QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6ml

Earthquake near Los Alamos, CA

No earthquake was likely felt in Los Alamos in the 24 hours to 1:34 pm PST (21:34 UTC). The last one was M 2.2, 7 km (4 mi) ENE, at 8:51 am PDT on 23 July 2026, estimated intensity II (weak) in town. Every earthquake near Los Alamos

This page: a magnitude 1.6 earthquake was recorded 7 km (5 mi) southeast of Los Alamos, CA, at 6:27 pm PDT on 29 September 2017 (01:27 UTC), 2.3 km deep.

USGS: 7km SE of Los Alamos, CA

33 km (21 mi) SE of Santa Maria, CA

6:27 pm PDT, Sep 29, 2017 · · 2.3 km deep · released about 7.3 lb of TNT

Every earthquake near Los Alamos Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Barbara County 25 kmSan Luis Obispo County 80 kmVentura County 107 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
6:27 pm PDT on 29 September 2017 ()
Where
7 km (5 mi) southeast of Los Alamos, CA · earthquakes near Los Alamos
Magnitude
M 1.6 (ml)
Depth
2.3 km below the surface
Felt
no reports yet
Nearest
Santa Barbara County, 25 km SE
Nearest mapped fault
Los Alamos fault, 5 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 3304 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 Los Alamos, 7 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.

Likely felt in: Los Alamos 7 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 7.3 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,500,000× the energy of this one
  3. Around the size people start to feel M 3.0 130× the energy of this one
  4. This earthquake M 1.6 about 7.3 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 4.1 on 2017-05-17 — about 5,100 times the energy of this one.

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

  1. 6.9 The 1927 Lompoc, California Earthquake · 43 km W of this epicentre
  2. 5.8 Near Los Alamos, California · 20 km NW of this epicentre
  3. 5.8 Near Los Alamos, California · 6 km W of this epicentre
  4. 5.7 Near Los Alamos, California · 10 km SSE of this epicentre
  5. 5.0 5 km SSW of Nipomo, California · 42 km NW 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 34.6900, -120.2313. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Barbara County, CA 25 km (15 mi) SE earthquakes near Santa Barbara County
San Luis Obispo County, CA 80 km (50 mi) NNW earthquakes near San Luis Obispo County
Ventura County, CA 107 km (67 mi) ESE earthquakes near Ventura County

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

Aftershocks so far

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

  1. 1.9 24km SW of Lompoc, CA
  2. 2.1 27km SW of Lompoc, CA
  3. 1.8 8km E of Vandenberg Village, CA
  4. 1.8 25km SW of Lompoc, CA
  5. 1.7 7km NW of Los Olivos, CA
  6. 1.8 5km SE of Santa Ynez, CA
  7. 1.8 6km SE of Santa Ynez, CA
  8. 2.2 4km ESE of Orcutt, CA
  9. 1.9 17km W of Vandenberg Air Force Base, CA
  10. 2.4 4km ESE of Orcutt, CA
  11. 3.2 4km ESE of Orcutt, CA
  12. 1.5 4km ESE of Orcutt, CA
  13. 1.7 12km NE of Goleta, CA
  14. 2.1 30km S of Solvang, CA
  15. 2.2 12km S of Guadalupe, 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.