QuakeIndex

Earthquake · reviewed by a seismologist

M 2.0ml

Earthquake near Rancho Cucamonga, CA

No earthquake was likely felt in Rancho Cucamonga in the 24 hours to 4:28 am PST (12:28 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 2.0 earthquake was recorded 13 km (8 mi) north of Rancho Cucamonga, CA, at 7:48 pm PDT on 21 July 2021 (02:48 UTC), 6.4 km deep. 1 person has reported feeling it to USGS.

USGS: 9km WSW of Lytle Creek, CA

10 km (6 mi) N of Rancho Cucamonga, CA · 80 km (49 mi) ENE of Los Angeles, CA

7:48 pm PDT, Jul 21, 2021 · · 6.4 km deep · released about 28 lb of TNT

Every earthquake near Rancho Cucamonga Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Los Angeles County 63 kmOrange County 63 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
7:48 pm PDT on 21 July 2021 ()
Where
13 km (8 mi) north of Rancho Cucamonga, CA · earthquakes near Rancho Cucamonga
Magnitude
M 2.0 (ml)
Depth
6.4 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Los Angeles County, 63 km W
Nearest mapped fault
San Jacinto fault, 1 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 1939 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 14 km (9 mi) from the epicentre. In Rancho Cucamonga, 13 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: Rancho Cucamonga 13 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 28 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.0 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 540,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 380,000× the energy of this one
  3. Around the size people start to feel M 3.0 34× the energy of this one
  4. This earthquake M 2.0 about 28 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 4.4 on 2018-08-29 — about 4,000 times the energy of this one.

Before 2016, the USGS record lists 9 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 3 km SE of San Bernardino, California · 33 km ESE of this epicentre
  2. 5.9 The 1987 Whittier Narrows, California Earthquake · 49 km WSW of this epicentre
  3. 5.8 The 1991 Sierra Madre, California Earthquake · 38 km W of this epicentre
  4. 5.6 7km ENE of Running Springs, CA · 50 km E of this epicentre
  5. 5.5 The 1990 Upland, California Earthquake · 14 km SW 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 34.2220, -117.5817. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Los Angeles County, CA 63 km (39 mi) W earthquakes near Los Angeles County
Orange County, CA 63 km (39 mi) SSW earthquakes near Orange 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. 2.0 3km SE of Loma Linda, CA
  2. 1.5 5km SE of Home Gardens, CA
  3. 1.6 5km NNE of Fontana, CA
  4. 2.1 3km SW of San Bernardino, CA
  5. 1.9 5km WSW of Devore, CA
  6. 1.6 3km E of Loma Linda, CA
  7. 2.0 4km SE of Home Gardens, CA
  8. 1.9 3km WNW of Fontana, CA
  9. 2.2 5km N of Moreno Valley, CA
  10. 2.4 7km S of Redlands, CA
  11. 1.5 4km NW of Fontana, CA
  12. 1.8 4km SSE of Home Gardens, CA
  13. 1.8 5km SSE of Home Gardens, CA
  14. 1.9 3km NNW of Rancho Cucamonga, CA
  15. 1.8 8km ENE of Moreno Valley, 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.