Earthquake · reviewed by a seismologist
M 1.9md
Earthquake near Hydesville, CA
No earthquake was likely felt in Hydesville in the 24 hours to 6:22 am PST (14:22 UTC). The last one was M 5.0, 127 km (79 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 Hydesville
This page: a magnitude 1.9 earthquake was recorded 13 km (8 mi) east-northeast of Hydesville, CA, at 8:17 pm PDT on 27 October 2021 (03:17 UTC), 21 km deep.
USGS: 13km ENE of Hydesville, CA
- When
- 8:17 pm PDT on 27 October 2021 ()
- Where
- 13 km (8 mi) east-northeast of Hydesville, CA · earthquakes near Hydesville
- Magnitude
- M 1.9 (md)
- Depth
- 21 km below the surface
- Felt
- no reports yet
- Nearest
- Humboldt County, 12 km NNE
- Nearest mapped fault
- Little Salmon fault, 7 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 1830 days ago
Earthquake alerts for Hydesville, CA
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This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.
At this magnitude and depth it was probably too small to be felt, even directly above it. In Hydesville, 13 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.
Earthquakes near other towns within 30 km: Fortuna, Rio Dell, Pine Hills, Humboldt Hill, Cutten, Myrtletown.
How big was it?
This earthquake released about 22 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 680,000× the energy of this one
- Magna, Utah 2020 M 5.7 480,000× the energy of this one
- Around the size people start to feel M 3.0 43× the energy of this one
- This earthquake M 1.9 about 22 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 5.6 on 2019-06-23 — about 320,000 times the energy of this one.
Before 2016, the USGS record lists 25 earthquakes of M5 or more within 50 km; the five largest:
- 7.2 The 1992 Petrolia, California Earthquake · 37 km SW of this epicentre
- 6.5 The 1932 Eureka, California Earthquake · 31 km WNW of this epicentre
- 6.4 The 1954 Eureka-Arcata, California Earthquake · 28 km NNE of this epicentre
- 6.0 Near Rio Dell, California · 23 km WSW of this epicentre
- 6.0 30 km SSW of Scotia, California · 48 km SW 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 40.6018, -123.9587. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Humboldt County, CA | 12 km (7 mi) | NNE | earthquakes near Humboldt County |
| Trinity County, CA | 71 km (44 mi) | E | earthquakes near Trinity 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.
- 2.1 9km NNE of Petrolia, CA
- 2.3 9km NNE of Petrolia, CA
- 1.8 6km NE of Petrolia, CA
- 2.6 11km WSW of Rio Dell, CA
- 2.6 5km NNW of Petrolia, CA
- 2.8 10km SSE of Ferndale, CA
- 1.9 15km NNW of Petrolia, CA
- 2.8 12km NNW of Petrolia, CA
- 2.9 9km N of Petrolia, CA
- 1.8 6km NNW of Petrolia, CA
- 2.3 12km SW of Rio Dell, CA
- 2.7 11km N of Petrolia, CA
- 2.6 9km S of Ferndale, CA
- 2.7 9km SW of Petrolia, CA
- 2.6 8km N 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.