QuakeScout
Magnitude7.1

Reviewed by USGSCalifornia Earthquake105y ago

M7.1 earthquake in The 1923 Humboldt County, California Earthquake

Monday, January 22, 1923, 09:04:21 UTC · 40.482°N, 125.034°W

A magnitude 7.1 earthquake struck in The 1923 Humboldt County, California Earthquake on Monday, January 22, 1923, 09:04:21 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.4 on January 31, 1922.

Magnitude
7.1
Major · mw
Depth
15 km
Shallow
Felt reports
0
Did You Feel It?
Est. shaking
V
Moderate (ShakeMap)
PAGER alert
None
Not issued
Tsunami
No flag
USGS feed

Outlined circle: this earthquakeColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

722 kilotons of TNT

That is about 48 times the Hiroshima bomb. It released about 1,514 times the energy of a magnitude 5.0.

Tectonic setting

14 km

from the nearest mapped plate boundary, between the Juan de Fuca and North American plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

15 km

Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.

Did You Feel It?

Where it was felt

No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.

I felt it — report to USGS ↗

USGS PAGER estimate

Who was exposed to shaking

USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.

After the main event

Aftershocks within 200 km

USGS lists 1 M2.5+ earthquake within 200 km in the following 30 days. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M4M5M6M71h6h1d3d7d14d30dMainshock M7.1
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

    Regional history

    Past M5+ earthquakes within 300 km

    USGS lists 12 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

    1. 7.4123 km W of Big Lagoon, CaliforniaJanuary 31, 1922 · 92 km NW of this epicenter
    2. 6.552 km WNW of Big Lagoon, CaliforniaJuly 15, 1918 · 97 km N of this epicenter
    3. 6.4187 km W of Trinidad, CaliforniaDecember 31, 1915 · 137 km NW of this epicenter
    4. 6.4off the coast of Northern CaliforniaJune 10, 1917 · 248 km W of this epicenter
    5. 6.3237 km WSW of Ferndale, CaliforniaMay 6, 1915 · 171 km W of this epicenter

    History · NOAA

    Deadliest earthquakes in this area

    NOAA’s significant-earthquake database lists 8 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

    1. 1865

      Fort Humboldt, Eureka

      1 Oct 1865 · 73 km away · intensity IX

      Moderate damage ($1–5M)

    2. 1922M7.6

      Northern

      31 Jan 1922 · 70 km away

      Limited damage (under $1M)

    3. 1923M7.1

      Northern

      22 Jan 1923 · 0 km away · intensity VIII

      Limited damage (under $1M)tsunami

    4. 1873M6.7

      Northern

      23 Nov 1873 · 190 km away · intensity VIII

      Limited damage (under $1M)tsunami

    5. 1871M5.9

      Humboldt County

      2 Mar 1871 · 71 km away · intensity VII

      Limited damage (under $1M)

    6. 1898

      N Coast,Mendocino County

      14 Apr 1898 · 187 km away · intensity X

      Limited damage (under $1M)

    NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

    Nearby trackers

    Closest city pages