QuakeIndex

Earthquake · reviewed by a seismologist

M 2.5ml

Earthquake near Lompoc, CA

No earthquake was likely felt in Lompoc in the 24 hours to 5:54 pm PST (01:54 UTC). The last one was M 2.3, 11 km (7 mi) SSW, at 6:34 am PDT on 26 August 2026, estimated intensity II (weak) in town. Every earthquake near Lompoc

This page: a magnitude 2.5 earthquake was recorded 23 km (14 mi) west of Lompoc, CA, at 10:04 pm PDT on 23 September 2017 (05:04 UTC), less than 1 km deep. 15 people have reported feeling it to USGS.

USGS: 23km SW of Vandenberg Air Force Base, CA

43 km (27 mi) SW of Santa Maria, CA

10:04 pm PDT, Sep 23, 2017 · · -0.3 km deep · released about 190 lb of TNT

Every earthquake near Lompoc Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Barbara County 62 kmSan Luis Obispo County 90 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
10:04 pm PDT on 23 September 2017 ()
Where
23 km (14 mi) west of Lompoc, CA · earthquakes near Lompoc
Magnitude
M 2.5 (ml)
Depth
-0.3 km below the surface
Felt
15 reports · strongest reported intensity III
Nearest
Santa Barbara County, 62 km E
Nearest mapped fault
Hosgri fault, 3 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 3305 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 23 km (14 mi) from the epicentre. In Lompoc, 23 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: Vandenberg Space Force Base, Vandenberg Village, Mission Hills.

How big was it?

This earthquake released about 190 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 78,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 55,000× the energy of this one
  3. Around the size people start to feel M 3.0 4.9× the energy of this one
  4. This earthquake M 2.5 about 190 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 · 8 km N of this epicentre
  2. 5.8 Near Los Alamos, California · 35 km NE of this epicentre
  3. 5.8 Near Los Alamos, California · 39 km ENE of this epicentre
  4. 5.7 Near Los Alamos, California · 47 km E of this epicentre
  5. 5.0 5 km SSW of Nipomo, California · 47 km NNE 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 34.6112, -120.7088. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Barbara County, CA 62 km (38 mi) E earthquakes near Santa Barbara County
San Luis Obispo County, CA 90 km (56 mi) NNE earthquakes near San Luis Obispo County

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

Aftershocks so far

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

  1. 2.6 12km SSW of Lompoc, CA
  2. 2.1 13km SSW of Lompoc, CA
  3. 2.0 13km SSW of Lompoc, CA
  4. 2.0 31 km SW of Lompoc, CA
  5. 2.6 13km SSW of Lompoc, CA
  6. 2.1 5km SSW of Orcutt, CA
  7. 2.6 52km WSW of Lompoc, CA
  8. 2.1 42km SW of Lompoc, CA
  9. 2.1 12km E of Orcutt, CA
  10. 2.5 11km E of Orcutt, CA
  11. 2.1 11km E of Orcutt, CA
  12. 1.6 8km E of Vandenberg Village, CA
  13. 2.1 12km NNW of Vandenberg Air Force Base, CA
  14. 1.9 24km SW of Lompoc, CA
  15. 2.1 27km SW of Lompoc, 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.