The April 25, 1957 earthquake
M5.0near Salton City, CA
A magnitude 5.0 earthquake 3.7 miles deep, centred in Imperial County. The 432nd strongest in California’s record since 1900, and the strongest within 50 miles since a magnitude 5.2 on April 25, 1957. 1 aftershock of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 5.0
- local magnitude (ml)
- Depth
- 3.7 mi
- 6.0 km below the surface
- Local time
- Thursday, April 25, 1957
- 14:24 PST; 22:24 UTC
- In California’s record
- 432nd
- strongest of 97,065 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event ci3295973 (“11km SW of Salton City, CA”). 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.
1
Aftershocks in 30 days
4.3
Largest aftershock, Apr 26, 1957
1
On the first day
1
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 · 10.7 mi
Cities, largest first
- IndioCA · 37.1 mi
- Palm DesertCA · 40.5 mi
- Cathedral CityCA · 49.2 mi
- CoachellaCA · 33.0 mi
- Palm SpringsCA · 49.7 mi
- El CentroCA · 40.6 mi
- La QuintaCA · 32.2 mi
- CalexicoCA · 48.4 mi
- BrawleyCA · 33.5 mi
- ImperialCA · 37.5 mi
- Rancho MirageCA · 44.0 mi
Earthquakes around the epicentre
2,932 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
- May 18, 1940M6.9
- October 21, 1942M6.6
- March 19, 1954M6.4
- April 18, 1906M6.3
- June 22, 1915M6.0
- March 25, 1937M6.0
- June 22, 1915M5.9
- August 15, 1945M5.8
- September 29, 1916M5.7
- October 21, 1942M5.6
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.