QuakeIndex

quarry blast · reviewed by a seismologist

M 1.8md

6km NNE of Santa Margarita, CA

· -0.3 km deep · released about 14 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Luis Obispo County 12 kmKings County 99 kmSanta Barbara County 111 kmMonterey County 112 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
-0.3 km below the surface
Felt
no reports yet
Nearest
San Luis Obispo County, 12 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2299 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 14 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 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 790,000× the energy of this one
  3. Around the size people start to feel M 3.0 70× the energy of this one
  4. This earthquake M 1.8 about 14 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 35.4323, -120.5755. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
San Luis Obispo County, CA 12 km (8 mi) WNW of here earthquakes near San Luis Obispo County
Kings County, CA 99 km (61 mi) SW of here earthquakes near Kings County
Santa Barbara County, CA 111 km (69 mi) NNW of here earthquakes near Santa Barbara County
Monterey County, CA 112 km (70 mi) SE of here earthquakes near Monterey County

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

Aftershocks so far

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

  1. 1.9 6km SW of San Luis Obispo, CA
  2. 1.7 6km E of Atascadero, CA
  3. 2.7 13km WSW of Parkfield, CA
  4. 1.7 6km E of Atascadero, CA
  5. 2.4 10km W of Templeton, CA
  6. 1.8 10km W of Templeton, CA
  7. 2.7 10km W of Templeton, CA
  8. 1.6 8km WSW of Atascadero, CA
  9. 1.6 9km NNW of Cholame, CA
  10. 1.8 10km NE of Cayucos, CA
  11. 1.7 9km W of Templeton, CA
  12. 1.7 16km SSE of Shandon, CA
  13. 1.7 8km NNE of Cayucos, CA
  14. 1.6 8km NNE of Cayucos, CA
  15. 1.8 6km E of Atascadero, 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 4.3 on 2019-12-17 — it released about 6,000 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.