QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

Earthquake near Alpine, CA

No earthquake was likely felt in Alpine in the 24 hours to 2:28 am PST (10:28 UTC). The last one was M 4.9, 155 km (96 mi) ESE, at 10:27 am PST on 3 November 2026, estimated intensity II (weak) in town; 321 felt reports to USGS. Every earthquake near Alpine

This page: a magnitude 1.8 earthquake was recorded 48 km (30 mi) east-northeast of Alpine, CA, at 10:22 am PST on 21 November 2018 (18:22 UTC), 6.8 km deep.

USGS: 26km SSW of Ocotillo Wells, CA

82 km (51 mi) E of San Diego, CA

10:22 am PST, Nov 21, 2018 · · 6.8 km deep · released about 14 lb of TNT

Every earthquake near Alpine Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Diego County 49 kmImperial County 86 kmRiverside County 92 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
10:22 am PST on 21 November 2018 ()
Where
48 km (30 mi) east-northeast of Alpine, CA · earthquakes near Alpine
Magnitude
M 1.8 (ml)
Depth
6.8 km below the surface
Felt
no reports yet
Nearest
San Diego County, 49 km WNW
Nearest mapped fault
Elsinore fault, 9 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 2913 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 Alpine, 48 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: Pine Valley.

How big was it?

This earthquake released about 14 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 5.7 790,000× the energy of this one
  3. Around the size people start to feel M 3.0 70× the energy of this one
  4. This earthquake M 1.8 about 14 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 4.0 on 2016-07-31 — about 2,500 times the energy of this one.

Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 The 1942 Fish Creek Mountains, California Earthquake · 45 km E of this epicentre
  2. 6.6 The 1968 Borrego Mountain, California Earthquake · 31 km NNE of this epicentre
  3. 6.6 The 1987 Superstition Hills, California Earthquake · 40 km ENE of this epicentre
  4. 6.4 The 1954 San Jacinto Fault, California Earthquake · 44 km NNE of this epicentre
  5. 6.2 The 1987 Elmore Ranch, California Earthquake · 47 km ENE 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 32.9345, -116.2660. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Diego County, CA 49 km (30 mi) WNW earthquakes near San Diego County
Imperial County, CA 86 km (53 mi) E earthquakes near Imperial County
Riverside County, CA 92 km (57 mi) NNE earthquakes near Riverside County

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

Aftershocks so far

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

  1. 1.5 8km ENE of Julian, CA
  2. 2.1 8km NNW of Borrego Springs, CA
  3. 1.8 6km WNW of Borrego Springs, CA
  4. 1.9 15km ESE of Julian, CA
  5. 2.5 8km NNW of Borrego Springs, CA
  6. 1.9 8km NNW of Borrego Springs, CA
  7. 1.9 8km NNW of Borrego Springs, CA
  8. 3.0 7km ESE of Ocotillo Wells, CA
  9. 1.7 24km W of Westmorland, CA
  10. 1.7 16km ESE of Julian, CA
  11. 1.8 8km ENE of Julian, CA
  12. 1.7 4km WNW of Borrego Springs, CA
  13. 1.8 18km SSW of Oasis, CA
  14. 2.0 8km NNW of Borrego Springs, CA
  15. 1.5 8km NNW of Borrego Springs, 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.