Dominant source regions of the Earth's “hum” are coastal

Abstract

Hum beam power observations using the USArray EarthScope transportable array, combined with infragravity wave observations, show that the dominant source area of the Earth's hum over the 120–400 s period band during winter months is the Pacific coast of North America, with the western coast of Europe a secondary source region. Correlation of hum with model ocean wave heights indicates that the Pacific coast of Central America is an important hum source region when impacted by austral storm waves. Hum is excited by relatively local infragravity wave forcing as ocean swell propagates along coasts, with no indication of significant deep‐ocean hum generation.