The August 20, 1993 earthquake
M5.0near Joshua Tree, California
A magnitude 5.0 earthquake 5.1 miles deep, centred in Riverside County. The 451st strongest in California’s record since 1900, and the strongest within 50 miles since a magnitude 5.3 on December 3, 1992. 9 aftershocks of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 5.0
- local magnitude (ml)
- Depth
- 5.1 mi
- 8.2 km below the surface
- Local time
- Friday, August 20, 1993
- 18:46 PDT; 01:46 UTC on Aug 21, 1993
- In California’s record
- 451st
- strongest of 97,065 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event ci3118441 (“12km S of Joshua Tree, 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.
9
Aftershocks in 30 days
3.5
Largest aftershock, Sep 7, 1993
2
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.
Counties and cities within 50 miles
Distance from the epicentre to each county boundary (zero when inside) and to each city centre.
Counties
- Riverside CountyCA · inside
- San Bernardino CountyCA · 34.8 mi
- San Diego CountyCA · 43.8 mi
- Imperial CountyCA · 43.8 mi
Cities, largest first
- IndioCA · 21.1 mi
- HemetCA · 43.8 mi
- RedlandsCA · 48.7 mi
- BeaumontCA · 37.7 mi
- HighlandCA · 48.7 mi
- San JacintoCA · 41.8 mi
- YucaipaCA · 41.3 mi
- Palm DesertCA · 20.3 mi
- Cathedral CityCA · 15.7 mi
- CoachellaCA · 25.5 mi
- Palm SpringsCA · 20.0 mi
- La QuintaCA · 26.9 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
- June 28, 1992M7.3
- April 21, 1918M6.7
- June 28, 1992M6.3
- April 22, 1992M6.1
- March 25, 1937M6.0
- December 4, 1948M6.0
- July 8, 1986M6.0
- June 28, 1992M5.8
- June 28, 1992M5.7
- May 2, 1949M5.7
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.