Recorded Oregon earthquake events date back to 1841, since this time there has been more than 6,000 earthquakes in Oregon, most with a magnitude below three. Portland and its surrounding region is potentially the most seismically active area within Oregon.
The Portland metropolitan region has encountered seventeen earthquakes of an estimated magnitude of four and greater, with major earthquakes in 1877 (magnitude 5.3), 1962 (magnitude 5.2), and 1993 (magnitude 5.6). Records also indicate that earthquakes in the Puget Sound Region, such as the 1949 magnitude 7.1 event near Olympia, WA, and the 1965 magnitude 6.5 event located between Seattle and Tacoma, can cause damage in Portland.
Here is a list of notable Oregon earthquake events:
February 28, 2001: Magnitude 6.8 – The Nisqually earthquake caused high-rise office buildings in Portland to sway for 20 to 30 seconds and some exterior cosmetic cracks of the Public Safety Building in Hillsboro. 3
March 25, 1993: Magnitude 5.6 – The earthquake near Scotts Mills, Oregon, 32 miles from Portland, was a shallow crustal earthquake recorded at magnitude 5.6. This earthquake caused damage mostly within a radius of about 25 miles, primarily in the communities of Molalla, Woodburn, Newberg, and McMinnville. While there were no reported injuries, structural damages did occur.
March 7, 1963: Magnitude 4.6 – In Salem a quake measuring 4.6 on the Richter scale shook Polk County. Despite the low magnitude of the quake, damage still occurred (especially to older masonry buildings).
November 5, 1962: Magnitude 5.2 – In the Vancouver, Washington area three and a half weeks after a devastating Columbus Day Storm, an earthquake measured approximately 5.2 on the Richter scale and shook the Portland area. It was the largest quake to be generated by a fault under Portland and Vancouver. 4
April 18, 1961: Magnitude 4.6 – A quake in Albany, Oregon caused little damage to the county, but startled many residents. The quake was centered just south of Salem, and registered 4.6 on the Richter scale.
April 13, 1949: Magnitude 7.1 – Polk county residents felt an earthquake that was centered near Olympia, Washington. Three earthquakes have affected southern Oregon since 1870. The first earthquake of note is the largest recorded earthquake in Oregon history. It occurred on November 23, 1873 at the California border on the coast and had a magnitude of 6.75. Damage was reported along the coast and in Josephine and Jackson Counties.
April 14, 1920: An earthquake of unrecorded magnitude was centered around Crater Lake.
September 20, 1993: Magnitude 5.0 and 6.0 – There were two initial quakes that were followed by a number of aftershocks, the largest being a 5.1 quake in December of 1993. 4
Bott, Jacqueline D.J. and Wong, Ivan G. Historical earthquakes in and around Portland, Oregon. September 1993). Oregon Geology 55 (5). 116.
“Local damage from quake centered near Seattle.” March 1, 2000. Hillsboro
Hill, Richard. “Geo Watch Warning Quake Shook Portland 40 Years Ago.” The Oregonian. October 30, 2002. Josephine County Emergency Services Plan; August 2004 page 4