Earthquake · reviewed by a seismologist
M 2.3md
Earthquake near Fortuna, CA
No earthquake was likely felt in Fortuna in the 24 hours to 11:43 pm PST (07:43 UTC). The last one was M 5.0, 123 km (76 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 Fortuna
This page: a magnitude 2.3 earthquake was recorded 40 km (25 mi) south-southwest of Fortuna, CA, at 7:02 pm PST on 23 December 2017 (03:02 UTC), 20 km deep.
USGS: 9km WSW of Petrolia, CA
- When
- 7:02 pm PST on 23 December 2017 ()
- Where
- 40 km (25 mi) south-southwest of Fortuna, CA · earthquakes near Fortuna
- Magnitude
- M 2.3 (md)
- Depth
- 20 km below the surface
- Felt
- no reports yet
- Nearest
- Humboldt County, 61 km NE
- Nearest mapped fault
- Mattole Canyon fault, 5 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 3239 days ago
Earthquake alerts for Fortuna, 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, people at rest would likely notice it out to about 3 km (2 mi) from the epicentre. In Fortuna, 40 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.
How big was it?
This earthquake released about 91 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 170,000× the energy of this one
- Magna, Utah 2020 M 5.7 120,000× the energy of this one
- Around the size people start to feel M 3.0 10× the energy of this one
- This earthquake M 2.3 about 91 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 4.4 on 2016-01-02 — about 1,500 times the energy of this one.
Before 2016, the USGS record lists 37 earthquakes of M5 or more within 50 km; the five largest:
- 7.2 The 1992 Petrolia, California Earthquake · 14 km ENE of this epicentre
- 6.6 32 km SW of Ferndale, California · 18 km NW of this epicentre
- 6.5 30 km WSW of Ferndale, California · 23 km NW of this epicentre
- 6.5 The 2010 Eureka, California Earthquake · 49 km NNW of this epicentre
- 6.0 Near Rio Dell, California · 28 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 40.2843, -124.3803. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Humboldt County, CA | 61 km (38 mi) | NE | earthquakes near Humboldt County |
| Trinity County, CA | 114 km (71 mi) | ENE | earthquakes near Trinity County |
| Mendocino County, CA | 124 km (77 mi) | SE | 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.
- 2.4 35km W of Petrolia, CA
- 2.4 20km WNW of Petrolia, CA
- 2.4 11km WSW of Rio Dell, CA
- 2.5 17km ESE of Hydesville, CA
- 1.9 52km WNW of Petrolia, CA
- 1.8 12km SSE of Rio Dell, CA
- 2.5 20km WNW of Petrolia, CA
- 1.9 11km S of Rio Dell, CA
- 2.5 48km WNW of Petrolia, CA
- 2.3 25km WNW of Petrolia, CA
- 1.7 19km NW of Petrolia, CA
- 2.9 18km NW of Petrolia, CA
- 2.2 10km S of Ferndale, CA
- 2.5 18km WNW of Petrolia, CA
- 4.7 22km 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.