| Summary: | Subsurface monitoring plays an important role in utilising subsurface resources and preventing geologic hazards. This thesis comprises dissemination of the research in using seismic methods for subsurface monitoring. Here I demonstrate various applications of ocean-bottom fibre-optic distributed acoustic sensing (DAS) technology to marine seismic exploration and subsurface monitoring using active and passive seismic sources. These include conventional marine seismic sources, whale vocalisations and subsurface shear-wave resonance. In addition, I develop a new time-lapse (4D) seismic method based on traveltime, called “4D seismic time-strain inversion,” to monitor the time-lapse changes in geophysical properties of the subsurface. This method can determine the subsurface changes without prior knowledge nor assumption about geomechanical properties in the field of interest. All the research work done in this thesis could contribute to the advancement of fibre-optic DAS and 4D seismic technologies for subsurface monitoring.
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