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A new study indicates that Oregon and coastal regions may be at significant risk for a major earthquake along the Cascadia Subduction Zone. This could lead to severe subsidence and flooding affecting over 22,000 residents. With a 15% chance of a magnitude 8 or greater quake in the next 50 years, crucial infrastructure and local communities will be heavily impacted. The potential danger is intensified by climate change and rising sea levels, necessitating urgent preparedness and mitigation strategies.

Oregon is facing a significant threat from a potential major earthquake along the Cascadia Subduction Zone, according to a recent study. This 600-mile long fault line located off the Pacific Coast is known for its seismic activity, and the new research outlines alarming consequences for coastal regions spanning from Northern California to Vancouver, Canada.

The study, published in the Proceedings of the National Academy of Sciences, warns that a major earthquake could lead to coastline subsidence, where certain areas may drop by more than 6 feet. Floodplain exposure could dramatically increase, affecting an estimated 22,000 residents in this vast region, compared to 8,000 currently. The number of at-risk structures could rise from 13,000 to 36,000, severely impacting local communities and infrastructure.

The potential flooding area is projected to expand by 116 square miles, an expanse comparable to the size of five Manhattans. Coastal towns like Seaside, Oregon, and Westport, Washington, could experience flooding roughly every century if a major quake occurs, reshaping these communities and their landscapes. The probability of an earthquake with a magnitude of 8.0 or greater happening within the next 50 years in the Cascadia Zone is estimated at 15%. For the southern section of the fault, this risk is believed to be even higher, reaching 37-42%.

In addition to land subsidence, scientists predict that such an earthquake would generate tsunami waves that could reach heights of 100 feet. The impact on existing infrastructure is expected to be severe, necessitating extensive reconstruction efforts for bridges, power lines, and vital services across affected regions. Past instances of large earthquakes in the Cascadia Subduction Zone provide historical context for the potential devastation. Evidence suggests that a major earthquake in 1700 resulted in severe coastal effects, including widespread destruction and subsidence that led to entire coastal forests and villages sinking into the ocean.

The implications of global sea level rise, which has already increased by approximately 8 to 9 inches since 1880, are compounded by climate change. Projections indicate an additional rise of 10 to 12 inches by mid-century, exacerbating the flood risks following a significant seismic event. Current land uplift in some areas of the Pacific Northwest could be entirely offset by the subsidence caused by a major quake, leaving many coastal communities uninhabitable in the long term.

The findings underscore the urgent need for preparedness in coastal localities. Flood risks do not only threaten residential areas but extend to critical infrastructure, which includes highways, airports, and wastewater treatment plants. Addressing these risks will require proactive measures and investments in mitigation strategies to protect vulnerable populations and ensure the resilience of coastal communities in the face of impending seismic threats.

Oregon Faces Major Earthquake Threat from Cascadia Subduction Zone

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Author: HERE Mission Viejo