Researchers from Ohio State University have shown that undersea landslides can trigger powerful tsunamis that threaten coastal communities in North America. The findings were detailed in Geophysical Research Letters, a respected scientific journal.
The team’s conclusions come from modeling the consequences of underwater rock and sediment failures within the Cascadia subduction zone, a seismic belt off the Oregon coast. This zone extends along North America’s Pacific coastline, from Vancouver Island in Canada down to Cape Mendocino in Northern California.
The specific event studied, known as Landslide 44-K or simply 44-K, involved large rock masses detaching from a height of about 1,200 meters and moving at a shallow incline of 13 degrees. The moving material then traveled roughly 10 kilometers along the seabed. Although seawater offered resistance, the landslide slid forward at speeds near 60 meters per second, creating a layered, deformed trail several hundred meters thick that stretched for many kilometers.
Scientists calculated that the 44-K slide would have produced a significant tsunami had the water been able to react in that moment. However, the exact timing of the event remains uncertain, and researchers cannot confirm that a tsunami followed this landslide in the historical record.
There are historical accounts suggesting similar coastal hazards. An earthquake in 1929 near the southeast of Newfoundland triggered an underwater landslide that moved at speeds between 15 and 30 meters per second. The displacement of rocks generated a powerful tsunami that devastated coastal settlements and severed underwater communication cables linking North America and Europe. Twenty-nine people lost their lives in that disaster.
One of the study’s co authors notes that undersea landslides can occur so rapidly that they threaten critical internet infrastructure laid on the ocean floor, create tsunamis, and even intensify their effects. The researchers emphasize that without better seafloor imaging technologies, both past landslides and future threats may go undetected.
A separate observation points out that off the coast of Japan a new island emerged following an underwater volcanic eruption, underscoring the dynamic and sometimes dramatic changes that can occur beneath the waves. At a time when coastal communities across Canada and the United States rely on reliable communications and safe shorelines, understanding these processes helps scientists better assess risk and improve early warning capabilities. In the broader context, this line of research supports ongoing efforts to monitor submarine landslides, refine sea level forecasts, and invest in geotechnical sensing that can protect critical coastal infrastructure and natural habitats.