Scientists have raised alarms over the possibility of a towering 1,000-foot “mega tsunami” that could devastate vast portions of the United States’ West Coast. The threat stems from the Cascadia subduction zone, an active fault line stretching from northern Vancouver Island to Cape Mendocino in California. According to a recent study by geoscientists at Virginia Tech, published in the Proceedings of the National Academy of Sciences, there is an estimated 15 per cent chance of a magnitude 8.0 earthquake striking the region within the next 50 years.
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Should such an earthquake occur, it could trigger catastrophic consequences, including the potential submersion of land by up to 6.5 feet. Cities such as Seattle and Portland face particularly heightened risk. Unlike typical tsunamis, which generate waves of a few feet, mega-tsunamis can create walls of water hundreds—if not thousands—of feet high. The scientists noted that such an event would unfold within minutes, offering virtually no time for adaptation or evacuation.
Lead author of the study, Assistant Professor Tina Dura, highlighted that the potential expansion of coastal floodplains following such an event has not been adequately accounted for in existing planning. This oversight could delay recovery efforts and severely impact future land use along affected coastlines. The research suggests the most significant impacts would likely be felt across southern Washington, northern Oregon, and northern California.
Though Alaska and Hawaii lie farther from the fault line, they too remain vulnerable due to their seismic and volcanic characteristics. Notably, there has been no major seismic event recorded in the Cascadia subduction zone since the year 1700. This long period of inactivity, researchers suggest, should not be mistaken for safety, but rather viewed as a sign of building geological pressure.
