The March 10, 1922 earthquake
M6.5Parkfield, California
A magnitude 6.5 earthquake, centred in San Luis Obispo County. The 24th strongest in California’s record since 1900, and the strongest within 50 miles in the catalogue, which runs from 1900. 1 aftershock of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 6.5
- surface-wave magnitude (ms)
- Depth
- —
- Not recorded
- Local time
- Friday, March 10, 1922
- 03:21 PST; 11:21 UTC
- In California’s record
- 24th
- strongest of 97,065 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event ushis675 (“1922 Parkfield, California Earthquake”). 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
5.0
Largest aftershock, Mar 16, 1922 · its page
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
- San Luis Obispo CountyCA · inside
- Monterey CountyCA · 3.4 mi
- Kings CountyCA · 3.4 mi
- Kern CountyCA · 4.1 mi
- Fresno CountyCA · 11.5 mi
- Tulare CountyCA · 40.0 mi
- San Benito CountyCA · 40.5 mi
- Santa Barbara CountyCA · 44.9 mi
Cities, largest first
- San Luis ObispoCA · 40.9 mi
- Paso RoblesCA · 24.0 mi
- AtascaderoCA · 30.6 mi
- LemooreCA · 45.4 mi
- CorcoranCA · 44.9 mi
- Arroyo GrandeCA · 47.2 mi
- CoalingaCA · 26.9 mi
- AvenalCA · 20.8 mi
- Grover BeachCA · 48.2 mi
- Morro BayCA · 43.7 mi
Earthquakes around the epicentre
1,667 earthquakes of magnitude 3 or more within 50 miles of this epicentre since 1973.
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.