QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near San Luis Obispo, CA

No earthquake was likely felt in San Luis Obispo in the 24 hours to 3:47 pm PST (23:47 UTC). The last one was M 2.5, 18 km (11 mi) NNW, at 11:41 pm PDT on 15 August 2026, estimated intensity II (weak) in town; 61 felt reports to USGS. Every earthquake near San Luis Obispo

This page: a magnitude 1.8 earthquake was recorded 45 km (28 mi) east-northeast of San Luis Obispo, CA, at 12:53 pm PST on 20 January 2020 (20:53 UTC), 6.5 km deep.

USGS: 21km WNW of Simmler, CA

12:53 pm PST, Jan 20, 2020 · · 6.5 km deep · released about 13 lb of TNT

Every earthquake near San Luis Obispo 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
12:53 pm PST on 20 January 2020 ()
Where
45 km (28 mi) east-northeast of San Luis Obispo, CA · earthquakes near San Luis Obispo
Magnitude
M 1.8 (md)
Depth
6.5 km below the surface
Felt
no reports yet
Nearest
San Luis Obispo County, 23 km WSW
Nearest mapped fault
San Juan fault, 2 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2479 days ago

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

At this magnitude and depth, people at rest would likely notice it out to about 11 km (7 mi) from the epicentre. In San Luis Obispo, 45 km away, the estimate is intensity I (not felt). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

Earthquakes near other towns within 30 km: Shandon.

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.

For this area

The largest earthquake within 50 km since 2016 was M 4.3 on 2019-12-17 — about 6,200 times the energy of this one.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

  1. 6.5 1922 Parkfield, California Earthquake · 34 km N of this epicentre
  2. 6.0 2004 Parkfield, California Earthquake · 44 km NNW of this epicentre
  3. 5.5 1966 Parkfield, California Earthquake · 39 km NNW of this epicentre
  4. 5.0 11 km NNE of Shandon, California · 35 km NNW of this epicentre
  5. 5.0 11 km NNE of Shandon, California · 35 km NNW of this epicentre

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Epicentre 35.4480, -120.2045. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Luis Obispo County, CA 23 km (14 mi) WSW earthquakes near San Luis Obispo County
Kings County, CA 78 km (48 mi) NNE earthquakes near Kings County
Santa Barbara County, CA 102 km (64 mi) S earthquakes near Santa Barbara County
Monterey County, CA 133 km (83 mi) NW 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.

On USGS

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