Earthquake · reviewed by a seismologist
M 1.7ml
Earthquake near Anaheim, CA
No earthquake was likely felt in Anaheim in the 24 hours to 8:03 am PST (16:03 UTC). The last one was M 3.2, 26 km (16 mi) WSW, at 12:44 am PDT on 9 October 2026, estimated intensity II (weak) in town; 1,090 felt reports to USGS. Every earthquake near Anaheim
This page: a magnitude 1.7 earthquake was recorded 6 km (3 mi) east of Anaheim, CA, at 4:22 am PDT on 31 May 2021 (11:22 UTC), 5.2 km deep.
USGS: 3km E of Anaheim, CA
5 km (3 mi) N of Orange, CA · 55 km (34 mi) ESE of Los Angeles, CA
- When
- 4:22 am PDT on 31 May 2021 ()
- Where
- 6 km (3 mi) east of Anaheim, CA · earthquakes near Anaheim
- Magnitude
- M 1.7 (ml)
- Depth
- 5.2 km below the surface
- Felt
- no reports yet
- Nearest
- Orange County, 19 km SSE
- Nearest mapped fault
- Puente Hills blind thrust system, 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 1988 days ago
Earthquake alerts for Anaheim, CA
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Alerts are on for .
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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 11 km (7 mi) from the epicentre. In Anaheim, 6 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: Placentia 5 km, intensity II · Orange 5 km, intensity II · Anaheim 6 km, intensity II · Yorba Linda 7 km, intensity II · Fullerton 8 km, intensity II · North Tustin 9 km, intensity II · Santa Ana 10 km, intensity II · Tustin 10 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 10 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 1,500,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,000,000× the energy of this one
- Around the size people start to feel M 3.0 92× the energy of this one
- This earthquake M 1.7 about 10 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 4.5 on 2020-09-19 — about 19,000 times the energy of this one.
Before 2016, the USGS record lists 15 earthquakes of M5 or more within 50 km; the five largest:
- 6.4 The 1933 Long Beach, California Earthquake · 26 km SSW of this epicentre
- 6.0 The 1910 Lake Elsinore, California Earthquake · 44 km ESE of this epicentre
- 5.9 The 1987 Whittier Narrows, California Earthquake · 33 km NW of this epicentre
- 5.5 The 1990 Upland, California Earthquake · 37 km NNE of this epicentre
- 5.4 5km S of Chino Hills, CA · 15 km NNE 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 33.8335, -117.8537. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Orange County, CA | 19 km (12 mi) | SSE | earthquakes near Orange County |
| Los Angeles County, CA | 55 km (34 mi) | NW | earthquakes near Los Angeles County |
| Ventura County, CA | 131 km (82 mi) | WNW | earthquakes near Ventura 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
52 earthquakes have been recorded within 50 km since this one.
- 1.7 6km SSE of Home Gardens, CA
- 1.8 1km NNW of La Puente, CA
- 2.5 3km WSW of Fontana, CA
- 1.8 2km SE of Home Gardens, CA
- 1.5 2km WSW of Costa Mesa, CA
- 1.8 4km SE of Home Gardens, CA
- 2.1 0km W of Brea, CA
- 1.6 1km NNW of South Gate, CA
- 1.6 22km SSW of Seal Beach, CA
- 2.5 4km SE of Ontario, CA
- 1.7 6km NW of Corona, CA
- 2.0 9km WSW of Lytle Creek, CA
- 1.9 3km WSW of Compton, CA
- 1.7 5km ENE of Villa Park, CA
- 1.8 11km NNE of Trabuco Canyon, 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.