Earthquake · reviewed by a seismologist
M 2.3ml
Earthquake near Charter Oak, CA
No earthquake was likely felt in Charter Oak in the 24 hours to 2:39 am PST (10:39 UTC). The last one was M 3.6, 64 km (40 mi) WSW, at 8:40 am PDT on 27 September 2026, estimated intensity II (weak) in town; 1,735 felt reports to USGS. Every earthquake near Charter Oak
This page: a magnitude 2.3 earthquake was recorded 3 km (2 mi) south-southeast of Charter Oak, CA, at 7:11 am PDT on 15 August 2018 (14:11 UTC), 14 km deep. 1 person has reported feeling it to USGS.
USGS: 3km SSE of Charter Oak, CA
7 km (4 mi) WNW of Pomona, CA · 53 km (33 mi) E of Los Angeles, CA
- When
- 7:11 am PDT on 15 August 2018 ()
- Where
- 3 km (2 mi) south-southeast of Charter Oak, CA · earthquakes near Charter Oak
- Magnitude
- M 2.3 (ml)
- Depth
- 14 km below the surface
- Felt
- 1 report · strongest reported intensity II
- Nearest
- Los Angeles County, 41 km WNW
- Nearest mapped fault
- Sierra Madre fault, 6 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 3011 days ago
Earthquake alerts for Charter Oak, CA
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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 Charter Oak, 3 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: San Dimas 4 km, intensity II · Covina 5 km, intensity II · Diamond Bar 6 km, intensity II · La Verne 7 km, intensity II · Walnut 7 km, intensity II · Glendora 7 km, intensity II · Pomona 8 km, intensity II · Azusa 9 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 91 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 170,000× the energy of this one
- Magna, Utah 2020 M 5.7 120,000× the energy of this one
- Around the size people start to feel M 3.0 10× the energy of this one
- This earthquake M 2.3 about 91 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 10 earthquakes of M5 or more within 50 km; the five largest:
- 5.9 The 1987 Whittier Narrows, California Earthquake · 22 km W of this epicentre
- 5.8 The 1991 Sierra Madre, California Earthquake · 26 km NW of this epicentre
- 5.5 The 1990 Upland, California Earthquake · 15 km ENE of this epicentre
- 5.4 5km S of Chino Hills, CA · 16 km SSE of this epicentre
- 5.2 3km W of Lytle Creek, CA · 34 km NE 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 34.0778, -117.8360. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Los Angeles County, CA | 41 km (26 mi) | WNW | earthquakes near Los Angeles County |
| Orange County, CA | 45 km (28 mi) | S | earthquakes near Orange County |
| Ventura County, CA | 123 km (77 mi) | WNW | earthquakes near Ventura County |
| San Diego County, CA | 153 km (95 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
49 earthquakes have been recorded within 50 km since this one.
- 2.1 4km ENE of Lytle Creek, CA
- 2.9 4km N of La Verne, CA
- 1.6 1km ESE of Maywood, CA
- 1.7 1km SSW of Gardena, CA
- 1.7 8km SSE of Home Gardens, CA
- 1.6 5km SE of Home Gardens, CA
- 1.5 7km SSE of Home Gardens, CA
- 3.0 9km WSW of Wrightwood, CA
- 1.6 12km SSE of Corona, CA
- 1.9 4km N of La Verne, CA
- 2.1 9km ENE of North Tustin, CA
- 1.8 8km E of Yorba Linda, CA
- 1.9 2km WNW of Orange, CA
- 1.7 3km W of Orange, CA
- 1.7 4km SSE of Devore, 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.