Earthquake · reviewed by a seismologist
M 1.7ml
Earthquake near Muscoy, CA
No earthquake was likely felt in Muscoy in the 24 hours to 10:19 am PST (18:19 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 1.7 earthquake was recorded 2 km (1 mi) west-northwest of Muscoy, CA, at 8:21 pm PDT on 8 April 2020 (03:21 UTC), 13 km deep.
USGS: 2km WNW of Muscoy, CA
5 km (3 mi) NNE of Rialto, CA · 97 km (61 mi) E of Los Angeles, CA
- When
- 8:21 pm PDT on 8 April 2020 ()
- Where
- 2 km (1 mi) west-northwest of Muscoy, CA · earthquakes near Muscoy
- Magnitude
- M 1.7 (ml)
- Depth
- 13 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 1371 days ago
Earthquake alerts for Muscoy, CA
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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 it was probably too small to be felt, even directly above it. In Muscoy, 2 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: Rialto, San Bernardino, Fontana, Bloomington, Colton, Crestline.
How big was it?
This earthquake released about 11 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,400,000× the energy of this one
- Magna, Utah 2020 M 5.7 970,000× the energy of this one
- Around the size people start to feel M 3.0 86× the energy of this one
- This earthquake M 1.7 about 11 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 10,000 times the energy of this one.
Before 2016, the USGS record lists 15 earthquakes of M5 or more within 50 km; the five largest:
- 6.3 The 1992 Big Bear, California Earthquake · 50 km E of this epicentre
- 6.2 3 km SE of San Bernardino, California · 13 km SE of this epicentre
- 5.6 7km ENE of Running Springs, CA · 31 km ENE of this epicentre
- 5.5 The 1990 Upland, California Earthquake · 30 km W of this epicentre
- 5.5 11km SSE of Big Bear Lake, California · 47 km E 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 34.1615, -117.3673. 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 | 82 km (51 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
53 earthquakes have been recorded within 50 km since this one.
- 1.5 7km SSW of Lytle Creek, CA
- 1.7 6km SSW of Redlands, CA
- 1.9 6 km SSE of Home Gardens, CA
- 1.7 2km SSE of Loma Linda, CA
- 1.6 3km ESE of Home Gardens, CA
- 1.5 12km ENE of North Tustin, CA
- 1.6 1km ESE of Redlands, CA
- 1.7 7km NNE of Fontana, CA
- 1.5 3km SSW of Running Springs, CA
- 2.4 5km NW of Big Bear City, CA
- 1.7 10km WSW of Corona, CA
- 2.1 4km SW of Lytle Creek, CA
- 1.7 0km NW of Loma Linda, CA
- 1.5 2km S of Home Gardens, CA
- 2.3 9km NE 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
- 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.