QuakeIndex

quarry blast · reviewed by a seismologist

M 2.1md

1 km NW of Columbia, California

· -1.0 km deep · released about 44 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Calaveras County 21 kmTuolumne County 39 kmAmador County 49 kmMariposa County 68 kmStanislaus County 75 kmSan Joaquin County 76 kmEl Dorado County 83 kmAlpine County 84 kmSacramento County 93 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 2.1 (md)
Depth
-1.0 km below the surface
Felt
no reports yet
Nearest
Calaveras County, 21 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3398 days ago

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

USGS catalogues this as quarry blast, not an earthquake.

How big was it?

This earthquake released about 44 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 340,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 240,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. This earthquake M 2.1 about 44 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 38.0438, -120.4122. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Calaveras County, CA 21 km (13 mi) SE of here earthquakes near Calaveras County
Tuolumne County, CA 39 km (24 mi) W of here earthquakes near Tuolumne County
Amador County, CA 49 km (31 mi) SSE of here earthquakes near Amador County
Mariposa County, CA 68 km (42 mi) NW of here earthquakes near Mariposa County
Stanislaus County, CA 75 km (46 mi) NE of here earthquakes near Stanislaus County
San Joaquin County, CA 76 km (47 mi) E of here earthquakes near San Joaquin County

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

Aftershocks so far

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

  1. 2.2 9 km NW of Chinese Camp, CA
  2. 2.1 20 km ENE of Mi-Wuk Village, CA
  3. 1.9 18km E of Groveland-Big Oak Flat, CA
  4. 2.3 6km S of Vallecito, CA
  5. 2.1 11km E of Groveland-Big Oak Flat, CA
  6. 1.8 7km WNW of Chinese Camp, CA
  7. 1.5 16km ESE of Groveland-Big Oak Flat, CA
  8. 2.5 18km SE of Groveland-Big Oak Flat, CA
  9. 1.9 3km WNW of Chinese Camp, CA
  10. 2.3 14km S of Groveland-Big Oak Flat, CA
  11. 1.7 4 km SSE of Vallecito, California
  12. 1.5 Northern California
  13. 1.7 3 km ESE of Murphys, California
  14. 1.5 4 km WNW of Tuttletown, California
  15. 1.5 4 km ESE of Vallecito, 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.

On USGS

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