Earthquake · reviewed by a seismologist
M 1.7md
Earthquake near Rio Dell, CA
No earthquake was likely felt in Rio Dell in the 24 hours to 11:06 pm PST (07:06 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 1.7 earthquake was recorded 10 km (6 mi) southeast of Rio Dell, CA, at 3:08 am PDT on 20 July 2024 (10:08 UTC), 24 km deep.
USGS: 10 km SE of Rio Dell, CA
- When
- 3:08 am PDT on 20 July 2024 ()
- Where
- 10 km (6 mi) southeast of Rio Dell, CA · earthquakes near Rio Dell
- Magnitude
- M 1.7 (md)
- Depth
- 24 km below the surface
- Felt
- no reports yet
- Nearest
- Humboldt County, 30 km NNE
- Nearest mapped fault
- Little Salmon fault, 10 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 844 days ago
Earthquake alerts for Rio Dell, CA
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Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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, 10 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: Hydesville, Fortuna, Ferndale.
How big was it?
This earthquake released about 10 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,500,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
- Around the size people start to feel M 3.0 95× the energy of this one
- This earthquake M 1.7 about 10 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 6.4 on 2022-12-20 — about 12,000,000 times the energy of this one.
Before 2016, the USGS record lists 28 earthquakes of M5 or more within 50 km; the five largest:
- 7.2 The 1992 Petrolia, California Earthquake · 22 km SW of this epicentre
- 6.6 32 km SW of Ferndale, California · 46 km W of this epicentre
- 6.5 The 1932 Eureka, California Earthquake · 39 km NW of this epicentre
- 6.5 30 km WSW of Ferndale, California · 47 km W of this epicentre
- 6.4 The 1954 Eureka-Arcata, California Earthquake · 45 km NNE 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 40.4485, -124.0160. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Humboldt County, CA | 30 km (18 mi) | NNE | earthquakes near Humboldt County |
| Trinity County, CA | 79 km (49 mi) | ENE | earthquakes near Trinity County |
| Mendocino County, CA | 123 km (76 mi) | SSE | earthquakes near Mendocino County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
52 earthquakes have been recorded within 50 km since this one.
- 1.6 22 km WNW of Petrolia, CA
- 1.7 21 km WNW of Petrolia, CA
- 1.7 7 km WNW of Petrolia, CA
- 2.0 22 km NW of Petrolia, CA
- 2.2 23 km W of Petrolia, CA
- 1.9 3 km ESE of Fortuna, CA
- 2.2 20 km NW of Petrolia, CA
- 2.2 15 km WSW of Ferndale, CA
- 1.8 13 km SSE of Petrolia, CA
- 1.8 4 km NNW of Redway, CA
- 2.1 10 km W of Rio Dell, CA
- 1.8 11 km NW of Petrolia, CA
- 1.9 8 km WSW of Petrolia, CA
- 1.6 26 km ESE of Rio Dell, CA
- 1.6 12 km 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
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.