Earthquake · reviewed by a seismologist
M 2.1md
Earthquake near Castro Valley, CA
No earthquake was likely felt in Castro Valley in the 24 hours to 5:16 am PST (13:16 UTC). The last one was M 1.9, 10 km (6 mi) ESE, at 10:32 am PST on 2 November 2026, estimated intensity II (weak) in town. Every earthquake near Castro Valley
This page: a magnitude 2.1 earthquake was recorded in Castro Valley, CA, at 5:57 am PST on 1 February 2021 (13:57 UTC), 4.8 km deep. 12 people have reported feeling it to USGS.
USGS: 2km WNW of Castro Valley, CA
13 km (8 mi) SE of Oakland, CA · in San Leandro, CA
- When
- 5:57 am PST on 1 February 2021 ()
- Where
- in Castro Valley, CA · earthquakes near Castro Valley
- Magnitude
- M 2.1 (md)
- Depth
- 4.8 km below the surface
- Felt
- 12 reports · strongest reported intensity III
- Nearest
- Alameda County, 18 km ESE
- Nearest mapped fault
- Hayward fault, under 1 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 2106 days ago
Earthquake alerts for Castro Valley, CA
Get a notification in this browser when USGS records an earthquake near Castro Valley, 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 16 km (10 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: Castro Valley in town, intensity II · San Lorenzo 4 km, intensity II · Hayward 4 km, intensity II · San Leandro 5 km, intensity II · Union City 14 km, intensity II · San Ramon 15 km, intensity II · Dublin 15 km, intensity II · Alameda 16 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 37 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 410,000× the energy of this one
- Magna, Utah 2020 M 5.7 290,000× the energy of this one
- Around the size people start to feel M 3.0 26× the energy of this one
- This earthquake M 2.1 about 37 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 4,000 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 · 39 km W of this epicentre
- 5.8 The 1980 Livermore, California Earthquake · 34 km ENE of this epicentre
- 5.7 15 km NE of East Foothills, California · 44 km ESE of this epicentre
- 5.5 6 km NNE of East Foothills, California · 42 km SE of this epicentre
- 5.4 9 km NE of Livermore, California · 36 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 37.6987, -122.1070. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Alameda County, CA | 18 km (11 mi) | ESE | earthquakes near Alameda County |
| Contra Costa County, CA | 28 km (17 mi) | NNE | earthquakes near Contra Costa County |
| San Mateo County, CA | 39 km (24 mi) | SW | earthquakes near San Mateo County |
| Santa Clara County, CA | 65 km (40 mi) | SE | earthquakes near Santa Clara County |
| Solano County, CA | 65 km (40 mi) | NNE | earthquakes near Solano County |
| Marin County, CA | 68 km (43 mi) | NW | earthquakes near Marin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
53 earthquakes have been recorded within 50 km since this one.
- 1.5 0km NW of Danville, CA
- 1.6 4km NNW of Pacifica, CA
- 2.1 1km WNW of Danville, CA
- 2.8 2km N of Piedmont, CA
- 1.5 5km E of Vallejo, CA
- 1.7 7km W of Newark, CA
- 2.5 2km N of Piedmont, CA
- 1.8 3km WSW of Oakley, CA
- 1.8 3km S of Concord, CA
- 2.3 6km WSW of Colma, CA
- 2.2 14km SE of Livermore, CA
- 1.5 9km ENE of Milpitas, CA
- 2.1 3km WNW of Pacifica, CA
- 2.0 9km ENE of Milpitas, CA
- 2.3 14km SE of Livermore, 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.