Earthquake · reviewed by a seismologist
M 1.6ml
Earthquake near Muscoy, CA
No earthquake was likely felt in Muscoy in the 24 hours to 11:47 am PST (19:47 UTC). The last one was M 2.2, 17 km (10 mi) SE, at 8:15 pm PDT on 29 October 2026, estimated intensity II (weak) in town; 1 felt report to USGS. Every earthquake near Muscoy
This page: a magnitude 1.6 earthquake was recorded in Muscoy, CA, at 7:15 pm PDT on 21 October 2023 (02:15 UTC), 5.5 km deep.
USGS: 1 km SSW of Muscoy, CA
in San Bernardino, CA
- When
- 7:15 pm PDT on 21 October 2023 ()
- Where
- in Muscoy, CA · earthquakes near Muscoy
- Magnitude
- M 1.6 (ml)
- Depth
- 5.5 km below the surface
- Felt
- no reports yet
- Nearest
- Orange County, 66 km SW
- 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 1117 days ago
Earthquake alerts for Muscoy, 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 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. 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: Muscoy in town, intensity II · Rialto 5 km, intensity II · San Bernardino 7 km, intensity II · Colton 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 6.6 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,300,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,600,000× the energy of this one
- Around the size people start to feel M 3.0 140× the energy of this one
- This earthquake M 1.6 about 6.6 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 2016-01-06 — about 18,000 times the energy of this one.
Before 2016, the USGS record lists 18 earthquakes of M5 or more within 50 km; the five largest:
- 6.3 The 1992 Big Bear, California Earthquake · 48 km E of this epicentre
- 6.2 3 km SE of San Bernardino, California · 10 km SE of this epicentre
- 6.0 The 1910 Lake Elsinore, California Earthquake · 50 km S of this epicentre
- 5.6 7km ENE of Running Springs, CA · 30 km ENE of this epicentre
- 5.5 The 1990 Upland, California Earthquake · 32 km W 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 34.1465, -117.3475. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Orange County, CA | 66 km (41 mi) | SW | earthquakes near Orange County |
| Los Angeles County, CA | 84 km (52 mi) | W | earthquakes near Los Angeles County |
| San Bernardino County, CA | 133 km (83 mi) | NE | earthquakes near San Bernardino County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
44 earthquakes have been recorded within 50 km since this one.
- 2.2 3 km WSW of Redlands, CA
- 2.6 7 km E of Calimesa, CA
- 1.9 2 km ESE of Colton, CA
- 1.6 12 km SSW of Big Bear Lake, CA
- 1.9 4 km SE of Lytle Creek, CA
- 2.3 5 km ESE of Lytle Creek, CA
- 2.0 3 km NE of Colton, CA
- 1.6 6 km NE of Moreno Valley, CA
- 2.7 5 km NNE of Fontana, CA
- 1.6 10 km NNW of Banning, CA
- 2.0 4 km SE of Home Gardens, CA
- 2.7 12 km WNW of Big Bear Lake, CA
- 1.5 5 km ESE of Yucaipa, CA
- 1.5 7 km SSE of Home Gardens, CA
- 1.5 10 km NE of Running Springs, 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.