The February 25, 1930 earthquake
M5.0near Brawley, California
A magnitude 5.0 earthquake, centred in Imperial County. The 451st strongest in California’s record since 1900, and the strongest within 50 miles since a magnitude 5.0 on October 2, 1928. 2 aftershocks of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 5.0
- local magnitude (ml)
- Depth
- —
- Not recorded
- Local time
- Tuesday, February 25, 1930
- 18:30 PST; 02:30 UTC on Feb 26, 1930
- In California’s record
- 451st
- strongest of 97,065 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event ushis837 (“3 km NE of Brawley, California”). The USGS event page carries the ShakeMap, felt reports and the official summary.
Aftershocks
Earthquakes of magnitude 2.5 or more within 20 miles of the epicentre in the 30 days after.
2
Aftershocks in 30 days
4.5
Largest aftershock, Mar 1, 1930
0
On the first day
0
In the 7 days before
- The search radius is the surface rupture length expected for an earthquake of this magnitude (Wells and Coppersmith, 1994), at least 20 and at most 600 miles, so a great earthquake's sequence is counted along its whole fault.
- Before the modern seismic networks of the 1970s many small aftershocks went unrecorded, so early sequences read short.
Counties and cities within 50 miles
Distance from the epicentre to each county boundary (zero when inside) and to each city centre.
Counties
- Imperial CountyCA · inside
- San Diego CountyCA · 34.1 mi
- La Paz CountyAZ · 46.3 mi
- Yuma CountyAZ · 48.0 mi
Earthquakes around the epicentre
3,198 earthquakes of magnitude 3 or more within 50 miles of this epicentre since 1973.
Earlier earthquakes of magnitude 5 or more within 50 miles, strongest first
- April 18, 1906M6.3
- June 22, 1915M6.0
- January 1, 1927M6.0
- June 22, 1915M5.9
- November 7, 1923M5.7
- September 29, 1916M5.7
- May 27, 1917M5.5
- April 30, 1918M5.0
- November 5, 1923M5.0
- October 2, 1928M5.0
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.