QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5md

Earthquake near San Lorenzo, CA

No earthquake was likely felt in San Lorenzo in the 24 hours to 11:41 pm PST (07:41 UTC). The last one was M 2.4, 19 km (12 mi) ENE, at 4:29 pm PDT on 19 October 2026, estimated intensity II (weak) in town; 5 felt reports to USGS. Every earthquake near San Lorenzo

This page: a magnitude 1.5 earthquake was recorded in San Lorenzo, CA, at 3:39 am PDT on 3 September 2018 (10:39 UTC), 7.8 km deep.

USGS: 2km WSW of San Lorenzo, CA

13 km (8 mi) SE of Oakland, CA · in San Leandro, CA

3:39 am PDT, Sep 3, 2018 · · 7.8 km deep · released about 5.4 lb of TNT

10 km30 km60 km120 km N Alameda County 21 kmContra Costa County 32 kmSan Mateo County 35 kmSanta Clara County 65 kmMarin County 67 kmSolano County 68 kmSanta Cruz County 75 kmSan Francisco County 78 kmSan Joaquin County 82 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
3:39 am PDT on 3 September 2018 ()
Where
in San Lorenzo, CA · earthquakes near San Lorenzo
Magnitude
M 1.5 (md)
Depth
7.8 km below the surface
Felt
no reports yet
Nearest
Alameda County, 21 km E
Nearest mapped fault
Hayward fault, 4 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 2991 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. 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: San Lorenzo in town, intensity II · San Leandro 5 km, intensity II · Castro Valley 5 km, intensity II · Hayward 6 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 5.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,800,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 2,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 180× the energy of this one
  4. This earthquake M 1.5 about 5.4 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 4.4 on 2018-01-04 — about 21,000 times the energy of this one.

Before 2016, the USGS record lists 8 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.9 The 1906 San Francisco, California Earthquake · 37 km WNW of this epicentre
  2. 5.8 The 1980 Livermore, California Earthquake · 38 km ENE of this epicentre
  3. 5.7 15 km NE of East Foothills, California · 46 km ESE of this epicentre
  4. 5.5 6 km NNE of East Foothills, California · 42 km SE of this epicentre
  5. 5.4 9 km NE of Livermore, California · 39 km ENE 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 37.6777, -122.1442. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Alameda County, CA 21 km (13 mi) E earthquakes near Alameda County
Contra Costa County, CA 32 km (20 mi) NNE earthquakes near Contra Costa County
San Mateo County, CA 35 km (22 mi) SW earthquakes near San Mateo County
Santa Clara County, CA 65 km (40 mi) SE earthquakes near Santa Clara County
Marin County, CA 67 km (42 mi) NW earthquakes near Marin County
Solano County, CA 68 km (42 mi) NNE earthquakes near Solano 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. 2.4 1km NW of Crockett, CA
  2. 1.6 8km NE of Alum Rock, CA
  3. 1.6 11km S of Portola Valley, CA
  4. 1.7 6km NE of Blackhawk, CA
  5. 1.7 3km S of Loyola, CA
  6. 1.6 2km NW of Crockett, CA
  7. 2.7 2km NW of Crockett, CA
  8. 3.5 2km NW of Crockett, CA
  9. 2.0 4km E of El Sobrante, CA
  10. 1.6 6km WNW of Mountain House, CA
  11. 1.7 4km SSW of Los Altos Hills, CA
  12. 2.8 6km WNW of Mountain House, CA
  13. 1.6 2km NW of Pacifica, CA
  14. 2.5 3km ESE of San Leandro, CA
  15. 1.5 16km SSE of Livermore, 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.