Earthquake · reviewed by a seismologist
M 1.7md
Earthquake near Ferndale, CA
No earthquake was likely felt in Ferndale in the 24 hours to 2:45 am PST (10:45 UTC). The last one was M 5.0, 113 km (70 mi) W, at 8:56 pm PST on 4 November 2026, estimated intensity III (weak) in town; 145 felt reports to USGS. Every earthquake near Ferndale
This page: a magnitude 1.7 earthquake was recorded 47 km (29 mi) southwest of Ferndale, CA, at 3:55 am PDT on 9 July 2023 (10:55 UTC), 13 km deep.
USGS: 32km W of Petrolia, CA
- When
- 3:55 am PDT on 9 July 2023 ()
- Where
- 47 km (29 mi) southwest of Ferndale, CA · earthquakes near Ferndale
- Magnitude
- M 1.7 (md)
- Depth
- 13 km below the surface
- Felt
- no reports yet
- Nearest
- Humboldt County, 78 km NE
- Nearest mapped fault
- Mattole Canyon fault, 19 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 1221 days ago
Earthquake alerts for Ferndale, CA
Get a notification in this browser when USGS records an earthquake near Ferndale, CA. No account or email needed.
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 2 km (1 mi) from the epicentre. In Ferndale, 47 km away, the estimate is intensity I (not felt). 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 12 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 1,300,000× the energy of this one
- Magna, Utah 2020 M 5.7 900,000× the energy of this one
- Around the size people start to feel M 3.0 80× the energy of this one
- This earthquake M 1.7 about 12 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 10,000,000 times the energy of this one.
Before 2016, the USGS record lists 41 earthquakes of M5 or more within 50 km; the five largest:
- 7.2 The 1992 Petrolia, California Earthquake · 37 km E of this epicentre
- 6.6 32 km SW of Ferndale, California · 15 km NE of this epicentre
- 6.5 30 km WSW of Ferndale, California · 19 km NNE of this epicentre
- 6.5 The 2010 Eureka, California Earthquake · 41 km N of this epicentre
- 6.0 Near Rio Dell, California · 46 km ENE 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 40.2808, -124.6633. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Humboldt County, CA | 78 km (49 mi) | NE | earthquakes near Humboldt County |
| Mendocino County, CA | 141 km (87 mi) | SE | earthquakes near Mendocino County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
54 earthquakes have been recorded within 50 km since this one.
- 1.9 15 km SE of Petrolia, CA
- 1.6 14 km SE of Petrolia, CA
- 2.2 14 km WSW of Ferndale, CA
- 1.7 8 km S of Rio Dell, CA
- 1.8 15 km SW of Ferndale, CA
- 2.1 10 km SW of Petrolia, CA
- 2.5 23 km W of Petrolia, CA
- 2.1 13 km WSW of Ferndale, CA
- 1.8 4 km NE of Petrolia, CA
- 1.5 10 km WNW of Petrolia, CA
- 2.0 13 km WSW of Ferndale, CA
- 3.1 23 km W of Petrolia, CA
- 2.3 14 km WSW of Ferndale, CA
- 1.6 2 km NE of Petrolia, CA
- 2.0 4 km E 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.