Earth Vibrations

摘要

Intense cyclonic storm systems generate strong ocean-surface winds that transfer atmospheric energy into ocean gravity waves. Some of the ocean wave energy couples to the solid earth, causing what seismologists have long considered as ambient "noise," because it interferes with the study of earthquake signals measured by seismometers. However, rising ambient noise levels imply increasing oceanic storminess (7), which is linked to climate change. In this context, the roles are reversed, with earthquakes being the noise that needs to be excluded from the climate-related signals. Studies of long-term seismic records suggest that wave-generated ambient noise is increasing globally (2).