Efficient deployment of fiber-optic cable seismic sensors

We explore the options in deployment of fiber-optic cables as seismic sensors, a technology that has only become practical recently. Cables provide sensing capabilities along their lengths and thus provide a fundamentally different capability than the traditional point sensors. Furthermore, cables can have gradual curves, and this enables deployments to be fit precisely to sensing needs such as irregularities in the terrain. We discuss grid deployments and contrast them with curving deployments such as regular and irregular spirals. We discuss how to manage deployments over terrain with varying degrees of interest for monitoring. We then discuss some of the processing challenges in analyzing data where one dimension (distance) is much more precise than another (time of occurrence). Key concerns are in detecting changes in speed and direction, which can be tracked if processors hand off data to one another at known turn points such as road intersections. We discuss a bent-cable deployment that can facilitate such tracking. This paper appeared in the Proceedings of SPIE Defense, Security, and Sensing Conference, Vol. 7693, Orlando, Florida, April 2010.