Earthquake · reviewed by a seismologist
M 2.1md
Earthquake near Fremont, CA
No earthquake was likely felt in Fremont in the 24 hours to 4:00 am PST (12:00 UTC). The last one was M 3.5, 49 km (31 mi) ESE, at 7:21 am PDT on 27 September 2026, estimated intensity II (weak) in town; 8 felt reports to USGS. Every earthquake near Fremont
This page: a magnitude 2.1 earthquake was recorded 9 km (5 mi) east-southeast of Fremont, CA, at 2:22 am PST on 8 February 2021 (10:22 UTC), 6.6 km deep. 2 people have reported feeling it to USGS.
USGS: 8km ESE of Fremont, CA
6 km (3 mi) NE of Fremont, CA
- When
- 2:22 am PST on 8 February 2021 ()
- Where
- 9 km (5 mi) east-southeast of Fremont, CA · earthquakes near Fremont
- Magnitude
- M 2.1 (md)
- Depth
- 6.6 km below the surface
- Felt
- 2 reports · strongest reported intensity IV
- Nearest
- Alameda County, 13 km N
- Nearest mapped fault
- Hayward fault, 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 2101 days ago
Earthquake alerts for Fremont, CA
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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. In Fremont, 9 km away, the estimate is intensity II (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: Fremont 9 km, intensity II · Milpitas 11 km, intensity II · Newark 13 km, intensity II · Union City 13 km, intensity II · Pleasanton 15 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 40 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 5.8 380,000× the energy of this one
- Magna, Utah 2020 M 5.7 270,000× the energy of this one
- Around the size people start to feel M 3.0 24× the energy of this one
- This earthquake M 2.1 about 40 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 3,700 times the energy of this one.
Before 2016, the USGS record lists 15 earthquakes of M5 or more within 50 km; the five largest:
- 6.2 Near San Jose, California · 27 km SSE of this epicentre
- 6.2 The 1984 Morgan Hill, California Earthquake · 31 km SE of this epicentre
- 6.1 Near San Jose, California · 37 km SSE of this epicentre
- 5.8 7 km NNW of Boulder Creek, California · 44 km SSW of this epicentre
- 5.8 The 1980 Livermore, California Earthquake · 36 km NNE 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 37.5282, -121.8938. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Alameda County, CA | 13 km (8 mi) | N | earthquakes near Alameda County |
| Santa Clara County, CA | 39 km (24 mi) | SSE | earthquakes near Santa Clara County |
| Contra Costa County, CA | 44 km (27 mi) | N | earthquakes near Contra Costa County |
| San Mateo County, CA | 44 km (27 mi) | WSW | earthquakes near San Mateo County |
| Santa Cruz County, CA | 58 km (36 mi) | S | earthquakes near Santa Cruz County |
| San Joaquin County, CA | 71 km (44 mi) | NE | earthquakes near San Joaquin 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.
- 2.2 5km WNW of Dublin, CA
- 2.0 6km WNW of Dublin, CA
- 2.2 5km NW of Dublin, CA
- 1.6 5km NW of Dublin, CA
- 1.9 6km SW of Clayton, CA
- 1.7 2km ESE of Berkeley, CA
- 1.8 2km ESE of Berkeley, CA
- 1.6 16km NE of Alum Rock, CA
- 1.5 4km NW of Dublin, CA
- 1.6 1km ENE of Alameda, CA
- 1.5 5km WSW of Lexington Hills, CA
- 2.3 15km E of Seven Trees, CA
- 1.5 0km NW of Danville, CA
- 2.5 10km E of Alum Rock, CA
- 2.1 1km WNW of Danville, 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.