Cascadia Megathrust: The Clues It Left Behind When the Cascadia Megathrust earthquake struck on January 26, 1700, there were no local written records, but the landscape kept its own evidence. Along the Pacific Northwest coast, scientists have found “ghost forests,” where trees were suddenly killed as the land dropped and saltwater flooded in. In nearby marshes and soils, unusual sand layers mark where tsunami waves pushed far inland. Tree rings, soil layers, and buried shorelines all point to th