QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

2 km W of Saint Helena, California

· 9.9 km deep · released about 17 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Napa County 15 kmSonoma County 38 kmYolo County 55 kmSolano County 55 kmMarin County 55 kmLake County 70 kmColusa County 78 kmContra Costa County 81 kmSutter County 90 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 1.8 (md)
Depth
9.9 km below the surface
Felt
no reports yet
Nearest
Napa County, 15 km E
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3303 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

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.

Where

Epicentre 38.5053, -122.4933. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Napa County, CA 15 km (9 mi) W of here earthquakes near Napa County
Sonoma County, CA 38 km (23 mi) E of here earthquakes near Sonoma County
Yolo County, CA 55 km (34 mi) WSW of here earthquakes near Yolo County
Solano County, CA 55 km (34 mi) WNW of here earthquakes near Solano County
Marin County, CA 55 km (34 mi) NNE of here earthquakes near Marin County
Lake County, CA 70 km (44 mi) SSE of here earthquakes near Lake County

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

Aftershocks so far

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

  1. 2.4 Northern California
  2. 2.6 6 km W of Cobb, California
  3. 2.0 6 km W of Cobb, California
  4. 2.5 4 km WSW of Cobb, California
  5. 1.6 6 km W of Cobb, California
  6. 1.5 4 km SSW of Oakville, California
  7. 1.6 7 km W of Cobb, California
  8. 2.5 14 km NNW of Moskowite Corner, California
  9. 1.8 5 km WSW of Cobb, California
  10. 1.8 7 km W of Cobb, California
  11. 2.9 11 km NE of Angwin, California
  12. 1.6 9 km W of Cobb, California
  13. 2.0 7 km W of Cobb, California
  14. 1.6 8 km W of Cobb, California
  15. 2.8 9 km WNW of Cobb, 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.

For this area

The largest earthquake within 50 km in our catalogue was M 5.0 on 2016-12-14 — it released about 57,000 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.