QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

Earthquake near Big Bear City, CA

No earthquake was likely felt in Big Bear City in the 24 hours to 4:42 am PST (12:42 UTC). The last one was M 1.5, 10 km (6 mi) ESE, at 12:11 pm PST on 3 November 2026, estimated intensity II (weak) in town. Every earthquake near Big Bear City

This page: a magnitude 1.5 earthquake was recorded 7 km (4 mi) south-southeast of Big Bear City, CA, at 11:29 am PDT on 21 September 2018 (18:29 UTC), 2.5 km deep.

USGS: 7km SSE of Big Bear City, CA

29 km (18 mi) NE of Yucaipa, CA · 149 km (93 mi) E of Los Angeles, CA

11:29 am PDT, Sep 21, 2018 · · 2.5 km deep · released about 5.9 lb of TNT

10 km30 km60 km120 km N Riverside County 91 kmSan Bernardino County 92 kmOrange 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
11:29 am PDT on 21 September 2018 ()
Where
7 km (4 mi) south-southeast of Big Bear City, CA · earthquakes near Big Bear City
Magnitude
M 1.5 (ml)
Depth
2.5 km below the surface
Felt
no reports yet
Nearest
Riverside County, 91 km SE
Nearest mapped fault
Helendale-South Lockhart 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 2942 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 10 km (6 mi) from the epicentre. In Big Bear City, 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: Big Bear City 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 5.9 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,800,000× the energy of this one
  3. Around the size people start to feel M 3.0 160× the energy of this one
  4. This earthquake M 1.5 about 5.9 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 4.5 on 2018-05-08 — about 28,000 times the energy of this one.

Before 2016, the USGS record lists 34 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.3 The 1992 Landers, California Earthquake · 34 km E of this epicentre
  2. 6.3 The 1992 Big Bear, California Earthquake · 2 km WSW of this epicentre
  3. 6.2 3 km SE of San Bernardino, California · 43 km WSW of this epicentre
  4. 6.0 The 1986 North Palm Springs, California Earthquake · 30 km SE of this epicentre
  5. 5.8 3km NE of Yucca Valley, California · 38 km ESE 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 34.2062, -116.8090. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Riverside County, CA 91 km (57 mi) SE earthquakes near Riverside County
San Bernardino County, CA 92 km (57 mi) NE earthquakes near San Bernardino County
Orange County, CA 107 km (67 mi) WSW earthquakes near Orange County

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

Aftershocks so far

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

  1. 1.7 39km NE of Big Bear City, CA
  2. 2.0 17km NW of Morongo Valley, CA
  3. 1.6 2km NE of Banning, CA
  4. 2.5 3km SW of Morongo Valley, CA
  5. 2.0 2km ESE of Loma Linda, CA
  6. 2.1 8km NNE of Beaumont, CA
  7. 1.8 19km N of Yucca Valley, CA
  8. 1.6 8km NNE of Beaumont, CA
  9. 1.8 11km NNE of Running Springs, CA
  10. 1.5 8km NNE of Beaumont, CA
  11. 1.9 35km WSW of Ludlow, CA
  12. 2.1 8km NNE of Beaumont, CA
  13. 1.8 14km N of Cabazon, CA
  14. 1.7 14km SSE of Big Bear Lake, CA
  15. 1.8 9km NNW of Banning, 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.