In Japan, seismic waves slower after rain, large earthquakes
Monday, March 5, 2012 - 04:30
in Earth & Climate
An earthquake is first detected by the abrupt side-to-side jolt of a passing primary wave. Lagging only slightly behind are shear waves, which radiate out from the earthquake's epicenter and are seen at the surface as a rolling wave of vertical motion. Also known as secondary or S waves, shear waves cause the lifting and twisting motions that are particularly effective at collapsing surface structures. With their capacity to cause damage, making sense of anything that can influence shear wave vertical velocities is important from both theoretical and engineering perspectives.