QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

Earthquake near San Martin, CA

No earthquake was likely felt in San Martin in the 24 hours to 6:59 am PST (14:59 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 1.6 earthquake was recorded 9 km (6 mi) east of San Martin, CA, at 1:49 pm PDT on 30 May 2018 (20:49 UTC), 8.7 km deep. 1 person has reported feeling it to USGS.

USGS: 9km E of San Martin, CA

13 km (8 mi) NNE of Gilroy, CA · 35 km (22 mi) SE of San Jose, CA

1:49 pm PDT, May 30, 2018 · · 8.7 km deep · released about 8.7 lb of TNT

10 km30 km60 km120 km N Santa Clara County 21 kmSanta Cruz County 45 kmSan Benito County 66 kmStanislaus County 68 kmMerced County 70 kmAlameda County 70 kmSan Mateo County 84 kmSan Joaquin County 95 kmMonterey County 97 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
1:49 pm PDT on 30 May 2018 ()
Where
9 km (6 mi) east of San Martin, CA · earthquakes near San Martin
Magnitude
M 1.6 (md)
Depth
8.7 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Santa Clara County, 21 km NW
Nearest mapped fault
Calaveras fault, 4 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 3088 days ago

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 8 km (5 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, San Juan Bautista.

How big was it?

This earthquake released about 8.7 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,700,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,200,000× the energy of this one
  3. Around the size people start to feel M 3.0 110× the energy of this one
  4. This earthquake M 1.6 about 8.7 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 4.2 on 2016-07-19 — about 7,400 times the energy of this one.

Before 2016, the USGS record lists 29 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 34 km WSW of this epicentre
  2. 6.5 Near Morgan Hill, California · 12 km W of this epicentre
  3. 6.2 Near San Jose, California · 34 km NW of this epicentre
  4. 6.2 The 1984 Morgan Hill, California Earthquake · 28 km NNW of this epicentre
  5. 6.1 Near San Jose, California · 28 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 37.1010, -121.5078. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 21 km (13 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 66 km (41 mi) SE earthquakes near San Benito County
Stanislaus County, CA 68 km (42 mi) NE earthquakes near Stanislaus County
Merced County, CA 70 km (44 mi) E earthquakes near Merced County
Alameda County, CA 70 km (44 mi) NNW earthquakes near Alameda County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

52 earthquakes have been recorded within 50 km since this one.

  1. 1.7 6km SW of Ridgemark, CA
  2. 2.2 9km NE of San Martin, CA
  3. 2.1 15km E of Seven Trees, CA
  4. 2.7 5km ESE of Aromas, CA
  5. 1.5 8km ENE of Gilroy, CA
  6. 2.0 5km ESE of Aromas, CA
  7. 1.6 10km NNE of Hollister, CA
  8. 2.7 6km SW of Ridgemark, CA
  9. 1.6 12km NNW of Hollister, CA
  10. 1.9 9km E of Gilroy, CA
  11. 2.0 9km ENE of San Martin, CA
  12. 1.6 6km WSW of Ridgemark, CA
  13. 1.6 20km ENE of Tres Pinos, CA
  14. 2.3 4km W of Hollister, CA
  15. 2.5 9km NE of Gilroy, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.