PORTLAND, Ore. (KOIN) — Friday’s 4.4 magnitude earthquake in Linn County was a reminder that, although rare, the Willamette Valley and surrounding areas are capable of producing some powerful quakes.
Settled uncomfortably close to the Cascadia subduction zone that spans Oregon, Washington and Northern California’s coastline, the Willamette Valley is susceptible to devastating 9.0 earthquakes caused by a subduction zone earthquake. A quake of this magnitude, which is believed to hit the Pacific Northwest every 190 to 1,200 years, would crumple the region’s current infrastructure, emergency officials warn, destroying bridges, waterlines and buildings.
However, with the last event occurring in 1700, scientists have never been able to record a Cascadia subduction zone event with modern instruments.
With modern equipment, Oregon State University seismology expert Andrew Meigs told KOIN 6 that scientists are much more prepared for recording earthquakes than they were 50 years ago.
“The regional coverage of seismometers has grown from five in 1969 to more than 300 today,” Meigs said.
While the USGS’s oldest earthquake records for Oregon date back to the late 1800s, these records may not represent the full list of regional earthquakes that occurred throughout this period of recorded history. However, the USGS earthquake catalog does offer interesting insight into Oregon and the Willamette Valley’s seismic history.
With that said, here are the four most powerful earthquakes ever recorded around the Willamette Valley:
McMinnville, Oregon — 5.0M
On April 2, 1896, A 5.0 magnitude earthquake rumbled near McMinnville. USGS says it was about 6.8 miles deep.
Portland, Oregon — 5.0M
Just four years before the McMinnville quake, another earthquake shook through the Portland urban area on February 4, 1892. It was reportedly just under 10 miles deep.
Bridgeton, Oregon — 5.2M
Fast-forward to the 1960s, when a quake hit roughly three miles east of Bridgeton, a Portland neighborhood. USGS reports the earthquake occurred on November 6, 1963, and was over 9 miles deep.
Scotts Mills, Oregon — 5.6M
The so-called “Spring Break Quake” of 1993, also known as the Scotts Mills earthquake, occurred on the morning of March 25. It was felt around the Pacific Northwest and was one of the largest earthquakes to ever be recorded in the Willamette Valley region.
It was reported to be more than 12 miles deep.