Global Surface Wave Telegraphy Using Seismic Hum.

The article is a report on global surface wave telegraphy using seismic hum. Earth's seismic hum signals, which are background free oscillations, are continuously excited by the ocean and atmosphere. The authors used cross-correlation (CC) analysis of hum signals that showed background Rayleigh waves which were propagated globally. Topics include how the waves open the possibility for global surface wave tomography without references to earthquakes.