QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

18km NE of San Martin, CA

· 49 km deep · released about 16 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Clara County 21 kmSanta Cruz County 53 kmStanislaus County 58 kmMerced County 65 kmAlameda County 66 kmSan Benito County 71 kmSan Joaquin County 85 kmSan Mateo County 85 kmContra Costa County 93 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
Magnitude
M 1.8 (md)
Depth
49 km below the surface
Felt
no reports yet
Nearest
Santa Clara County, 21 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2770 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

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.

  1. Mineral, Virginia 2011 M 5.8 970,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 680,000× the energy of this one
  3. Around the size people start to feel M 3.0 61× the energy of this one
  4. 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.

Where

Epicentre 37.1832, -121.4530. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Santa Clara County, CA 21 km (13 mi) ESE of here earthquakes near Santa Clara County
Santa Cruz County, CA 53 km (33 mi) ENE of here earthquakes near Santa Cruz County
Stanislaus County, CA 58 km (36 mi) SW of here earthquakes near Stanislaus County
Merced County, CA 65 km (40 mi) W of here earthquakes near Merced County
Alameda County, CA 66 km (41 mi) SE of here earthquakes near Alameda County
San Benito County, CA 71 km (44 mi) NNW of here earthquakes near San Benito County

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

Aftershocks so far

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

  1. 3.1 11km ENE of San Martin, CA
  2. 1.9 11km ENE of San Martin, CA
  3. 1.7 10km NNE of Tres Pinos, CA
  4. 1.8 4km ESE of Tres Pinos, CA
  5. 1.6 14km SSE of Livermore, CA
  6. 2.1 10km WSW of Ridgemark, CA
  7. 2.1 9km NNE of Alum Rock, CA
  8. 1.9 10km ENE of Morgan Hill, CA
  9. 1.9 3km NNW of Hollister, CA
  10. 1.7 7km WSW of Gilroy, CA
  11. 1.5 9km NNE of Alum Rock, CA
  12. 1.6 8km SE of Seven Trees, CA
  13. 1.8 7km WSW of Gilroy, CA
  14. 1.7 7km WSW of Gilroy, CA
  15. 2.5 12km NNE of Morgan Hill, 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.

For this area

The largest earthquake within 50 km in our catalogue was M 4.1 on 2017-10-10 — it released about 2,600 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

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