QuakeIndex

Earthquake · reviewed by a seismologist

M 2.3md

Earthquake near Interlaken, CA

No earthquake was likely felt in Interlaken in the 24 hours to 2:35 am PST (10:35 UTC). The last one was M 2.5, 15 km (9 mi) SE, at 6:10 am PDT on 26 October 2026, estimated intensity II (weak) in town; 6 felt reports to USGS. Every earthquake near Interlaken

This page: a magnitude 2.3 earthquake was recorded 4 km (3 mi) northeast of Interlaken, CA, at 3:46 pm PDT on 30 April 2018 (22:46 UTC), 7.2 km deep.

USGS: 4km NE of Interlaken, CA

9 km (6 mi) NE of Watsonville, CA · 37 km (23 mi) SSE of San Jose, CA

3:46 pm PDT, Apr 30, 2018 · · 7.2 km deep · released about 88 lb of TNT

10 km30 km60 km120 km N Santa Clara County 27 kmSanta Cruz County 28 kmSan Benito County 68 kmAlameda County 77 kmSan Mateo County 77 kmMonterey County 89 kmStanislaus County 89 kmMerced County 90 kmContra Costa County 107 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
3:46 pm PDT on 30 April 2018 ()
Where
4 km (3 mi) northeast of Interlaken, CA · earthquakes near Interlaken
Magnitude
M 2.3 (md)
Depth
7.2 km below the surface
Felt
no reports yet
Nearest
Santa Clara County, 27 km N
Nearest mapped fault
Sargent fault, 3 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 3117 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 19 km (12 mi) from the epicentre. In Interlaken, 4 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.

Likely felt in: Watsonville 9 km, intensity II · Gilroy 12 km, intensity II · Morgan Hill 17 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 88 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 170,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 120,000× the energy of this one
  3. Around the size people start to feel M 3.0 11× the energy of this one
  4. This earthquake M 2.3 about 88 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 730 times the energy of this one.

Before 2016, the USGS record lists 32 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 17 km WNW of this epicentre
  2. 6.5 Near Morgan Hill, California · 16 km NNE of this epicentre
  3. 6.3 22 km S of Davenport, California · 49 km WSW of this epicentre
  4. 6.2 Near San Jose, California · 37 km NNW of this epicentre
  5. 6.2 The 1984 Morgan Hill, California Earthquake · 37 km N 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 36.9798, -121.6992. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 27 km (17 mi) N earthquakes near Santa Clara County
Santa Cruz County, CA 28 km (17 mi) W earthquakes near Santa Cruz County
San Benito County, CA 68 km (42 mi) SE earthquakes near San Benito County
Alameda County, CA 77 km (48 mi) NNW earthquakes near Alameda County
San Mateo County, CA 77 km (48 mi) NW earthquakes near San Mateo County
Monterey County, CA 89 km (55 mi) SSE earthquakes near Monterey County

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

Aftershocks so far

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

  1. 1.6 6km NNW of Aromas, CA
  2. 2.1 12km SSE of Tres Pinos, CA
  3. 1.7 6km NNW of Aromas, CA
  4. 1.5 6km NNW of Aromas, CA
  5. 1.6 8km N of Boulder Creek, CA
  6. 2.8 6km SE of Tres Pinos, CA
  7. 1.5 9km E of Alum Rock, CA
  8. 2.6 9km E of Alum Rock, CA
  9. 2.0 15km E of Seven Trees, CA
  10. 1.7 10km NE of San Martin, CA
  11. 2.2 3km S of San Juan Bautista, CA
  12. 2.3 3km S of San Juan Bautista, CA
  13. 2.1 3km SSW of San Juan Bautista, CA
  14. 2.3 15km E of Seven Trees, CA
  15. 1.6 8km E of Alum Rock, 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.