QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

Earthquake near Alpine, CA

No earthquake was likely felt in Alpine in the 24 hours to 12:22 am PST (08:22 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 1.9 earthquake was recorded 34 km (21 mi) east-southeast of Alpine, CA, at 1:59 pm PDT on 6 May 2017 (20:59 UTC), 13 km deep.

USGS: 10 km S of Mt Laguna, California

68 km (42 mi) E of San Diego, CA · 52 km (32 mi) E of El Cajon, CA

1:59 pm PDT, May 6, 2017 · · 13 km deep · released about 20 lb of TNT

10 km30 km60 km120 km N San Diego County 44 kmImperial County 103 kmRiverside County 113 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
1:59 pm PDT on 6 May 2017 ()
Where
34 km (21 mi) east-southeast of Alpine, CA · earthquakes near Alpine
Magnitude
M 1.9 (ml)
Depth
13 km below the surface
Felt
no reports yet
Nearest
San Diego County, 44 km NW
Nearest mapped fault
Elsinore fault, 20 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 3468 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 7 km (4 mi) from the epicentre. In Alpine, 34 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: Pine Valley, Campo, Descanso.

How big was it?

This earthquake released about 20 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 760,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 540,000× the energy of this one
  3. Around the size people start to feel M 3.0 48× the energy of this one
  4. This earthquake M 1.9 about 20 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 3 earthquakes of M5 or more within 50 km:

  1. 5.7 8km ESE of Ocotillo, CA · 47 km E of this epicentre
  2. 5.2 21km NW of Ocotillo, CA · 27 km ENE of this epicentre
  3. 5.0 26km NE of Pine Valley, CA · 23 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 32.7725, -116.4065. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Diego County, CA 44 km (28 mi) NW earthquakes near San Diego County
Imperial County, CA 103 km (64 mi) ENE earthquakes near Imperial County
Riverside County, CA 113 km (70 mi) NNE earthquakes near Riverside County

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

Aftershocks so far

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

  1. 1.6 17km SSW of Ocotillo Wells, CA
  2. 1.6 16km ESE of Julian, CA
  3. 1.6 16km ESE of Julian, CA
  4. 1.8 27km SSW of Ocotillo Wells, CA
  5. 1.8 27km SSW of Ocotillo Wells, CA
  6. 2.6 10km SE of Ocotillo Wells, CA
  7. 2.2 20km NE of Pine Valley, CA
  8. 2.3 10km NE of Julian, CA
  9. 1.6 7km S of Borrego Springs, CA
  10. 1.9 7km S of Borrego Springs, CA
  11. 1.8 14km SSW of Ocotillo Wells, CA
  12. 1.9 14km SSW of Ocotillo Wells, CA
  13. 1.6 9km ESE of San Diego Country Estates, CA
  14. 1.7 9km ESE of San Diego Country Estates, CA
  15. 1.7 16km SSW of Ocotillo Wells, 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.