QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9mw

23km ESE of Anza, CA

· 14 km deep · released about 9.3 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Riverside County 50 kmSan Diego County 58 kmImperial County 112 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
Magnitude
M 3.9 (mw)
Depth
14 km below the surface
Felt
2570 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
Nearest
Riverside County, 50 km NE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1630 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 2570 people have reported feeling it to USGS.

How big was it?

This earthquake released about 9.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 18,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 810× the energy of this one
  3. Magna, Utah 2020 M 5.7 580× the energy of this one
  4. This earthquake M 3.9 about 9.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 19× more

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.

Where

Epicentre 33.4688, -116.4430. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Riverside County, CA 50 km (31 mi) SW of here earthquakes near Riverside County
San Diego County, CA 58 km (36 mi) NNE of here earthquakes near San Diego County
Imperial County, CA 112 km (69 mi) WNW of here earthquakes near Imperial County

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

Aftershocks so far

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

  1. 1.5 13km WNW of Anza, CA
  2. 2.0 10km NNW of Idyllwild, CA
  3. 1.9 23km SSW of La Quinta, CA
  4. 2.0 23km ESE of Anza, CA
  5. 1.7 23km SSW of La Quinta, CA
  6. 1.5 24km ESE of Anza, CA
  7. 1.7 23km ESE of Anza, CA
  8. 1.6 9km SSW of Idyllwild, CA
  9. 2.3 23km ESE of Anza, CA
  10. 1.5 23km SSW of La Quinta, CA
  11. 2.2 6km SSW of Warner Springs, CA
  12. 2.0 23km ESE of Anza, CA
  13. 1.8 24km ESE of Anza, CA
  14. 1.5 19km SE of Anza, CA
  15. 4.0 5km WSW of Palomar Observatory, 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.

For this area

The largest earthquake within 50 km in our catalogue was M 5.2 on 2016-06-10 — it released about 99 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

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