Earthquake · reviewed by a seismologist
M 1.8md
Earthquake near San Martin, CA
No earthquake was likely felt in San Martin in the 24 hours to 1:39 pm PST (21:39 UTC). The last one was M 2.5, 17 km (10 mi) SE, at 7:27 pm PST on 1 November 2026, estimated intensity II (weak) in town; 2 felt reports to USGS. Every earthquake near San Martin
This page: a magnitude 1.8 earthquake was recorded 9 km (5 mi) east-northeast of San Martin, CA, at 6:01 am PST on 23 January 2023 (14:01 UTC), 6.0 km deep. 3 people have reported feeling it to USGS.
USGS: 9km ENE of San Martin, CA
13 km (8 mi) NNE of Gilroy, CA · 34 km (21 mi) SE of San Jose, CA
- When
- 6:01 am PST on 23 January 2023 ()
- Where
- 9 km (5 mi) east-northeast of San Martin, CA · earthquakes near San Martin
- Magnitude
- M 1.8 (md)
- Depth
- 6.0 km below the surface
- Felt
- 3 reports · strongest reported intensity III
- Nearest
- Santa Clara County, 20 km NW
- Nearest mapped fault
- Calaveras fault, 3 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 1386 days ago
Earthquake alerts for San Martin, 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 12 km (7 mi) from the epicentre. In San Martin, 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.
Earthquakes near other towns within 30 km: Gilroy, Morgan Hill, Interlaken, Aromas, Amesti, Corralitos.
How big was it?
This earthquake released about 15 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 1,000,000× the energy of this one
- Magna, Utah 2020 M 5.7 730,000× the energy of this one
- Around the size people start to feel M 3.0 65× the energy of this one
- This earthquake M 1.8 about 15 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 5.1 on 2022-10-25 — about 80,000 times the energy of this one.
Before 2016, the USGS record lists 29 earthquakes of M5 or more within 50 km; the five largest:
- 6.9 The 1989 Loma Prieta, California Earthquake · 33 km WSW of this epicentre
- 6.5 Near Morgan Hill, California · 11 km W of this epicentre
- 6.2 Near San Jose, California · 33 km NW of this epicentre
- 6.2 The 1984 Morgan Hill, California Earthquake · 27 km NNW of this epicentre
- 6.1 Near San Jose, California · 27 km WNW 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 37.1085, -121.5150. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Santa Clara County, CA | 20 km (12 mi) | NW | earthquakes near Santa Clara County |
| Santa Cruz County, CA | 45 km (28 mi) | WSW | earthquakes near Santa Cruz County |
| San Benito County, CA | 67 km (42 mi) | SE | earthquakes near San Benito County |
| Stanislaus County, CA | 68 km (42 mi) | NE | earthquakes near Stanislaus County |
| Alameda County, CA | 69 km (43 mi) | NNW | earthquakes near Alameda County |
| Merced County, CA | 71 km (44 mi) | E | earthquakes near Merced County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
56 earthquakes have been recorded within 50 km since this one.
- 1.7 7km ESE of Prunedale, CA
- 2.9 19km SSE of Livermore, CA
- 1.9 5km WSW of Tres Pinos, CA
- 2.0 10km S of Tres Pinos, CA
- 2.0 11km S of Tres Pinos, CA
- 2.8 11km S of Tres Pinos, CA
- 2.9 11km S of Tres Pinos, CA
- 2.3 11km S of Tres Pinos, CA
- 2.5 11km S of Tres Pinos, CA
- 2.8 13km SSW of Tres Pinos, CA
- 3.2 10km S of Tres Pinos, CA
- 3.2 10km S of Tres Pinos, CA
- 3.2 10km S of Tres Pinos, CA
- 2.5 2km ESE of Aromas, CA
- 2.4 12km NNE of Alum Rock, 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.