Earthquake near Hydesville, CA

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 31 km (19 mi) from the epicentre. In Hydesville, 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.

Likely felt in: Rio Dell 13 km, intensity II · Fortuna 16 km, intensity II · Ferndale 24 km, intensity II · Humboldt Hill 25 km, intensity II · Eureka 31 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 990 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 340,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 15,000× the energy of this one
3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
4. This earthquake M 3.0 about 990 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 120,000 times the energy of this one.

Before 2016, the USGS record lists 29 earthquakes of M5 or more within 50 km; the five largest:

1. 7.2 The 1992 Petrolia, California Earthquake · 33 km SW of this epicentre Apr 25, 1992
2. 6.5 The 1932 Eureka, California Earthquake · 32 km NW of this epicentre Jun 6, 1932
3. 6.4 The 1954 Eureka-Arcata, California Earthquake · 32 km NNE of this epicentre Dec 21, 1954
4. 6.0 Near Rio Dell, California · 20 km WSW of this epicentre Oct 29, 1909
5. 6.0 31 km NW of Shelter Cove, California · 47 km SW of this epicentre Sep 22, 1952

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 40.5657, -123.9767. Map © OpenStreetMap contributors.

Nearby places

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.

1. 2.3 5km ESE of Hydesville, CA 04:18 UTC
2. 2.5 10km NE of Hydesville, CA 04:15 UTC
3. 2.5 3km SSW of Fortuna, CA 03:44 UTC
4. 2.3 3km SE of Ferndale, CA 02:56 UTC
5. 2.2 10km NNE of Hydesville, CA 02:44 UTC
6. 2.2 5km SE of Ferndale, CA 01:38 UTC
7. 2.0 16km WSW of Ferndale, CA 01:30 UTC
8. 2.5 14km WSW of Ferndale, CA 01:14 UTC
9. 3.0 19km WSW of Ferndale, CA 01:07 UTC
10. 2.4 7km WSW of Ferndale, CA 00:33 UTC
11. 2.7 3km ENE of Hydesville, CA 00:15 UTC
12. 1.8 9km E of Hydesville, CA 23:41 UTC
13. 2.0 7km SW of Ferndale, CA 23:35 UTC
14. 1.7 14km ENE of Hydesville, CA 23:26 UTC
15. 1.8 2km NW of Hydesville, CA 23:22 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 07:40 UTC. 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.