QuakeIndex

Earthquake · reviewed by a seismologist

M 2.3md

Earthquake near Covelo, CA

No earthquake was likely felt in Covelo in the 24 hours to 1:29 am PST (09:29 UTC). The last one was M 2.2, 9 km (6 mi) N, at 3:31 pm PST on 10 November 2026, estimated intensity II (weak) in town. Every earthquake near Covelo

This page: a magnitude 2.3 earthquake was recorded 38 km (24 mi) north-northeast of Covelo, CA, at 1:39 pm PDT on 17 April 2021 (20:39 UTC), 40 km deep.

USGS: 38km NNE of Covelo, CA

1:39 pm PDT, Apr 17, 2021 · · 40 km deep · released about 79 lb of TNT

10 km30 km60 km120 km N Trinity County 61 kmTehama County 69 kmGlenn County 78 kmMendocino County 82 kmHumboldt County 101 kmShasta County 112 kmLake County 113 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
1:39 pm PDT on 17 April 2021 ()
Where
38 km (24 mi) north-northeast of Covelo, CA · earthquakes near Covelo
Magnitude
M 2.3 (md)
Depth
40 km below the surface
Felt
no reports yet
Nearest
Trinity County, 61 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2034 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 Covelo, 38 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.

How big was it?

This earthquake released about 79 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 190,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 130,000× the energy of this one
  3. Around the size people start to feel M 3.0 12× the energy of this one
  4. This earthquake M 2.3 about 79 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 2016-08-28 — about 2,100 times the energy of this one.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.5 33 km NW of Rancho Tehama Reserve, California · 30 km ENE 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 40.1007, -123.0443. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Trinity County, CA 61 km (38 mi) N earthquakes near Trinity County
Tehama County, CA 69 km (43 mi) E earthquakes near Tehama County
Glenn County, CA 78 km (48 mi) SE earthquakes near Glenn County
Mendocino County, CA 82 km (51 mi) SSW earthquakes near Mendocino County
Humboldt County, CA 101 km (62 mi) NW earthquakes near Humboldt County
Shasta County, CA 112 km (70 mi) NE earthquakes near Shasta County

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

Aftershocks so far

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

  1. 1.9 12km WNW of Alder Springs, CA
  2. 2.4 13km WNW of Alder Springs, CA
  3. 2.6 12km WNW of Alder Springs, CA
  4. 2.1 13km WNW of Alder Springs, CA
  5. 2.0 12km WNW of Alder Springs, CA
  6. 2.2 12km WNW of Alder Springs, CA
  7. 1.9 12km WNW of Alder Springs, CA
  8. 1.7 13km WNW of Alder Springs, CA
  9. 3.0 12km WNW of Alder Springs, CA
  10. 2.7 12km WNW of Alder Springs, CA
  11. 2.0 12km WNW of Alder Springs, CA
  12. 1.9 41km NE of Covelo, CA
  13. 2.0 41km NE of Covelo, CA
  14. 1.9 11km N of Covelo, CA
  15. 1.9 26km N of Laytonville, 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.