QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

Earthquake near Garden Grove, CA

No earthquake was likely felt in Garden Grove in the 24 hours to 8:08 am PST (16:08 UTC). The last one was M 3.2, 23 km (14 mi) W, at 12:44 am PDT on 9 October 2026, estimated intensity II (weak) in town; 1,090 felt reports to USGS. Every earthquake near Garden Grove

This page: a magnitude 1.8 earthquake was recorded 2 km (1 mi) south of Garden Grove, CA, at 1:30 pm PDT on 28 August 2021 (20:30 UTC), 15 km deep.

USGS: 3km SSE of Garden Grove, CA

in Garden Grove, CA · 52 km (32 mi) SE of Los Angeles, CA

1:30 pm PDT, Aug 28, 2021 · · 15 km deep · released about 16 lb of TNT

Every earthquake near Garden Grove Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Orange County 18 kmLos Angeles County 57 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
1:30 pm PDT on 28 August 2021 ()
Where
2 km (1 mi) south of Garden Grove, CA · earthquakes near Garden Grove
Magnitude
M 1.8 (ml)
Depth
15 km below the surface
Felt
no reports yet
Nearest
Orange County, 18 km ESE
Nearest mapped fault
San Joaquin Hills thrust, 7 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 1900 days ago

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 Garden Grove, 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: Fountain Valley, Westminster, Stanton, Santa Ana, Orange, Anaheim.

How big was it?

This earthquake released about 16 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 930,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 660,000× the energy of this one
  3. Around the size people start to feel M 3.0 59× the energy of this one
  4. This earthquake M 1.8 about 16 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 12,000 times the energy of this one.

Before 2016, the USGS record lists 12 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.4 The 1933 Long Beach, California Earthquake · 15 km SSW of this epicentre
  2. 5.9 The 1987 Whittier Narrows, California Earthquake · 36 km NNW of this epicentre
  3. 5.5 The 1990 Upland, California Earthquake · 49 km NNE of this epicentre
  4. 5.4 5km S of Chino Hills, CA · 27 km NE of this epicentre
  5. 5.3 7km W of Newport Beach, CA · 15 km SSW 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 33.7540, -117.9455. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Orange County, CA 18 km (11 mi) ESE earthquakes near Orange County
Los Angeles County, CA 57 km (36 mi) NNW earthquakes near Los Angeles County
Ventura County, CA 128 km (80 mi) WNW earthquakes near Ventura County
San Diego County, CA 136 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

46 earthquakes have been recorded within 50 km since this one.

  1. 1.6 11km W of Corona, CA
  2. 1.5 1km SW of Rossmoor, CA
  3. 1.6 1km ESE of Baldwin Hills, CA
  4. 1.7 2km E of Carson, CA
  5. 1.9 4km SSE of Home Gardens, CA
  6. 2.1 19km NNE of Avalon, CA
  7. 1.5 2km SSW of San Dimas, CA
  8. 1.8 7km ESE of San Pedro, CA
  9. 1.7 7km SE of San Pedro, CA
  10. 2.2 4km W of Pomona, CA
  11. 1.6 4km NNE of Diamond Bar, CA
  12. 1.8 4km WSW of East Los Angeles, CA
  13. 1.5 4km SE of Home Gardens, CA
  14. 2.1 11km SSW of Rancho Palos Verdes, CA
  15. 1.6 2km ESE of Anaheim, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.