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The April 28, 1923 earthquake

M5.6near Samoa, California

A magnitude 5.6 earthquake, 44.0 miles off Humboldt County. The 160th strongest in California’s record since 1900, and the strongest within 50 miles since a magnitude 7.1 on January 22, 1923.

The earthquake

Magnitude
5.6
surface-wave magnitude (ms)
Depth
—
Not recorded
Local time
Saturday, April 28, 1923
18:31 PST; 02:31 UTC on Apr 29, 1923
Epicentre
41.00°N, 125.00°W
44.0 mi from Humboldt County
In California’s record
160th
strongest of 97,065 since 1900
Within 50 miles
1
county; more on this date

USGS ANSS Comprehensive Earthquake Catalog, event ushis689 (“71 km WNW of Samoa, California”). The USGS event page carries the ShakeMap, felt reports and the official summary.

Counties and cities within 50 miles

Distance from the epicentre to each county boundary (zero when inside) and to each city centre.

Counties

Cities, largest first

Earthquakes around the epicentre

1,321 earthquakes of magnitude 3 or more within 50 miles of this epicentre since 1973.

Earthquakes of magnitude 3 or more within 50 miles of the epicentre, by year 1973: 2 1974: 21 1975: 38 1976: 37 1977: 35 1978: 35 1979: 29 1980: 76 1981: 47 1982: 36 1983: 40 1984: 41 1985: 29 1986: 25 1987: 23 1988: 26 1989: 41 1990: 24 1991: 32 1992: 76 1993: 21 1994: 46 1995: 17 1996: 18 1997: 21 1998: 14 1999: 9 2000: 20 2001: 17 2002: 16 2003: 17 2004: 8 2005: 17 2006: 14 2007: 13 2008: 9 2009: 10 2010: 27 2011: 4 2012: 10 2013: 15 2014: 23 2015: 5 2016: 5 2017: 8 2018: 10 2019: 10 2020: 12 2021: 11 2022: 19 2023: 22 2024: 103 103 2025: 37 19731978198319881993199820032008201320182023

Earlier earthquakes of magnitude 5 or more within 50 miles, strongest first

USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.