The March 25, 1993 earthquake
M5.6near Scotts Mills, Oregon
A magnitude 5.6 earthquake 12.2 miles deep, centred in Clackamas County. The 4th strongest in Oregon’s record since 1900, and the strongest within 50 miles in the catalogue, which runs from 1900. 8 aftershocks of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 5.6
- duration magnitude (md)
- Depth
- 12.2 mi
- 19.6 km below the surface
- Local time
- Thursday, March 25, 1993
- 05:34 PST; 13:34 UTC
- In Oregon’s record
- 4th
- strongest of 861 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event uw10306313 (“4 km E of Scotts Mills, Oregon”). 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.
8
Aftershocks in 30 days
3.2
Largest aftershock, Mar 25, 1993
5
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.
Counties and cities within 50 miles
Distance from the epicentre to each county boundary (zero when inside) and to each city centre.
Counties
- Clackamas CountyOR · inside
- Marion CountyOR · 1.2 mi
- Linn CountyOR · 17.0 mi
- Yamhill CountyOR · 19.5 mi
- Polk CountyOR · 21.4 mi
- Washington CountyOR · 21.6 mi
- Multnomah CountyOR · 27.5 mi
- Benton CountyOR · 34.3 mi
- Clark CountyWA · 37.4 mi
- Wasco CountyOR · 39.2 mi
- Skamania CountyWA · 39.5 mi
- Jefferson CountyOR · 41.8 mi
- Tillamook CountyOR · 43.6 mi
- Hood River CountyOR · 46.9 mi
- Columbia CountyOR · 48.5 mi
Earthquakes around the epicentre
46 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
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.