QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

Earthquake near Lompoc, CA

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

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

6:26 am PST, Dec 31, 2017 · · -0.3 km deep · released about 51 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 89 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
6:26 am PST on 31 December 2017 ()
Where
23 km (15 mi) W of Lompoc, CA · earthquakes near Lompoc
Magnitude
M 2.1 (ml)
Depth
-0.3 km below the surface
Felt
2 reports · strongest reported intensity III
Nearest
Santa Barbara County, 62 km E
Nearest mapped fault
Hosgri 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 3194 days ago

A magnitude 2.1 earthquake was recorded 23 km (15 mi) W of Lompoc, CA, at 6:26 am PST on 31 December 2017 (14:26 UTC). 2 people have reported feeling it to USGS. This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

Earthquakes near other towns within 30 km: Vandenberg Space Force Base, Vandenberg Village, Mission Hills.

How big was it?

This earthquake released about 51 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 300,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 210,000× the energy of this one
  3. Around the size people start to feel M 3.0 19× the energy of this one
  4. This earthquake M 2.1 about 51 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 2017-10-26 — about 1,900 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 · 7 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 34.6177, -120.7128. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Barbara County, CA 62 km (39 mi) E earthquakes near Santa Barbara County
San Luis Obispo County, CA 89 km (55 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

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

  1. 2.2 36km WSW of Guadalupe, CA
  2. 2.1 32km WSW of Guadalupe, CA
  3. 2.5 22km SW of Lompoc, CA
  4. 1.6 10km NNE of Los Alamos, CA
  5. 2.5 40km SW of Avila Beach, CA
  6. 2.6 18km SSW of Lompoc, CA
  7. 2.1 21km SSW of Lompoc, CA
  8. 2.7 6km NNE of Los Alamos, CA
  9. 1.8 9km NE of Los Alamos, CA
  10. 2.4 4km NE of Orcutt, CA
  11. 1.8 19km SSW of Lompoc, CA
  12. 2.6 20km SSW of Lompoc, CA
  13. 1.7 19km SSW of Lompoc, CA
  14. 2.6 12km SSW of Lompoc, CA
  15. 2.1 13km SSW 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.