Earthquake · reviewed by a seismologist
M 1.8md
Earthquake near San Jose, CA
No earthquake was likely felt in San Jose in the 24 hours to 3:54 am PST (11:54 UTC). The last one was M 2.6, 19 km (12 mi) E, at 12:38 pm PDT on 27 October 2026, estimated intensity II (weak) in town; 8 felt reports to USGS. Every earthquake near San Jose
This page: a magnitude 1.8 earthquake was recorded 16 km (10 mi) northeast of San Jose, CA, at 12:45 am PDT on 21 September 2017 (07:45 UTC), 8.2 km deep.
USGS: Northern California
18 km (11 mi) N of San Jose, CA · 9 km (6 mi) ENE of Milpitas, CA
- When
- 12:45 am PDT on 21 September 2017 ()
- Where
- 16 km (10 mi) northeast of San Jose, CA · earthquakes near San Jose
- Magnitude
- M 1.8 (md)
- Depth
- 8.2 km below the surface
- Felt
- no reports yet
- Nearest
- Alameda County, 24 km NNW
- Nearest mapped fault
- Calaveras 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 3338 days ago
Earthquake alerts for San Jose, 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 11 km (7 mi) from the epicentre. In San Jose, 16 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: Milpitas 11 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 16 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 930,000× the energy of this one
- Magna, Utah 2020 M 5.7 660,000× the energy of this one
- Around the size people start to feel M 3.0 59× the energy of this one
- This earthquake M 1.8 about 16 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
No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.
Before 2016, the USGS record lists 19 earthquakes of M5 or more within 50 km; the five largest:
- 6.9 The 1989 Loma Prieta, California Earthquake · 47 km S of this epicentre
- 6.5 Near Morgan Hill, California · 41 km SSE of this epicentre
- 6.2 Near San Jose, California · 17 km S of this epicentre
- 6.2 The 1984 Morgan Hill, California Earthquake · 19 km SSE of this epicentre
- 6.1 Near San Jose, California · 28 km S 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 37.4550, -121.7892. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Alameda County, CA | 24 km (15 mi) | NNW | earthquakes near Alameda County |
| Santa Clara County, CA | 27 km (17 mi) | SSE | earthquakes near Santa Clara County |
| San Mateo County, CA | 52 km (32 mi) | W | earthquakes near San Mateo County |
| Santa Cruz County, CA | 53 km (33 mi) | SSW | earthquakes near Santa Cruz County |
| Contra Costa County, CA | 54 km (33 mi) | NNW | earthquakes near Contra Costa County |
| San Joaquin County, CA | 70 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
53 earthquakes have been recorded within 50 km since this one.
- 1.6 2km E of Hayward, CA
- 2.0 20km W of Westley, CA
- 2.6 4km W of Cupertino, CA
- 2.5 22km W of Westley, CA
- 1.8 9km ENE of San Martin, CA
- 2.0 9km ENE of San Martin, CA
- 1.6 15km E of Seven Trees, CA
- 1.9 10km E of Alum Rock, CA
- 3.9 8km ENE of Alum Rock, CA
- 3.1 9km ENE of San Martin, CA
- 1.8 9km ENE of San Martin, CA
- 1.9 9km ENE of San Martin, CA
- 3.3 9km ENE of San Martin, CA
- 1.6 13km SSE of Livermore, CA
- 2.0 15km E of Seven Trees, 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.