Earthquake · reviewed by a seismologist
M 3.1mw
Earthquake near Dublin, CA
No earthquake was likely felt in Dublin in the 24 hours to 9:59 pm PST (05:59 UTC). The last one was M 1.9, 5 km (3 mi) SW, at 10:32 am PST on 2 November 2026, estimated intensity II (weak) in town. Every earthquake near Dublin
This page: a magnitude 3.1 earthquake was recorded 6 km (4 mi) west-northwest of Dublin, CA, at 5:09 pm PDT on 18 September 2021 (00:09 UTC), 7.1 km deep. 379 people have reported feeling it to USGS.
USGS: 6km WNW of Dublin, CA
7 km (4 mi) SW of San Ramon, CA · 38 km (24 mi) E of San Francisco, CA
- When
- 5:09 pm PDT on 18 September 2021 ()
- Where
- 6 km (4 mi) west-northwest of Dublin, CA · earthquakes near Dublin
- Magnitude
- M 3.1 (mw)
- Depth
- 7.1 km below the surface
- Felt
- 379 reports · strongest reported intensity III
- Nearest
- Alameda County, 11 km SE
- Nearest mapped fault
- Calaveras fault, 4 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 1805 days ago
Earthquake alerts for Dublin, CA
Get a notification in this browser when USGS records an earthquake near Dublin, 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 small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
At this magnitude and depth, people at rest would likely notice it out to about 41 km (25 mi) from the epicentre. In Dublin, 6 km away, the estimate is intensity III (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: Dublin 6 km, intensity III · San Ramon 6 km, intensity III · Castro Valley 9 km, intensity III · Hayward 10 km, intensity III · Danville 10 km, intensity III · Pleasanton 13 km, intensity III · San Lorenzo 14 km, intensity III · Alamo 14 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 250,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
- Magna, Utah 2020 M 5.7 7,900× the energy of this one
- This earthquake M 3.1 about 1,300 lb of TNT
- Around the size people start to feel M 3.0 this one released 1.4× more
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 110 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 · 23 km ENE of this epicentre
- 5.7 15 km NE of East Foothills, California · 39 km SE of this epicentre
- 5.5 6 km NNE of East Foothills, California · 38 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 37.7285, -121.9910. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Alameda County, CA | 11 km (7 mi) | SE | earthquakes near Alameda County |
| Contra Costa County, CA | 22 km (13 mi) | N | earthquakes near Contra Costa County |
| San Mateo County, CA | 48 km (30 mi) | SW | earthquakes near San Mateo County |
| Solano County, CA | 60 km (37 mi) | N | earthquakes near Solano County |
| Santa Clara County, CA | 62 km (39 mi) | SSE | earthquakes near Santa Clara County |
| San Joaquin County, CA | 67 km (42 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
59 earthquakes have been recorded within 50 km since this one.
- 1.8 1km NE of San Ramon, CA
- 2.0 1km NE of San Ramon, CA
- 2.0 1km NE of San Ramon, CA
- 1.5 2km NE of San Ramon, CA
- 3.0 1km NE of San Ramon, CA
- 1.7 1km NE of San Ramon, CA
- 2.3 1km NE of San Ramon, CA
- 2.1 1km NNE of San Ramon, CA
- 2.5 1km NE of San Ramon, CA
- 3.2 2km NE of San Ramon, CA
- 3.9 1km NE of San Ramon, CA
- 1.8 8km WSW of Mountain House, CA
- 2.0 5km E of Fremont, CA
- 2.3 1km W of Kensington, CA
- 2.6 1km W of Kensington, 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.