QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5md

Earthquake near Brooktrails, CA

No earthquake was likely felt in Brooktrails in the 24 hours to 9:10 pm PST (05:10 UTC). The last one was M 4.0, 38 km (23 mi) E, at 5:01 am PDT on 28 October 2026, estimated intensity III (weak) in town; 14 felt reports to USGS. Every earthquake near Brooktrails

This page: a magnitude 1.5 earthquake was recorded 16 km (10 mi) northeast of Brooktrails, CA, at 9:21 am PDT on 8 October 2019 (16:21 UTC), 8.4 km deep.

USGS: 16km NE of Brooktrails, CA

9:21 am PDT, Oct 8, 2019 · · 8.4 km deep · released about 6.2 lb of TNT

10 km30 km60 km120 km N Mendocino County 21 kmLake County 64 kmGlenn County 72 kmColusa County 95 kmTehama County 108 kmSonoma County 115 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
9:21 am PDT on 8 October 2019 ()
Where
16 km (10 mi) northeast of Brooktrails, CA · earthquakes near Brooktrails
Magnitude
M 1.5 (md)
Depth
8.4 km below the surface
Felt
no reports yet
Nearest
Mendocino County, 21 km WSW
Nearest mapped fault
Maacama fault, 14 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 2581 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 6 km (4 mi) from the epicentre. In Brooktrails, 16 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.

Earthquakes near other towns within 30 km: Willits, Laytonville, Covelo, Redwood Valley.

How big was it?

This earthquake released about 6.2 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,700,000× the energy of this one
  3. Around the size people start to feel M 3.0 150× the energy of this one
  4. This earthquake M 1.5 about 6.2 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 5.1 on 2016-08-10 — about 210,000 times the energy of this one.

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

  1. 5.2 6 km ESE of Talmage, California · 48 km SSE 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 39.5328, -123.2398. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Mendocino County, CA 21 km (13 mi) WSW earthquakes near Mendocino County
Lake County, CA 64 km (40 mi) SE earthquakes near Lake County
Glenn County, CA 72 km (45 mi) E earthquakes near Glenn County
Colusa County, CA 95 km (59 mi) ESE earthquakes near Colusa County
Tehama County, CA 108 km (67 mi) NE earthquakes near Tehama County
Sonoma County, CA 115 km (72 mi) SSE earthquakes near Sonoma 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 13km N of Laytonville, CA
  2. 2.8 10km NNE of Talmage, CA
  3. 2.4 13km WNW of Lake Pillsbury, CA
  4. 2.2 12km N of Laytonville, CA
  5. 1.6 6km E of Willits, CA
  6. 1.8 8km ESE of Redwood Valley, CA
  7. 1.7 16km NW of Alder Springs, CA
  8. 2.0 1km W of Redwood Valley, CA
  9. 3.5 2km W of Redwood Valley, CA
  10. 1.7 16km ESE of Lake Pillsbury, CA
  11. 2.3 13km SE of Laytonville, CA
  12. 1.6 2km E of Willits, CA
  13. 1.7 6km ENE of Redwood Valley, CA
  14. 1.6 23km SSW of Willits, CA
  15. 1.6 9km NNW of Lake Pillsbury, 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.