The dominance of coastal microseisms in the Indian Ocean

Abstract

Strong microseisms in the Indian Ocean are generally attributed to the intense Southern Ocean processes. This conventional view, however, undermines the role of potential coastal reflections emanating from the adjoining landmasses. Here, we use an array of ocean bottom seismometers to investigate the role of coastal over Southern Ocean processes as triggering mechanisms for microseisms in the Indian Ocean. We apply polarization, power spectral density, correlation analysis along with numerical wave modelling and attenuation analysis to characterise microseisms and their potential sources. Contrary to the prevailing views, coastal reflections appear to dominate the strongest deep Southern Ocean seismic noise in the Indian Ocean. We attribute such anomalous behaviour to the propagation path effects. Interestingly, the strongest secondary microseisms are generated during the simultaneous development of cyclones in the opposite hemispheres. These findings have vital implications for the way we characterize and quantify the seismic noise in the closed ocean systems.