QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near Covelo, CA

No earthquake was likely felt in Covelo in the 24 hours to 9:12 pm PST (05:12 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 1.8 earthquake was recorded 7 km (5 mi) east-northeast of Covelo, CA, at 8:35 am PDT on 11 July 2018 (15:35 UTC), 8.1 km deep.

USGS: 7km ENE of Covelo, CA

8:35 am PDT, Jul 11, 2018 · · 8.1 km deep · released about 15 lb of TNT

10 km30 km60 km120 km N Mendocino County 48 kmGlenn County 69 kmLake County 86 kmTehama County 87 kmTrinity County 93 kmColusa County 106 kmHumboldt County 119 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
8:35 am PDT on 11 July 2018 ()
Where
7 km (5 mi) east-northeast of Covelo, CA · earthquakes near Covelo
Magnitude
M 1.8 (md)
Depth
8.1 km below the surface
Felt
no reports yet
Nearest
Mendocino County, 48 km SSW
Nearest mapped fault
Bartlett Springs fault system, 2 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3044 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 11 km (7 mi) from the epicentre. In Covelo, 7 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: Covelo 7 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
  3. Around the size people start to feel M 3.0 63× the energy of this one
  4. This earthquake M 1.8 about 15 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 4.3 on 2017-12-14 — about 4,900 times the energy of this one.

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

  1. 5.9 9 km S of Leggett, California · 49 km W 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 39.8123, -123.1665. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Mendocino County, CA 48 km (30 mi) SSW earthquakes near Mendocino County
Glenn County, CA 69 km (43 mi) ESE earthquakes near Glenn County
Lake County, CA 86 km (54 mi) SSE earthquakes near Lake County
Tehama County, CA 87 km (54 mi) ENE earthquakes near Tehama County
Trinity County, CA 93 km (58 mi) N earthquakes near Trinity County
Colusa County, CA 106 km (66 mi) SE earthquakes near Colusa County

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

Aftershocks so far

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

  1. 2.1 32km NNW of Covelo, CA
  2. 2.4 9km ESE of Willits, CA
  3. 1.8 34km ENE of Covelo, CA
  4. 2.5 8km ESE of Willits, CA
  5. 2.0 9km ESE of Willits, CA
  6. 1.9 21km N of Laytonville, CA
  7. 2.6 9km NNE of Brooktrails, CA
  8. 1.8 15km NW of Alder Springs, CA
  9. 1.6 7km ENE of Willits, CA
  10. 2.5 20km NNW of Alder Springs, CA
  11. 1.6 20km NNW of Alder Springs, CA
  12. 2.1 20km NNW of Alder Springs, CA
  13. 2.3 7km E of Willits, CA
  14. 1.6 7km ENE of Willits, CA
  15. 1.8 13km SSE 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.