QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

Earthquake near Ontario, CA

No earthquake was likely felt in Ontario in the 24 hours to 6:20 am PST (14:20 UTC). The last one was M 1.7, 8 km (5 mi) SE, at 2:48 pm PDT on 9 October 2026, estimated intensity II (weak) in town. Every earthquake near Ontario

This page: a magnitude 2.1 earthquake was recorded 9 km (5 mi) southeast of Ontario, CA, at 2:30 pm PDT on 11 July 2018 (21:30 UTC), 3.8 km deep. 9 people have reported feeling it to USGS.

USGS: 6km SE of Ontario, CA

in Ontario, CA · 76 km (47 mi) E of Los Angeles, CA

2:30 pm PDT, Jul 11, 2018 · · 3.8 km deep · released about 43 lb of TNT

Every earthquake near Ontario Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Orange County 41 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
2:30 pm PDT on 11 July 2018 ()
Where
9 km (5 mi) southeast of Ontario, CA · earthquakes near Ontario
Magnitude
M 2.1 (ml)
Depth
3.8 km below the surface
Felt
9 reports · strongest reported intensity IV
Nearest
Orange County, 41 km SSW
Nearest mapped fault
Red Hill-Etiwanda Avenue fault, 12 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 3030 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 17 km (11 mi) from the epicentre. In Ontario, 9 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: Eastvale 5 km, intensity II · Ontario 9 km, intensity II · Norco 9 km, intensity II · Chino 10 km, intensity II · Pedley 11 km, intensity II · Rancho Cucamonga 11 km, intensity II · Upland 12 km, intensity II · Montclair 12 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. This earthquake M 2.1 about 43 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 14 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 3 km SE of San Bernardino, California · 31 km ENE of this epicentre
  2. 6.0 The 1910 Lake Elsinore, California Earthquake · 38 km SSE of this epicentre
  3. 5.9 The 1987 Whittier Narrows, California Earthquake · 46 km W of this epicentre
  4. 5.8 The 1991 Sierra Madre, California Earthquake · 48 km NW of this epicentre
  5. 5.5 The 1990 Upland, California Earthquake · 18 km NW 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 34.0078, -117.5843. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Orange County, CA 41 km (25 mi) SSW earthquakes near Orange County
Los Angeles County, CA 66 km (41 mi) WNW earthquakes near Los Angeles County
San Diego County, CA 133 km (82 mi) SE earthquakes near San Diego County

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

Aftershocks so far

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

  1. 1.9 5km SE of Home Gardens, CA
  2. 1.9 9km ENE of Villa Park, CA
  3. 1.8 3km E of Loma Linda, CA
  4. 1.6 4km SE of Home Gardens, CA
  5. 2.4 3km NNW of La Verne, CA
  6. 2.1 4km N of La Verne, CA
  7. 1.5 2km SE of Home Gardens, CA
  8. 1.8 4km N of La Verne, CA
  9. 1.9 8km NE of Moreno Valley, CA
  10. 1.5 3km NNW of La Verne, CA
  11. 1.8 5km N of Fontana, CA
  12. 1.5 3km NNW of La Verne, CA
  13. 1.9 0km NE of Loma Linda, CA
  14. 2.0 4km N of La Verne, CA
  15. 1.8 3km NNW of La Verne, 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.