QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

1km WNW of Little Grass Valley, CA

· 4.0 km deep · released about 15 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Plumas County 33 kmSierra County 43 kmNevada County 51 kmButte County 53 kmYuba County 59 kmPlacer County 77 kmSutter County 98 kmEl Dorado County 111 kmLassen County 115 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
4.0 km below the surface
Felt
no reports yet
Nearest
Plumas County, 33 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2572 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 15 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 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 730,000× the energy of this one
  3. Around the size people start to feel M 3.0 65× the energy of this one
  4. This earthquake M 1.8 about 15 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 39.7210, -120.9903. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Plumas County, CA 33 km (21 mi) SSW of here earthquakes near Plumas County
Sierra County, CA 43 km (27 mi) WNW of here earthquakes near Sierra County
Nevada County, CA 51 km (32 mi) NNW of here earthquakes near Nevada County
Butte County, CA 53 km (33 mi) E of here earthquakes near Butte County
Yuba County, CA 59 km (36 mi) NNE of here earthquakes near Yuba County
Placer County, CA 77 km (48 mi) NNW of here earthquakes near Placer County

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

Aftershocks so far

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

  1. 1.8 3km N of Spring Garden, CA
  2. 2.4 1km NE of Twain, CA
  3. 1.5 4km N of Twain, CA
  4. 1.6 3km NW of Greenville, CA
  5. 1.5 7km NW of Indian Falls, CA
  6. 2.5 5km NNE of East Quincy, CA
  7. 1.9 8km WNW of Caribou, CA
  8. 1.9 5km NE of Greenhorn, CA
  9. 2.5 4km NE of Greenhorn, CA
  10. 1.5 5 km SSW of Sattley, California
  11. 1.8 2km SSW of Canyondam, CA
  12. 1.9 20km SW of Whitehawk, CA
  13. 1.7 7km NNW of Belden, CA
  14. 1.9 3km NNW of Johnsville, CA
  15. 2.4 6km SSE of Challenge-Brownsville, 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.