Until recently, scientists believed that underwater landslides generated just three percent of tsunamis around the globe. But a new study published in Nature Geoscience indicates that this is not the case.
The January earthquake that devastated Haiti birthed tsunami waves that grew up to three meters. Researchers have isolated the cause as sediment at the shore that snapped off and skidded along the seafloor: an underwater landslide that displaced the water above
The study suggests that the potential for tsunamis is higher than generally predicted in cities such as Kingston, Istanbul and Los Angeles, which lie close to strike-slip faults.
Tsunamis are primarily produced at subduction zones, where an oceanic tectonic plate slides under a continental plate, resulting in an earthquake and upward forcing of water. At strike-slip faults plates slide past each other. This action does not force the ocean upward. However, as evidenced in Haiti, the sliding of these plates can create underwater landslides.
“You do not need a large earthquake to trigger a large tsunami,” said lead author Matt Hornbach, from the University of Texas at Austin’s Institute for Geophysics. “A moderate earthquake on a strike-slip fault can still be cause for alarm.”