QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

Earthquake near Rio Dell, CA

No earthquake was likely felt in Rio Dell in the 24 hours to 11:03 pm PST (07:03 UTC). The last one was M 5.0, 126 km (78 mi) W, at 8:56 pm PST on 4 November 2026, estimated intensity II (weak) in town; 145 felt reports to USGS. Every earthquake near Rio Dell

This page: a magnitude 1.6 earthquake was recorded 9 km (6 mi) west of Rio Dell, CA, at 6:35 am PDT on 22 August 2019 (13:35 UTC), 22 km deep.

USGS: 9km W of Rio Dell, CA

6:35 am PDT, Aug 22, 2019 · · 22 km deep · released about 6.6 lb of TNT

Every earthquake near Rio Dell Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 34 kmTrinity County 94 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
6:35 am PDT on 22 August 2019 ()
Where
9 km (6 mi) west of Rio Dell, CA · earthquakes near Rio Dell
Magnitude
M 1.6 (md)
Depth
22 km below the surface
Felt
no reports yet
Nearest
Humboldt County, 34 km NE
Nearest mapped fault
Little Salmon 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 2633 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 Rio Dell, 9 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: Ferndale, Hydesville, Fortuna, Humboldt Hill, Pine Hills.

How big was it?

This earthquake released about 6.6 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,300,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,600,000× the energy of this one
  3. Around the size people start to feel M 3.0 140× the energy of this one
  4. This earthquake M 1.6 about 6.6 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 5.6 on 2019-06-23 — about 1,100,000 times the energy of this one.

Before 2016, the USGS record lists 37 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 The 1992 Petrolia, California Earthquake · 17 km S of this epicentre
  2. 6.6 32 km SW of Ferndale, California · 31 km WSW of this epicentre
  3. 6.5 The 1932 Eureka, California Earthquake · 28 km NNW of this epicentre
  4. 6.5 30 km WSW of Ferndale, California · 31 km W of this epicentre
  5. 6.5 The 2010 Eureka, California Earthquake · 45 km WNW 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 40.4848, -124.2103. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Humboldt County, CA 34 km (21 mi) NE earthquakes near Humboldt County
Trinity County, CA 94 km (59 mi) ENE earthquakes near Trinity County
Mendocino County, CA 134 km (83 mi) SSE earthquakes near Mendocino 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. 2.2 32km W of Petrolia, CA
  2. 2.3 18km WNW of Petrolia, CA
  3. 1.6 7km WSW of Petrolia, CA
  4. 2.1 13km SE of Rio Dell, CA
  5. 1.8 6km WNW of Ferndale, CA
  6. 1.8 20km SSE of Rio Dell, CA
  7. 2.1 16km WNW of Petrolia, CA
  8. 2.1 16km WNW of Petrolia, CA
  9. 2.4 16km WNW of Petrolia, CA
  10. 2.8 19km WSW of Petrolia, CA
  11. 1.7 17km ENE of Hydesville, CA
  12. 3.2 3km ESE of Petrolia, CA
  13. 1.7 12km ENE of Petrolia, CA
  14. 2.2 24km W of Petrolia, CA
  15. 1.6 36km WNW of Petrolia, 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.