QuakeIndex

Earthquake · reviewed by a seismologist

M 4.5mw

8 km ESE of Mad River, California

· 36 km deep · released about 82 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Trinity County 34 kmHumboldt County 53 kmTehama County 106 kmMendocino 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 4.5 (mw)
Depth
36 km below the surface
Felt
136 reports · strongest reported intensity IV
Measured shaking
intensity III (ShakeMap)
USGS impact alert
green
Nearest
Trinity County, 34 km NE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3480 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 136 people have reported feeling it to USGS.

How big was it?

This earthquake released about 82 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 2,100× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 92× the energy of this one
  3. Magna, Utah 2020 M 5.7 65× the energy of this one
  4. This earthquake M 4.5 about 82 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 170× 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 40.4365, -123.4078. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Trinity County, CA 34 km (21 mi) SW of here earthquakes near Trinity County
Humboldt County, CA 53 km (33 mi) SE of here earthquakes near Humboldt County
Tehama County, CA 106 km (66 mi) WNW of here earthquakes near Tehama County
Mendocino County, CA 112 km (69 mi) N of here earthquakes near Mendocino County
Shasta County, CA 121 km (75 mi) WSW of here earthquakes near Shasta County
Glenn County, CA 126 km (78 mi) NW of here earthquakes near Glenn County

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

Aftershocks so far

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

  1. 1.7 19 km NNE of Redcrest, California
  2. 2.0 32 km ESE of Ruth, California
  3. 1.8 15 km E of Hydesville, California
  4. 2.5 1 km W of Trinity Village, California
  5. 1.7 24 km SE of Alderpoint, California
  6. 1.7 17 km ENE of Hydesville, California
  7. 1.6 15 km WNW of Mad River, California
  8. 2.1 15 km ENE of Hydesville, California
  9. 1.9 19 km E of Hydesville, California
  10. 2.1 13 km SSW of Douglas City, California
  11. 2.0 9 km WSW of Burnt Ranch, California
  12. 2.9 12 km WSW of Mad River, California
  13. 1.9 13 km N of Alderpoint, California
  14. 2.2 14 km WSW of Mad River, California
  15. 1.7 26 km SE of Alderpoint, California

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.