Earthquake · reviewed by a seismologist
M 4.0mw
Earthquake near Ontario, CA
No earthquake was likely felt in Ontario in the 24 hours to 12:10 pm PST (20:10 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 4.0 earthquake was recorded 7 km (4 mi) southeast of Ontario, CA, at 10:34 am PDT on 7 September 2024 (17:34 UTC), 4.8 km deep. 2,758 people have reported feeling it to USGS.
USGS: 4 km SE of Ontario, CA
in Ontario, CA · 76 km (47 mi) E of Los Angeles, CA
- When
- 10:34 am PDT on 7 September 2024 ()
- Where
- 7 km (4 mi) southeast of Ontario, CA · earthquakes near Ontario
- Magnitude
- M 4.0 (mw)
- Depth
- 4.8 km below the surface
- Felt
- 2,758 reports · strongest reported intensity V
- Measured shaking
- intensity V (ShakeMap)
- Tsunami
- USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
- Nearest
- Orange County, 43 km SSW
- Nearest mapped fault
- Red Hill-Etiwanda Avenue fault, 10 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 577 days ago
Earthquake alerts for Ontario, CA
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Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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 93 km (58 mi) from the epicentre. In Ontario, 7 km away, the estimate is intensity IV (light). 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: Ontario 7 km, intensity IV · Eastvale 7 km, intensity IV · Rancho Cucamonga 9 km, intensity IV · Chino 9 km, intensity IV · Upland 10 km, intensity IV · Montclair 11 km, intensity IV · Norco 11 km, intensity IV · Pedley 12 km, intensity IV. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 13 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 13,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 600× the energy of this one
- Magna, Utah 2020 M 5.7 420× the energy of this one
- This earthquake M 4.0 about 13 tons of TNT
- Around the size people start to feel M 3.0 this one released 27× more
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 7.7 times the energy of this one.
Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:
- 6.2 3 km SE of San Bernardino, California · 31 km ENE of this epicentre
- 6.0 The 1910 Lake Elsinore, California Earthquake · 40 km SSE of this epicentre
- 5.9 The 1987 Whittier Narrows, California Earthquake · 45 km W of this epicentre
- 5.8 The 1991 Sierra Madre, California Earthquake · 46 km NW of this epicentre
- 5.5 The 1990 Upland, California Earthquake · 16 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 34.0260, -117.5908. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Orange County, CA | 43 km (26 mi) | SSW | earthquakes near Orange County |
| Los Angeles County, CA | 65 km (40 mi) | WNW | earthquakes near Los Angeles County |
| San Diego County, CA | 135 km (84 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
56 earthquakes have been recorded within 50 km since this one.
- 1.5 3 km S of Fontana, CA
- 1.8 2 km SSE of Fontana, CA
- 1.7 2 km S of Fontana, CA
- 1.7 2 km NNE of Villa Park, CA
- 1.6 6 km NNE of Fontana, CA
- 1.6 9 km WSW of Lytle Creek, CA
- 1.6 3 km SE of Ontario, CA
- 3.5 2 km SE of Ontario, CA
- 1.7 4 km SE of Ontario, CA
- 1.8 6 km SW of Corona, CA
- 3.1 7 km NW of Glen Avon, CA
- 1.9 8 km SSE of Home Gardens, CA
- 1.5 2 km SSE of Fontana, CA
- 2.3 3 km S of Fontana, CA
- 1.7 3 km S 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
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.