Earthquake · reviewed by a seismologist
M 2.5md
Earthquake near Ferndale, CA
No earthquake was likely felt in Ferndale in the 24 hours to 3:12 am PST (11:12 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 2.5 earthquake was recorded 27 km (17 mi) west of Ferndale, CA, at 12:57 am PDT on 28 August 2017 (07:57 UTC), 25 km deep.
USGS: 27 km W of Ferndale, California
- When
- 12:57 am PDT on 28 August 2017 ()
- Where
- 27 km (17 mi) west of Ferndale, CA · earthquakes near Ferndale
- Magnitude
- M 2.5 (md)
- Depth
- 25 km below the surface
- Felt
- no reports yet
- Nearest
- Humboldt County, 58 km ENE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 3360 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 small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
At this magnitude and depth it was probably too small to be felt, even directly above it. In Ferndale, 27 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 190 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 78,000× the energy of this one
- Magna, Utah 2020 M 5.7 55,000× the energy of this one
- Around the size people start to feel M 3.0 4.9× the energy of this one
- This earthquake M 2.5 about 190 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 710 times the energy of this one.
Before 2016, the USGS record lists 45 earthquakes of M5 or more within 50 km; the five largest:
- 7.2 The 1992 Petrolia, California Earthquake · 38 km SE of this epicentre
- 6.6 32 km SW of Ferndale, California · 18 km S of this epicentre
- 6.5 The 1932 Eureka, California Earthquake · 32 km NE of this epicentre
- 6.5 30 km WSW of Ferndale, California · 12 km S of this epicentre
- 6.5 The 2010 Eureka, California Earthquake · 15 km NW 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 40.5417, -124.5823. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Humboldt County, CA | 58 km (36 mi) | ENE | earthquakes near Humboldt County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
60 earthquakes have been recorded within 50 km since this one.
- 2.0 17km W of Petrolia, CA
- 1.6 10km WSW of Rio Dell, CA
- 2.5 31km WSW of Ferndale, CA
- 2.1 32km W of Petrolia, CA
- 1.8 5km ENE of Petrolia, CA
- 2.6 12km W of Petrolia, CA
- 2.7 33km WNW of Petrolia, CA
- 1.8 4km WSW of Rio Dell, CA
- 2.7 60km W of Petrolia, CA
- 2.9 59km W of Petrolia, CA
- 2.5 31km W of Petrolia, CA
- 2.1 20km W of Petrolia, CA
- 1.9 18km W of Petrolia, CA
- 3.0 12km WSW of Petrolia, CA
- 3.8 20km WSW 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.