QuakeIndex

Earthquake · reviewed by a seismologist

M 2.9ml

Earthquake near Rancho Cucamonga, CA

No earthquake was likely felt in Rancho Cucamonga in the 24 hours to 3:43 am PST (11:43 UTC). The last one was M 2.0, 10 km (6 mi) E, at 2:35 am PDT on 23 October 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Rancho Cucamonga

This page: a magnitude 2.9 earthquake was recorded 4 km (3 mi) southeast of Rancho Cucamonga, CA, at 2:12 pm PDT on 25 June 2021 (21:12 UTC), 11 km deep. 339 people have reported feeling it to USGS.

USGS: 5km SSE of Rancho Cucamonga, CA

5 km (3 mi) S of Rancho Cucamonga, CA · 79 km (49 mi) E of Los Angeles, CA

2:12 pm PDT, Jun 25, 2021 · · 11 km deep · released about 720 lb of TNT

Every earthquake near Rancho Cucamonga Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Orange County 49 kmLos Angeles County 66 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
2:12 pm PDT on 25 June 2021 ()
Where
4 km (3 mi) southeast of Rancho Cucamonga, CA · earthquakes near Rancho Cucamonga
Magnitude
M 2.9 (ml)
Depth
11 km below the surface
Felt
339 reports · strongest reported intensity III
Measured shaking
intensity III (ShakeMap)
Nearest
Orange County, 49 km SSW
Nearest mapped fault
Red Hill-Etiwanda Avenue fault, 5 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 1696 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 31 km (19 mi) from the epicentre. In Rancho Cucamonga, 4 km away, the estimate is intensity III (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: Rancho Cucamonga 4 km, intensity III · Upland 8 km, intensity III · Ontario 9 km, intensity III · Fontana 11 km, intensity III · Montclair 12 km, intensity III · Eastvale 13 km, intensity II · Pedley 14 km, intensity II · Chino 14 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 720 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 21,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 15,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.3× the energy of this one
  4. This earthquake M 2.9 about 720 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 2020-09-19 — about 270 times the energy of this one.

Before 2016, the USGS record lists 13 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 3 km SE of San Bernardino, California · 28 km E of this epicentre
  2. 6.0 The 1910 Lake Elsinore, California Earthquake · 45 km SSE of this epicentre
  3. 5.9 The 1987 Whittier Narrows, California Earthquake · 48 km W of this epicentre
  4. 5.8 The 1991 Sierra Madre, California Earthquake · 45 km WNW of this epicentre
  5. 5.5 The 1990 Upland, California Earthquake · 15 km WNW 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 34.0815, -117.5587. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Orange County, CA 49 km (31 mi) SSW earthquakes near Orange County
Los Angeles County, CA 66 km (41 mi) WNW earthquakes near Los Angeles County
San Diego County, CA 138 km (86 mi) SSE earthquakes near San Diego County

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

Aftershocks so far

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

  1. 1.6 5km NNE of Fontana, CA
  2. 2.6 5km NNE of Fontana, CA
  3. 2.6 5km SE of Loma Linda, CA
  4. 1.6 4km NE of Whittier, CA
  5. 1.6 4km SW of Highland, CA
  6. 1.9 4km SE of Home Gardens, CA
  7. 2.0 3km E of Loma Linda, CA
  8. 1.7 4km SE of Home Gardens, CA
  9. 1.7 2km ESE of Loma Linda, CA
  10. 1.7 4km N of Fontana, CA
  11. 1.6 4km N of Fontana, CA
  12. 1.8 3km SSE of Devore, CA
  13. 1.6 4km N of Rancho Cucamonga, CA
  14. 1.7 6km SSE of Home Gardens, CA
  15. 1.5 5km NNE of Fontana, 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.