Earthquake · reviewed by a seismologist
M 3.4mw
Earthquake near San Martin, CA
No earthquake was likely felt in San Martin in the 24 hours to 11:27 pm PST (07:27 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 3.4 earthquake was recorded 9 km (5 mi) east-northeast of San Martin, CA, at 11:40 am PDT on 26 October 2017 (18:40 UTC), 7.5 km deep. 271 people have reported feeling it to USGS.
USGS: 8 km ENE of San Martin, California
14 km (9 mi) NNE of Gilroy, CA · 32 km (20 mi) SE of San Jose, CA
- When
- 11:40 am PDT on 26 October 2017 ()
- Where
- 9 km (5 mi) east-northeast of San Martin, CA · earthquakes near San Martin
- Magnitude
- M 3.4 (mw)
- Depth
- 7.5 km below the surface
- Felt
- 271 reports · strongest reported intensity III
- Measured shaking
- intensity IV (ShakeMap)
- Nearest
- Santa Clara County, 19 km NW
- 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 3220 days ago
Earthquake alerts for San Martin, CA
Get a notification in this browser when USGS records an earthquake near San Martin, 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 San Martin, 9 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: Morgan Hill 12 km, intensity III · Gilroy 13 km, intensity III · Watsonville 31 km, intensity II · Hollister 32 km, intensity II · Prunedale 40 km, intensity II · San Jose 41 km, intensity II · Capitola 41 km, intensity II · Los Gatos 42 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 2.1 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 80,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 3,600× the energy of this one
- Magna, Utah 2020 M 5.7 2,500× the energy of this one
- This earthquake M 3.4 about 2.1 tons of TNT
- Around the size people start to feel M 3.0 this one released 4.4× 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 4.1 on 2017-10-10 — about 9.8 times the energy of this one.
Before 2016, the USGS record lists 28 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 · 10 km W of this epicentre
- 6.2 Near San Jose, California · 32 km NW of this epicentre
- 6.2 The 1984 Morgan Hill, California Earthquake · 25 km NNW of this epicentre
- 6.1 Near San Jose, California · 26 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 37.1203, -121.5235. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Santa Clara County, CA | 19 km (12 mi) | NW | earthquakes near Santa Clara County |
| Santa Cruz County, CA | 45 km (28 mi) | WSW | earthquakes near Santa Cruz County |
| Stanislaus County, CA | 67 km (42 mi) | NE | earthquakes near Stanislaus County |
| Alameda County, CA | 68 km (42 mi) | NNW | earthquakes near Alameda County |
| San Benito County, CA | 69 km (43 mi) | SE | earthquakes near San Benito 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
49 earthquakes have been recorded within 50 km since this one.
- 1.9 10km E of Alum Rock, CA
- 3.9 8km ENE of Alum Rock, CA
- 3.1 9km ENE of San Martin, CA
- 2.2 9km SSW of Tres Pinos, 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
- 2.0 7km SSE of Gilroy, CA
- 1.6 7km WSW of Gilroy, CA
- 3.0 11km SW of Ridgemark, CA
- 1.7 6km SSW of Ridgemark, CA
- 2.0 15km E of Seven Trees, CA
- 1.8 10km E of Alum Rock, CA
- 1.6 9km SSW of Tres Pinos, CA
- 1.7 3km E of Aromas, 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.