QuakeIndex

quarry blast · reviewed by a seismologist

M 1.8md

6 km E of Atascadero, California

· -0.4 km deep · released about 13 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Luis Obispo County 17 kmKings County 97 kmMonterey County 106 kmSanta Barbara County 117 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
-0.4 km below the surface
Felt
no reports yet
Nearest
San Luis Obispo County, 17 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3447 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 13 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 1,200,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 840,000× the energy of this one
  3. Around the size people start to feel M 3.0 75× the energy of this one
  4. This earthquake M 1.8 about 13 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 35.4810, -120.6025. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
San Luis Obispo County, CA 17 km (11 mi) NW of here earthquakes near San Luis Obispo County
Kings County, CA 97 km (60 mi) SW of here earthquakes near Kings County
Monterey County, CA 106 km (66 mi) SE of here earthquakes near Monterey County
Santa Barbara County, CA 117 km (73 mi) NNW of here earthquakes near Santa Barbara County

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

Aftershocks so far

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

  1. 2.2 4km NNE of Pismo Beach, CA
  2. 2.2 15km W of Lake Nacimiento, CA
  3. 2.4 2 km NW of Parkfield, California
  4. 2.7 2 km WNW of Parkfield, California
  5. 1.6 6 km E of Atascadero, California
  6. 2.5 9 km SW of Oak Shores, California
  7. 1.7 8 km SW of Oak Shores, California
  8. 1.6 6 km SE of Parkfield, California
  9. 1.8 7 km E of Atascadero, California
  10. 2.6 9 km SW of Oak Shores, California
  11. 1.9 11 km NNE of Cambria, California
  12. 1.6 11 km NNE of Cayucos, California
  13. 2.7 8 km SW of Oak Shores, California
  14. 1.6 6 km E of Atascadero, California
  15. 1.9 10 km S of Oak Shores, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.