QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

Earthquake near Santa Maria, CA

No earthquake was likely felt in Santa Maria in the 24 hours to 4:32 am PST (12:32 UTC). The last one was M 4.1, 74 km (46 mi) NNW, at 9:54 am PST on 18 November 2025, estimated intensity II (weak) in town; 1,099 felt reports to USGS. Every earthquake near Santa Maria

This page: a magnitude 1.8 earthquake was recorded 11 km (7 mi) east-northeast of Santa Maria, CA, at 7:29 am PST on 6 March 2021 (15:29 UTC), 2.6 km deep. 3 people have reported feeling it to USGS.

USGS: 11km ENE of Santa Maria, CA

13 km (8 mi) ENE of Santa Maria, CA

7:29 am PST, Mar 6, 2021 · · 2.6 km deep · released about 16 lb of TNT

Every earthquake near Santa Maria Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Luis Obispo County 46 kmSanta Barbara County 56 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
7:29 am PST on 6 March 2021 ()
Where
11 km (7 mi) east-northeast of Santa Maria, CA · earthquakes near Santa Maria
Magnitude
M 1.8 (ml)
Depth
2.6 km below the surface
Felt
3 reports · strongest reported intensity II
Nearest
San Luis Obispo County, 46 km NNW
Nearest mapped fault
Los Osos fault, 18 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 1556 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 14 km (9 mi) from the epicentre. In Santa Maria, 11 km away, the estimate is intensity II (weak). 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: Nipomo, Orcutt, Guadalupe, Callender, Los Alamos, Arroyo Grande.

How big was it?

This earthquake released about 16 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 5.8 930,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 660,000× the energy of this one
  3. Around the size people start to feel M 3.0 59× the energy of this one
  4. This earthquake M 1.8 about 16 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

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

  1. 6.9 The 1927 Lompoc, California Earthquake · 49 km SW of this epicentre
  2. 5.8 Near Los Alamos, California · 22 km SSW of this epicentre
  3. 5.8 Near Los Alamos, California · 32 km S of this epicentre
  4. 5.7 Near Los Alamos, California · 44 km SSE of this epicentre
  5. 5.0 5 km SSW of Nipomo, California · 16 km W 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 34.9870, -120.3212. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Luis Obispo County, CA 46 km (29 mi) NNW earthquakes near San Luis Obispo County
Santa Barbara County, CA 56 km (35 mi) SSE earthquakes near Santa Barbara County
Ventura County, CA 129 km (80 mi) ESE earthquakes near Ventura County

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

Aftershocks so far

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

  1. 1.5 8 km ESE of Lompoc, CA
  2. 2.0 17 km W of Vandenberg Air Force Base, CA
  3. 2.5 16 km W of Simmler, CA
  4. 1.5 4 km NW of San Luis Obispo, CA
  5. 1.6 10 km NW of Los Olivos, CA
  6. 1.8 4 km SW of Solvang, CA
  7. 1.6 10 km NW of Los Olivos, CA
  8. 1.5 18 km ESE of Santa Margarita, CA
  9. 1.6 8 km SE of Los Alamos, CA
  10. 1.7 10 km ENE of Los Olivos, CA
  11. 1.5 7 km NW of Los Olivos, CA
  12. 1.9 24 km ESE of Santa Margarita, CA
  13. 1.8 10km W of Orcutt, CA
  14. 2.0 9km NW of Los Alamos, CA
  15. 1.5 9km E of San Luis Obispo, 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.