QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

Earthquake near Rancho Cucamonga, CA

No earthquake was likely felt in Rancho Cucamonga in the 24 hours to 7:50 am PST (15:50 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 1.9 earthquake was recorded 12 km (7 mi) north of Rancho Cucamonga, CA, at 10:39 am PDT on 30 August 2017 (17:39 UTC), 12 km deep.

USGS: 8km SW of Lytle Creek, CA

9 km (6 mi) N of Rancho Cucamonga, CA · 80 km (50 mi) ENE of Los Angeles, CA

10:39 am PDT, Aug 30, 2017 · · 12 km deep · released about 25 lb of TNT

Every earthquake near Rancho Cucamonga Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Orange County 63 kmLos Angeles County 64 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
10:39 am PDT on 30 August 2017 ()
Where
12 km (7 mi) north of Rancho Cucamonga, CA · earthquakes near Rancho Cucamonga
Magnitude
M 1.9 (ml)
Depth
12 km below the surface
Felt
no reports yet
Nearest
Orange County, 63 km SSW
Nearest mapped fault
San Jacinto fault, under 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 3304 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 9 km (6 mi) from the epicentre. In Rancho Cucamonga, 12 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: San Antonio Heights, Upland, Wrightwood, Fontana, Ontario, Montclair.

How big was it?

This earthquake released about 25 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 5.8 620,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 440,000× the energy of this one
  3. Around the size people start to feel M 3.0 39× the energy of this one
  4. This earthquake M 1.9 about 25 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 9 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 3 km SE of San Bernardino, California · 32 km ESE of this epicentre
  2. 5.9 The 1987 Whittier Narrows, California Earthquake · 50 km WSW of this epicentre
  3. 5.8 The 1991 Sierra Madre, California Earthquake · 40 km W of this epicentre
  4. 5.6 7km ENE of Running Springs, CA · 49 km E of this epicentre
  5. 5.5 The 1990 Upland, California Earthquake · 14 km WSW 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 34.2122, -117.5680. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Orange County, CA 63 km (39 mi) SSW earthquakes near Orange County
Los Angeles County, CA 64 km (40 mi) W earthquakes near Los Angeles 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. 2.4 4km SSW of Yorba Linda, CA
  2. 2.1 4km SSW of Yorba Linda, CA
  3. 1.6 4km ESE of Placentia, CA
  4. 1.6 4km SSW of Yorba Linda, CA
  5. 2.4 4km SSW of Yorba Linda, CA
  6. 1.7 14km SW of Lucerne Valley, CA
  7. 1.6 6km SE of Ontario, CA
  8. 1.7 2km SSE of Muscoy, CA
  9. 1.6 2km ESE of Loma Linda, CA
  10. 2.1 2km NNE of Loma Linda, CA
  11. 1.6 5km SSW of Redlands, CA
  12. 2.1 2km SE of Loma Linda, CA
  13. 2.6 3km SE of Loma Linda, CA
  14. 2.6 6km ENE of Lake Arrowhead, CA
  15. 1.9 6km ENE of Lake Arrowhead, 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.