QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mw

19km W of Delta, B.C., MX

Yes. A magnitude 4.0 earthquake was recorded 19km W of Delta, B.C., MX, 84 km (52 mi) WSW of Yuma, AZ, at 4:30 pm PST on 21 December 2020 (00:30 UTC), 15 km deep. 46 people have reported feeling it to USGS.

84 km (52 mi) WSW of Yuma, AZ

· 15 km deep · released about 18 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Imperial County 78 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 4.0 (mw)
Depth
15 km below the surface
Felt
46 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Nearest
Imperial County, 78 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1942 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 100 km (62 mi) from the epicentre. 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: Calexico 39 km, intensity III. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 18 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 9,400× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 420× the energy of this one
  3. Magna, Utah 2020 M 5.7 300× the energy of this one
  4. This earthquake M 4.0 about 18 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 38× 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.

For this area

The largest earthquake within 50 km in our catalogue was M 4.8 on 2018-11-19 — about 14 times the energy of this one.

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 32.3372, -115.3908. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Imperial County, CA 78 km (49 mi) N earthquakes near Imperial County

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

Aftershocks so far

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

  1. 2.2 8km ESE of Puebla, B.C., MX
  2. 2.5 16km WNW of Progreso, B.C., MX
  3. 2.3 8km S of Progreso, B.C., MX
  4. 2.0 7km E of Puebla, B.C., MX
  5. 1.8 8km ESE of Puebla, B.C., MX
  6. 1.6 15km WNW of Progreso, B.C., MX
  7. 1.6 15km WNW of Progreso, B.C., MX
  8. 2.2 15km WNW of Progreso, B.C., MX
  9. 2.3 16km WNW of Progreso, B.C., MX
  10. 2.3 7km SSE of Mexicali, B.C., MX
  11. 2.2 3km NW of Delta, B.C., MX
  12. 2.2 18km WSW of Delta, B.C., MX
  13. 1.7 7km WSW of Holtville, CA
  14. 2.2 4km NNW of Delta, B.C., MX
  15. 2.3 6km NW of Delta, B.C., MX

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.