QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mw

Earthquake near Aromas, CA

Yes: an earthquake was likely felt in Aromas in the last 24 hours. M 2.6, in Aromas, at 11:40 am PST on 12 November 2026 (19:40 UTC); the estimated shaking in Aromas was intensity III (weak). Every earthquake near Aromas

This page: a magnitude 4.0 earthquake was recorded 3 km (2 mi) east-southeast of Aromas, CA, at 3:55 am PDT on 31 March 2017 (10:55 UTC), 6.2 km deep. 511 people have reported feeling it to USGS.

USGS: 2 km ESE of Aromas, California

15 km (9 mi) S of Gilroy, CA · 50 km (31 mi) SSE of San Jose, CA

3:55 am PDT, Mar 31, 2017 · · 6.2 km deep · released about 15 tons of TNT

Every earthquake near Aromas Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Cruz County 38 kmSanta Clara County 39 kmSan Benito County 56 kmMonterey County 76 kmMerced County 87 kmAlameda County 90 kmSan Mateo County 90 kmStanislaus County 93 kmContra Costa County 120 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
3:55 am PDT on 31 March 2017 ()
Where
3 km (2 mi) east-southeast of Aromas, CA · earthquakes near Aromas
Magnitude
M 4.0 (mw)
Depth
6.2 km below the surface
Felt
511 reports · strongest reported intensity VI
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Nearest
Santa Cruz County, 38 km WNW
Nearest mapped fault
San Andreas 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 3436 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 97 km (60 mi) from the epicentre. In Aromas, 3 km away, the estimate is intensity IV (light). 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: Prunedale 12 km, intensity IV · Watsonville 13 km, intensity IV · Gilroy 15 km, intensity III · Hollister 19 km, intensity III · Salinas 23 km, intensity III · Morgan Hill 28 km, intensity III · Capitola 32 km, intensity III · Live Oak 35 km, intensity III. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 11,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 500× the energy of this one
  3. Magna, Utah 2020 M 5.7 350× the energy of this one
  4. This earthquake M 4.0 about 15 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 32× 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 4.2 on 2016-07-19 — about 2.1 times the energy of this one.

Before 2016, the USGS record lists 30 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 29 km NW of this epicentre
  2. 6.5 Near Morgan Hill, California · 26 km N of this epicentre
  3. 6.2 Near San Jose, California · 50 km NNW of this epicentre
  4. 6.2 The 1984 Morgan Hill, California Earthquake · 48 km N of this epicentre
  5. 6.1 Near San Jose, California · 39 km NNW 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 36.8777, -121.6142. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Cruz County, CA 38 km (24 mi) WNW earthquakes near Santa Cruz County
Santa Clara County, CA 39 km (24 mi) N earthquakes near Santa Clara County
San Benito County, CA 56 km (35 mi) ESE earthquakes near San Benito County
Monterey County, CA 76 km (47 mi) SSE earthquakes near Monterey County
Merced County, CA 87 km (54 mi) ENE earthquakes near Merced County
Alameda County, CA 90 km (56 mi) NNW earthquakes near Alameda County

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

Aftershocks so far

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

  1. 1.8 22 km NNE of Soledad, California
  2. 1.8 13 km S of Tres Pinos, California
  3. 2.5 13 km N of Morgan Hill, California
  4. 1.5 13 km S of Tres Pinos, California
  5. 1.6 6 km S of Gilroy, California
  6. 2.4 7 km ENE of Gilroy, California
  7. 2.1 17 km SSE of Tres Pinos, California
  8. 1.9 17 km SSE of Tres Pinos, California
  9. 2.4 16 km N of Morgan Hill, California
  10. 2.6 9 km S of Tres Pinos, California
  11. 2.5 22 km NNE of Soledad, California
  12. 2.1 8 km SSW of Tres Pinos, California
  13. 2.3 11 km ESE of Gilroy, California
  14. 2.0 10 km ESE of Gilroy, California
  15. 3.2 10 km ESE of Gilroy, California

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.