Posted by Adesh Pandey

In recent years, distributed acoustic sensing (DAS) has emerged as a promising technology that uses fiber optic cable as a dense array of seismic sensors. Deploying DAS in urban areas for shallow seismic imaging not only provides a cost-effective solution as it has minimal maintenance cost and is potentially less intrusive when compared to traditional seismometer technology.

To further increase the speed and efficiency of shallow seismic data recording and thereby decrease acquisition costs, we are developing a towed land streamer that utilizes fiber-optic cable to acquire seismic data. The initial design consists of a fiber cable attached to trailer-mounted hose pipe and towed by a truck along the ground surface. The truck also houses the weight drop source. The weight of the hose assists with improving sufficient ground-fiber coupling. It also shields the fiber from environmental disturbances such as wind.

Our initial field tests and analysis of the recorded waveforms suggest superior results for our design when compared with simultaneously acquired geophone data. When compared to geophone deployments, the fiber data provides high temporal-spatial resolution seismic waveforms with much lower effort and hardware requirements. Preliminary multichannel analysis of surface waves (MASW) on DAS land streamer data opens the possibility of time-lapse imaging of shear-wave velocity (V_S) structures. When fully operational, this new acquisition system should be faster and less expensive for a wide variety of engineering and environmental applications.

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