The earthquake that rocked Nepal last week was caused by a thrust along the impact zone, where the India Plate is grinding underneath the tectonic plate that most of Europe and Asia sits on, at roughly 45 millimeters per year. Today it’s well known that earthquakes occur along plate boundaries, but the theory of plate tectonics—which encompasses the idea the Earth’s crust is broken up into chunks that slide across the planet’s inner mantle—has only been widely accepted since the middle of the 20th century. Before that, inhabitants of seismically active areas came up with surprisingly consistent metaphors to explain Earth-shaking events: usually giant, wriggling underground creatures.
A 17th-century explanation of earthquakes and tsunamis from Japan laid the blame with dragons. The island nation was thought to rest directly on top of an underground serpent, kept in check by a distractible deity—earthquakes resulted whenever the god shirked his duties to keep the great animal pinned down. Over time, a 2007 paper from the Geological Society on folklore and earthquakes explains, the mythical figure gradually morphed from a dragon into Namazu—a giant catfish.
Similarly, Sumatran legends speak of subterranean water serpents shaking the Earth, according to the 2007 paper, and these myths of underground catfish and serpents are reminiscent of folklore from the seismically shaky Pacific Northwest. There, instead of massive catfish or serpents struggling beneath the surface of the Earth, giant whales trapped inland were thought to be writhing their way back to sea.
These myths and stories can actually provide scientists with insights into the history of earthquakes in seismically active regions: the Cascadian earthquake of 1700—a massive, magnitude 9 earthquake—was dated using non-geological historical documents from Japan and oral Native American stories from the Pacific Northwest.