Earth's Background Free Oscillations

• DOI: 10.1126/science.279.5359.2089
• Publication Date: 2002-07-27T09:37:56Z
• Authors: Naoki Suda; Kazunari Nawa; Yoshio Fukao
• Keywords: Gravimeter; Transient (computer programming)

Earth's free oscillations were considered to be transient phenomena occurring after large earthquakes. An analysis of records the IDA (International Deployment Accelerometers) gravimeter network shows that Earth is freely oscillating at an observable level even in seismically inactive periods. The observed are fundamental spheroidal modes frequencies between 2 and 7 millihertz. Numerical modeling indicates these incessant excitations cannot explained by stacked effects a number small "background" represent some unknown dynamic process Earth.