By Sid Perkins
An oceanographic survey off the northern coast of Puerto Rico has found remnants of many past underwater landslides, a handful of which were large enough to have caused deadly tsunamis.
Although most tsunamis are caused by earthquakes, a small percentage of the destructive waves are triggered by seafloor slumping (SN: 3/6/04, p. 152: Killer Waves). Sonar revealed the landslide remnants off Puerto Rico, says Uri S. ten Brink, a geophysicist with the U.S. Geological Survey in Woods Hole, Mass. He and his colleagues report their findings in the June 16 Geophysical Research Letters.