QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9mw

10km ENE of Morgan Hill, CA

· 5.3 km deep · released about 9.3 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Clara County 12 kmSanta Cruz County 43 kmAlameda County 61 kmStanislaus County 66 kmMerced County 75 kmSan Benito County 76 kmSan Mateo County 76 kmSan Joaquin County 88 kmContra Costa County 89 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 3.9 (mw)
Depth
5.3 km below the surface
Felt
2804 reports · strongest reported intensity V
Measured shaking
intensity V (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Santa Clara County, 12 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1693 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 2804 people have reported feeling it to USGS.

How big was it?

This earthquake released about 9.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 18,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 810× the energy of this one
  3. Magna, Utah 2020 M 5.7 580× the energy of this one
  4. This earthquake M 3.9 about 9.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 19× 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.

Where

Epicentre 37.1760, -121.5638. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Santa Clara County, CA 12 km (8 mi) ESE of here earthquakes near Santa Clara County
Santa Cruz County, CA 43 km (27 mi) ENE of here earthquakes near Santa Cruz County
Alameda County, CA 61 km (38 mi) SSE of here earthquakes near Alameda County
Stanislaus County, CA 66 km (41 mi) SW of here earthquakes near Stanislaus County
Merced County, CA 75 km (46 mi) W of here earthquakes near Merced County
San Benito County, CA 76 km (47 mi) NW 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

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

  1. 1.6 6km ENE of San Juan Bautista, CA
  2. 1.7 9km NNE of Alum Rock, CA
  3. 2.1 25km WSW of Westley, CA
  4. 2.9 5km NE of Alum Rock, CA
  5. 2.1 5km S of San Juan Bautista, CA
  6. 2.1 5km S of San Juan Bautista, CA
  7. 2.6 5km S of San Juan Bautista, CA
  8. 1.7 3km E of Aromas, CA
  9. 1.5 15km E of Seven Trees, CA
  10. 1.8 8km NE of Alum Rock, CA
  11. 2.3 16km N of Morgan Hill, CA
  12. 1.7 10km ESE of Gilroy, CA
  13. 1.6 9km NE of Alum Rock, CA
  14. 2.0 3km W of San Juan Bautista, CA
  15. 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.

For this area

The largest earthquake within 50 km in our catalogue was M 4.1 on 2017-10-10 — it released about 2.2 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.