The Anthropogenic Ambient Noise Field: Tracking Cars, Trains and Planes Seismically

The seismic noise field is rich in information about the environment and its sources. We demonstrate how ambient seismic data can be used to reveal a metro schedule, monitor vehicle density on a highway, and track departing and landing aircraft. The data comes from a geophone array that covered over 70km2 of Long Beach (CA), including metro tracks, a section of the I-405 highway, and the Long Beach airport. Anthropogenic features are extracted by computing a space-time representation of seismic power and applying a filter in that domain that enhances signatures of moving sources. We discuss the potential and challenges of using seismic networks as a tool for small scale environmental monitoring as well as traffic monitoring.