San Ramon, CA
USGS: 2 km SW of San Ramon, CA
5 km (3 mi) W of San Ramon, CA · 37 km (23 mi) E of San Francisco, CA
- When
- 3:06 pm PDT on 28 September 2026 ()
- Where
- 2 km (1 mi) SW of San Ramon, CA · earthquakes near San Ramon
- Magnitude
- M 1.7 (md)
- Depth
- 8.3 km below the surface
- Felt
- no reports yet
- Nearest
- Alameda County, 15 km SSE
- Nearest mapped fault
- Calaveras fault, 3 km from its surface trace — near is not the same as on
- Status
- Automatic — a machine’s first estimate, which may change
USGS · last changed by USGS · we first saw it 4 days ago
A magnitude 1.7 earthquake was recorded 2 km (1 mi) SW of San Ramon, CA, at 3:06 pm PDT on 28 September 2026 (22:06 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.
Earthquakes near other towns within 30 km: Danville, Diablo, Dublin, Blackhawk, Alamo, Fairview.
How big was it?
This earthquake released about 10 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,500,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
- Around the size people start to feel M 3.0 95× the energy of this one
- This earthquake M 1.7 about 10 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 15,000 times the energy of this one.
Before 2016, the USGS record lists 8 earthquakes of M5 or more within 50 km; the five largest:
- 7.9 The 1906 San Francisco, California Earthquake · 49 km W of this epicentre
- 5.8 The 1980 Livermore, California Earthquake · 22 km ENE of this epicentre
- 5.7 15 km NE of East Foothills, California · 42 km SE of this epicentre
- 5.5 6 km NNE of East Foothills, California · 42 km SSE of this epicentre
- 5.4 9 km NE of Livermore, California · 25 km E 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 37.7643, -121.9942. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Alameda County, CA | 15 km (9 mi) | SSE | earthquakes near Alameda County |
| Contra Costa County, CA | 18 km (11 mi) | NNE | earthquakes near Contra Costa County |
| San Mateo County, CA | 51 km (32 mi) | SW | earthquakes near San Mateo County |
| Solano County, CA | 56 km (35 mi) | N | earthquakes near Solano County |
| Santa Clara County, CA | 66 km (41 mi) | SSE | earthquakes near Santa Clara County |
| San Joaquin County, CA | 66 km (41 mi) | ENE | earthquakes near San Joaquin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
2 earthquakes have been recorded within 50 km since this one.
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.