Microtremors, ocean waves, and other items

Ocean waves are known to be a dominant component of microtremors worldwide in the frequency band from 1 to 10 Hz (Peterson, 1993). Recently, Lambert et al. (2009) claimed that spectral anomalies in microtremors can detect underlying hydrocarbon reservoirs. However, Hanssen and Bussat (2008) and Ali et al. (2010) got experimental results leading to opposite conclusions, because of the lack of signal repeatability and the correlation between spectral anomalies and near-surface topography. This paper expands the related work of Nieto et al. (2011) with new data from the OGS Seismological Network (OASIS Working Group, 2011) and the Marine Environmental Monitoring Network, showing that geological structures and active faults may be locally dominant factors too.