Earthquake · reviewed by a seismologist
M 3.4mw
Earthquake near Milpitas, CA
No earthquake was likely felt in Milpitas in the 24 hours to 2:39 am PST (10:39 UTC). The last one was M 1.6, 9 km (5 mi) NNE, at 5:49 am PDT on 4 October 2026, estimated intensity II (weak) in town. Every earthquake near Milpitas
This page: a magnitude 3.4 earthquake was recorded 10 km (6 mi) northeast of Milpitas, CA, at 3:54 pm PDT on 27 September 2020 (22:54 UTC), 5.3 km deep. 1,065 people have reported feeling it to USGS.
USGS: 10km NE of Milpitas, CA
22 km (14 mi) N of San Jose, CA · 9 km (5 mi) NE of Milpitas, CA
- When
- 3:54 pm PDT on 27 September 2020 ()
- Where
- 10 km (6 mi) northeast of Milpitas, CA · earthquakes near Milpitas
- Magnitude
- M 3.4 (mw)
- Depth
- 5.3 km below the surface
- Felt
- 1,065 reports · strongest reported intensity IV
- Nearest
- Alameda County, 19 km NNW
- Nearest mapped fault
- Calaveras fault, 5 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 2158 days ago
Earthquake alerts for Milpitas, CA
Get a notification in this browser when USGS records an earthquake near Milpitas, 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 59 km (37 mi) from the epicentre. In Milpitas, 10 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: Milpitas 10 km, intensity III · Fremont 16 km, intensity III · San Jose 18 km, intensity III · Santa Clara 19 km, intensity III · Newark 19 km, intensity III · Pleasanton 19 km, intensity III · Union City 21 km, intensity III · Livermore 22 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 2 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 83,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 3,700× the energy of this one
- Magna, Utah 2020 M 5.7 2,600× the energy of this one
- This earthquake M 3.4 about 2 tons of TNT
- Around the size people start to feel M 3.0 this one released 4.3× 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 4.3 on 2019-07-16 — about 22 times the energy of this one.
Before 2016, the USGS record lists 17 earthquakes of M5 or more within 50 km; the five largest:
- 6.5 Near Morgan Hill, California · 45 km SSE of this epicentre
- 6.2 Near San Jose, California · 21 km S of this epicentre
- 6.2 The 1984 Morgan Hill, California Earthquake · 24 km SSE of this epicentre
- 6.1 Near San Jose, California · 33 km S of this epicentre
- 5.8 7 km NNW of Boulder Creek, California · 44 km SW 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 37.4917, -121.8247. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Alameda County, CA | 19 km (12 mi) | NNW | earthquakes near Alameda County |
| Santa Clara County, CA | 32 km (20 mi) | SSE | earthquakes near Santa Clara County |
| Contra Costa County, CA | 49 km (30 mi) | NNW | earthquakes near Contra Costa County |
| San Mateo County, CA | 49 km (30 mi) | W | earthquakes near San Mateo County |
| Santa Cruz County, CA | 56 km (35 mi) | SSW | earthquakes near Santa Cruz County |
| San Joaquin County, CA | 69 km (43 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.
- 1.5 8km ENE of Alum Rock, CA
- 1.7 10km NNE of San Martin, CA
- 1.6 9km NE of Milpitas, CA
- 1.7 7km N of Day Valley, CA
- 2.1 4km ESE of Hayward, CA
- 2.1 4km WNW of Dublin, CA
- 1.7 4km WNW of Dublin, CA
- 1.7 4km WNW of Dublin, CA
- 2.3 4km WNW of Dublin, CA
- 3.5 10km ENE of Morgan Hill, CA
- 3.7 10km ENE of Morgan Hill, CA
- 1.7 5km S of Blackhawk, CA
- 1.6 8km ENE of Alum Rock, CA
- 1.6 3km ESE of Highlands-Baywood Park, CA
- 2.2 11km NE of Milpitas, 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.