The first seismometers capable of measuring ground vibrations with periods of several seconds were installed in the early 20th century. Since then, the devices have recorded a continuous seismic hum, called "ocean microseisms." This hum is not the result of tectonic forces, but rather the response of the solid Earth to ocean wave-wave interactions, which have an annual global cumulative seismic energy comparable to that from earthquakes. Long considered noise by seismologists, ocean microseisms haverecently been found to be a useful resource for the interdisciplinary study of our planet. They provide a record of the state of the oceans since the early 20th century and are a passive seismic source for probing the geological structure of Earth's upper crust (0 to 20 km). Origins, applications, and future studies of ocean microseisms were discussed at the Fall 2004 meeting of the American Geophysical Union (7).
展开▼
