QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9md

2km N of Castro Valley, CA

· 11 km deep · released about 22 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Alameda County 17 kmContra Costa County 26 kmSan Mateo County 41 kmSolano County 63 kmSanta Clara County 65 kmMarin County 69 kmSan Joaquin County 76 kmSanta Cruz County 78 kmSan Francisco County 83 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 1.9 (md)
Depth
11 km below the surface
Felt
2 reports · strongest reported intensity II
Nearest
Alameda County, 17 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1578 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage. 2 people have reported feeling it to USGS.

How big was it?

This earthquake released about 22 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 680,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 480,000× the energy of this one
  3. Around the size people start to feel M 3.0 43× the energy of this one
  4. This earthquake M 1.9 about 22 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.

Where

Epicentre 37.7087, -122.0887. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Alameda County, CA 17 km (11 mi) WNW of here earthquakes near Alameda County
Contra Costa County, CA 26 km (16 mi) SSW of here earthquakes near Contra Costa County
San Mateo County, CA 41 km (26 mi) NE of here earthquakes near San Mateo County
Solano County, CA 63 km (39 mi) SSW of here earthquakes near Solano County
Santa Clara County, CA 65 km (40 mi) NNW of here earthquakes near Santa Clara County
Marin County, CA 69 km (43 mi) ESE of here earthquakes near Marin County

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

Aftershocks so far

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

  1. 1.7 5km WSW of Colma, CA
  2. 2.2 9km NE of Milpitas, CA
  3. 1.8 3km NNE of San Leandro, CA
  4. 1.7 11km SE of Livermore, CA
  5. 1.5 6km S of Portola Valley, CA
  6. 1.8 12km SE of Livermore, CA
  7. 1.9 4km W of Pleasant Hill, CA
  8. 1.8 11km NE of Milpitas, CA
  9. 1.8 2km E of Walnut Creek, CA
  10. 1.5 4km WNW of Orinda, CA
  11. 1.6 6km WNW of Dublin, CA
  12. 1.7 3km ESE of Pacifica, CA
  13. 1.9 3km ESE of Pacifica, CA
  14. 1.8 3km ESE of Pacifica, CA
  15. 1.8 7km SSE of Portola Valley, 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 4.5 on 2019-10-15 — it released about 6,700 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.