QuakeIndex

Earthquake · reviewed by a seismologist

M 3.8mw

Earthquake near Fortuna, CA

No earthquake was likely felt in Fortuna in the 24 hours to 4:45 am PST (12:45 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 3.8 earthquake was recorded 46 km (28 mi) southwest of Fortuna, CA, at 9:55 pm PST on 1 March 2019 (05:55 UTC), 20 km deep. 43 people have reported feeling it to USGS.

USGS: 21km W of Petrolia, CA

9:55 pm PST, Mar 1, 2019 · · 20 km deep · released about 7.3 tons of TNT

Every earthquake near Fortuna Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Humboldt County 68 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
9:55 pm PST on 1 March 2019 ()
Where
46 km (28 mi) southwest of Fortuna, CA · earthquakes near Fortuna
Magnitude
M 3.8 (mw)
Depth
20 km below the surface
Felt
43 reports · strongest reported intensity III
Measured shaking
intensity III (ShakeMap)
Nearest
Humboldt County, 68 km NE
Nearest mapped fault
Mattole Canyon fault, 8 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 2739 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 80 km (50 mi) from the epicentre. In Fortuna, 46 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.

Likely felt in: Ferndale 38 km, intensity II · Rio Dell 42 km, intensity II · Fortuna 46 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 7.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 23,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 730× the energy of this one
  4. This earthquake M 3.8 about 7.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 15× more

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 4.7 on 2018-03-23 — about 20 times the energy of this one.

Before 2016, the USGS record lists 40 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 The 1992 Petrolia, California Earthquake · 26 km E of this epicentre
  2. 6.6 32 km SW of Ferndale, California · 10 km NNW of this epicentre
  3. 6.5 30 km WSW of Ferndale, California · 15 km NNW of this epicentre
  4. 6.5 The 2010 Eureka, California Earthquake · 42 km NNW of this epicentre
  5. 6.0 Near Rio Dell, California · 36 km NE 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 40.2985, -124.5287. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Humboldt County, CA 68 km (42 mi) NE earthquakes near Humboldt County
Mendocino County, CA 134 km (83 mi) SE earthquakes near Mendocino County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

56 earthquakes have been recorded within 50 km since this one.

  1. 1.8 5km SSW of Petrolia, CA
  2. 2.1 5km SSW of Petrolia, CA
  3. 5.6 6km SSW of Petrolia, CA
  4. 2.8 5km S of Petrolia, CA
  5. 2.1 12km WNW of Petrolia, CA
  6. 2.6 36km WNW of Petrolia, CA
  7. 2.6 32km WNW of Petrolia, CA
  8. 2.9 14km SE of Petrolia, CA
  9. 2.0 15km WSW of Petrolia, CA
  10. 2.0 24km W of Petrolia, CA
  11. 1.6 16km WNW of Petrolia, CA
  12. 2.0 11km S of Ferndale, CA
  13. 2.6 6km ESE of Hydesville, CA
  14. 2.3 14km SE of Petrolia, CA
  15. 2.6 47km W of Ferndale, 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.