QuakeIndex

Earthquake · reviewed by a seismologist

M 2.2md

Earthquake near Riverdale, CA

No earthquake was likely felt in Riverdale in the 24 hours to 7:08 am PST (15:08 UTC). The last one was M 3.3, 38 km (24 mi) S, at 6:21 am PDT on 4 August 2026, estimated intensity II (weak) in town; 2 felt reports to USGS. Every earthquake near Riverdale

This page: a magnitude 2.2 earthquake was recorded 6 km (4 mi) south-southeast of Riverdale, CA, at 8:41 pm PDT on 23 May 2021 (03:41 UTC), 15 km deep.

USGS: 6km SSE of Riverdale, CA

44 km (28 mi) S of Fresno, CA · 17 km (11 mi) WNW of Hanford, CA

8:41 pm PDT, May 23, 2021 · · 15 km deep · released about 60 lb of TNT

Every earthquake near Riverdale Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Kings County 35 kmFresno County 45 kmMadera County 92 kmTulare County 96 kmSan Benito County 115 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
8:41 pm PDT on 23 May 2021 ()
Where
6 km (4 mi) south-southeast of Riverdale, CA · earthquakes near Riverdale
Magnitude
M 2.2 (md)
Depth
15 km below the surface
Felt
no reports yet
Nearest
Kings County, 35 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1998 days ago

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 10 km (6 mi) from the epicentre. In Riverdale, 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: Lemoore 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 60 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.2 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 250,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 180,000× the energy of this one
  3. Around the size people start to feel M 3.0 16× the energy of this one
  4. This earthquake M 2.2 about 60 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 4.0 on 2018-11-27 — about 500 times the energy of this one.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.7 The 1983 Coalinga, California Earthquake · 46 km WSW of this epicentre
  2. 5.6 8 km SW of Huron, California · 40 km SW of this epicentre
  3. 5.5 11 km NNE of Coalinga, California · 45 km WSW of this epicentre
  4. 5.5 11 km NE of Coalinga, California · 44 km WSW of this epicentre
  5. 5.2 12 km NNE of Coalinga, California · 45 km WSW 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 36.3842, -119.8312. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Kings County, CA 35 km (22 mi) S earthquakes near Kings County
Fresno County, CA 45 km (28 mi) NNE earthquakes near Fresno County
Madera County, CA 92 km (57 mi) N earthquakes near Madera County
Tulare County, CA 96 km (59 mi) E earthquakes near Tulare County
San Benito County, CA 115 km (71 mi) WNW earthquakes near San Benito County
Merced County, CA 120 km (75 mi) NW earthquakes near Merced County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

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

  1. 1.9 3km SW of Huron, CA
  2. 1.5 13km SW of Huron, CA
  3. 1.8 6km NNE of Avenal, CA
  4. 2.6 10km NNE of Avenal, CA
  5. 1.8 11km ENE of Coalinga, CA
  6. 2.3 10km ENE of Coalinga, CA
  7. 2.1 19km ESE of Kettleman City, CA
  8. 2.1 19km ESE of Kettleman City, CA
  9. 1.9 18km ESE of Kettleman City, CA
  10. 2.0 18km ESE of Kettleman City, CA
  11. 1.9 21km ESE of Kettleman City, CA
  12. 1.8 20km ESE of Kettleman City, CA
  13. 1.6 20km ESE of Kettleman City, CA
  14. 1.7 11km NNE of Kettleman City, CA
  15. 2.2 12km SE of San Joaquin, 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.