QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

21km WNW of Simmler, CA

· 6.5 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 23 kmKings County 78 kmSanta Barbara County 102 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
6.5 km below the surface
Felt
no reports yet
Nearest
San Luis Obispo County, 23 km WSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2432 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 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 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 810,000× the energy of this one
  3. Around the size people start to feel M 3.0 72× 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 35.4480, -120.2045. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
San Luis Obispo County, CA 23 km (14 mi) ENE of here earthquakes near San Luis Obispo County
Kings County, CA 78 km (48 mi) SSW of here earthquakes near Kings County
Santa Barbara County, CA 102 km (64 mi) N of here earthquakes near Santa Barbara County
Monterey County, CA 133 km (83 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

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

  1. 1.7 6km E of Atascadero, CA
  2. 1.6 9km NNW of Cholame, CA
  3. 1.7 16km SSE of Shandon, CA
  4. 1.8 6km E of Atascadero, CA
  5. 1.6 22km S of Kettleman City, CA
  6. 2.4 24km SE of Santa Margarita, CA
  7. 1.9 6km NE of San Luis Obispo, CA
  8. 1.8 6km W of Santa Margarita, CA
  9. 1.6 21km SE of Shandon, CA
  10. 3.0 5km S of Shandon, CA
  11. 2.0 23km NNE of Nipomo, CA
  12. 1.7 10km SSE of Parkfield, CA
  13. 1.9 10km SSE of Parkfield, CA
  14. 1.6 4km SW of Paso Robles, CA
  15. 1.7 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 6,200 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.