The May 28, 1981 earthquake
M5.0near Packwood, Washington
A magnitude 5.0 earthquake 1.3 miles deep, centred in Yakima County. The 25th strongest in Washington’s record since 1900, and the strongest within 50 miles since a magnitude 5.2 on February 13, 1981. 1 aftershock of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 5.0
- duration magnitude (md)
- Depth
- 1.3 mi
- 2.1 km below the surface
- Local time
- Thursday, May 28, 1981
- 02:10 PDT; 09:10 UTC
- In Washington’s record
- 25th
- strongest of 5,002 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event uw10106318 (“23 km ESE of Packwood, Washington”). 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
2.9
Largest aftershock, May 29, 1981
0
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
- Yakima CountyWA · inside
- Lewis CountyWA · 1.9 mi
- Skamania CountyWA · 11.2 mi
- Pierce CountyWA · 18.1 mi
- Kittitas CountyWA · 31.8 mi
- Klickitat CountyWA · 34.8 mi
- King CountyWA · 38.7 mi
- Cowlitz CountyWA · 41.4 mi
- Thurston CountyWA · 41.7 mi
Cities, largest first
- YakimaWA · 40.4 mi
Earthquakes around the epicentre
1,293 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, 1980M5.7
- April 14, 1980M5.2
- February 13, 1981M5.2
- September 17, 1961M5.1
- April 8, 1980M5.1
- April 7, 1980M5.1
- April 5, 1980M5.1
- April 3, 1980M5.1
- April 20, 1980M5.1
- April 3, 1980M5.0
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.