Those findings are the tip of the iceberg, according to a just released study by the Fralin Life Sciences Institute’s Tina Dura. It paints a frightening picture of the damage a big quake would bring to the Pacific Northwest. The study’s projections suggest that an earthquake occurring today could put another 14,350 people inside the post-earthquake floodplain. Nationally, this drastic increase in flood exposure will more than double our current at-risk population. It will directly affect their critical infrastructure, damaging 22,500 structures and 777 miles of roadway.
The results shed light on where communities are most at-risk from flooding. This risk first arises following a large earthquake on the Cascadia subduction zone. The Pacific Plate collides with an adjacent plate in this complicated tectonic subduction zone. The fault has remained remarkably silent since the last great quake hit on January 26, 1700. If a major seismic event were to strike, the damages would be catastrophic. It would take an enormous toll on communities, impacting five airports and eighteen critical facilities such as public schools, hospitals, police stations and fire stations. Eight wastewater treatment plants and one electric substation are at high risk. In addition to them, 57 possible sources of contaminants face danger.
Historical Context and Geological Insights
Authors of the study allude to historical examples, particularly the 1960 Chile earthquake, which caused extensive land subsidence. This event submerged a pine forest and farms, transforming them into tidal marshes and forcing coastal residents to abandon their homes. Dura’s research shows that similar impacts would be felt after a future major earthquake on the Cascadia subduction zone running through the Pacific Northwest.
The Cascadia subduction zone has produced eleven megathrust earthquakes in the last 3000 years at an average recurrence interval of 200 to 800 years. The last big tremor dropped up to 6.5 feet of earth under much of the coast, an area home to Big Sur and other natural beauty. Climate change is driving sea levels higher at a projected long-term rate of up to three feet by 2100. Yet this trend heightens the vulnerability of coastal communities to compounded risk.
“The expansion of the coastal floodplain following a Cascadia subduction zone earthquake has not been previously quantified, and the impacts to land use could significantly increase the timeline to recovery.” – Tina Dura
Dura wants people to know that the area’s sparse, rugged geographical features make recovery even tougher. Thousands of communities live inside estuaries that are extremely vulnerable to subsidence.
Immediate and Long-term Implications
The direct aftermath of a major earthquake would shut down all those services and would likely take years to recover from. Dura cautions that damaged infrastructure could prevent first responders from responding in the aftermath of a disaster.
“Today, and more so in 2100 as background sea levels rise, the immediate effect of earthquake-driven subsidence will be a delay in response and recovery from the earthquake due to compromised assets. Long-term effects could render many coastal communities uninhabitable.” – Tina Dura
As neighborhoods continue to deal with the fallout from these issues, they’ve felt an environmental impact. The continued loss of intertidal wetlands would be a detriment to ecosystem services like water filtration, habitats for commercial and recreational fisheries and migratory shorebirds, among others.
“The loss of intertidal wetlands directly impacts ecosystem services such as water filtration, habitat for fisheries and shorebirds, and carbon storage capacity.” – Tina Dura
Dura thinks that this research provides crucial lessons learned for the Pacific Northwest. Implications for other tectonically active regions This same concern is not just limited to the U.S.
Broader Implications for Coastal Communities
Given the global prevalence of subduction zones, Dura’s findings underscore the importance of preparedness and proactive measures in mitigating risks associated with seismic activity. The stakes go much further than just avoiding today’s baseline flood risk; this involves real leadership on sustainability and community resilience.
“Given the global prevalence of subduction zones, these insights hold relevance beyond Cascadia, informing hazard assessments and mitigation strategies for tectonically active regions worldwide.” – Tina Dura
Local governments and residents are busy crafting their local plans of action informed by these results. There’s no question that having an appreciation for geological risks is key to the goal of saving lives and property.