1993 Scotts Mills Earthquake

At 5:34 a.m. on March 25, 1993, the Scotts Mills earthquake rocked northwest Oregon and southeast Washington. The earthquake registered at a 5.6 magnitude, making it the largest earthquake in the Pacific Northwest since 1981. Near the epicenter, the earthquake generated shaking as high as VII on the Modified Mercalli Intensity scale. This means that very strong shaking could be felt by all, causing negligible damage in well-built structures but considerable damage to poorly built structures. The Scotts Mills earthquake caused over $28 million in total damage (in 1993 dollars).

The Scotts Mills earthquake was a crustal earthquake that occurred on the Mount Angel Fault Zone, about 54 miles south of Portland near the rural town of Scotts Mills. The shaking was felt widely in the Willamette Valley and the Portland metro area, and even as far away as Roseburg and Seattle. In Portland, some homes’ plaster and foundations even cracked. Closer to the epicenter, unreinforced masonry buildings suffered moderate damage, and one bridge was closed for several days.

Due to its timing and location, the Scotts Mills earthquake caused only minimal injuries and moderate damage. Unreinforced masonry buildings suffered the greatest impacts, including failed walls and topped gables. Molalla High School, a three-story unreinforced masonry building, lost its chimney and two gables. Two of its brick walls partially collapsed as well. The earthquake also damaged the State Capitol building, cracking its dome and shifting the pioneer statue on top. Additionally, the Highway 18 bridge over the Yamhill River was temporarily closed due to structural damage.

Otherwise, damage was mostly limited to broken windows and items that fell from shelves in homes and stores. No known surface deformation, liquefaction, landslides, or ground cracking occurred. The earthquake originated about 16 kilometers beneath the Earth’s surface. Had the earthquake happened later in the day during a normal school week, instead of early in the morning during spring break, the outcomes could have been much worse. This serendipitous timing may have saved lives at Molalla High School. Likewise, had the earthquake struck a more populated area instead of rural Marion County, casualties could have been much higher. Only minor injuries were reported, mostly related to broken glass or fallen objects. Nevertheless, the Scotts Mills earthquake served as a wake up call to many Oregonians that they were living in earthquake country.

This event serves as a reminder that being properly prepared for a destructive earthquake can save lives and reduce damage. Retrofitting older buildings and performing non-structural hazard mitigation can greatly reduce hazards to human life and property during an earthquake. Individuals should ensure they know what to do during and after an earthquake. If you feel shaking, Drop, Cover, and Hold On. Have an emergency kit prepared and accessible. Earthquakes like the one in Scotts Mills don’t have to be devastating; simple preparation steps can greatly reduce injuries, loss of life, and damage.

The PNSN did not have a web system going in 1993, but did produce a summary that was later put on our web system, which was started in 1995. There is a simple PNSN legacy web page for this earthquake.

For more information about how to prepare for an earthquake, visit this page: Preparedness.