QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near Mountain House, CA

No earthquake was likely felt in Mountain House in the 24 hours to 9:15 am PST (17:15 UTC). The last one was M 3.5, 41 km (26 mi) S, at 7:21 am PDT on 27 September 2026, estimated intensity II (weak) in town; 8 felt reports to USGS. Every earthquake near Mountain House

This page: a magnitude 1.8 earthquake was recorded 5 km (3 mi) northwest of Mountain House, CA, at 6:46 pm PDT on 20 May 2019 (01:46 UTC), 12 km deep.

USGS: 5km NW of Mountain House, CA

62 km (38 mi) NNE of San Jose, CA · 15 km (9 mi) NW of Tracy, CA

6:46 pm PDT, May 20, 2019 · · 12 km deep · released about 17 lb of TNT

Every earthquake near Mountain House Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Joaquin County 30 kmContra Costa County 35 kmAlameda County 35 kmStanislaus County 58 kmSolano County 59 kmSanta Clara County 67 kmSacramento County 73 kmSan Mateo County 83 kmSanta Cruz 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
6:46 pm PDT on 20 May 2019 ()
Where
5 km (3 mi) northwest of Mountain House, CA · earthquakes near Mountain House
Magnitude
M 1.8 (md)
Depth
12 km below the surface
Felt
no reports yet
Nearest
San Joaquin County, 30 km ENE
Nearest mapped fault
Corral Hollow-Carnegie fault, 15 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 2732 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 6 km (4 mi) from the epicentre. In Mountain House, 5 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: Byron, Discovery Bay, Tracy, Brentwood, Knightsen, Livermore.

How big was it?

This earthquake released about 17 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 5.8 870,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 620,000× the energy of this one
  3. Around the size people start to feel M 3.0 55× the energy of this one
  4. This earthquake M 1.8 about 17 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.8 The 1980 Livermore, California Earthquake · 17 km W of this epicentre
  2. 5.7 15 km NE of East Foothills, California · 39 km SSW of this epicentre
  3. 5.5 6 km NNE of East Foothills, California · 46 km SSW of this epicentre
  4. 5.4 9 km NE of Livermore, California · 13 km SW of this epicentre
  5. 5.3 6 km E of East Foothills, California · 49 km SSW 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 37.8178, -121.5797. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Joaquin County, CA 30 km (19 mi) ENE earthquakes near San Joaquin County
Contra Costa County, CA 35 km (21 mi) WNW earthquakes near Contra Costa County
Alameda County, CA 35 km (22 mi) WSW earthquakes near Alameda County
Stanislaus County, CA 58 km (36 mi) ESE earthquakes near Stanislaus County
Solano County, CA 59 km (37 mi) NNW earthquakes near Solano County
Santa Clara County, CA 67 km (42 mi) S earthquakes near Santa Clara County

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

Aftershocks so far

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

  1. 1.6 3km SW of Clayton, CA
  2. 1.6 4km N of Dublin, CA
  3. 1.6 4km NNE of Dublin, CA
  4. 1.6 4km NNE of Dublin, CA
  5. 2.0 4km N of Dublin, CA
  6. 1.9 4km N of Dublin, CA
  7. 1.8 4km NNE of Dublin, CA
  8. 1.7 4km N of Dublin, CA
  9. 2.0 4km N of Dublin, CA
  10. 1.6 4km N of Dublin, CA
  11. 2.0 4km NNE of Dublin, CA
  12. 2.3 4km N of Dublin, CA
  13. 1.5 4km N of Dublin, CA
  14. 1.6 2km WNW of Pittsburg, CA
  15. 1.8 5km NNE 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.