Seismic waves from light trucks moving over terrain

Seismic sensing is one sensor mode employed in US unattended ground sensor systems (UGS). Seismic sensors possess the advantage of beyond-line-of-sight sensing. They can detect ground vibrations generated by moving vehicles or personnel and they can be used to cue other sensors or possibly to classify or even identify targets. As a complement to field trials, our work has produced a simulation capability to support seismic UGS developments. We model ground vibrations from moving vehicles and generate synthetic seismic wavefield data over terrain of interest to US forces. Using supercomputers to simulate seismic wave propagation in large finite-difference time-domain simulations, our objective is to generate high fidelity data sets that provide new opportunities for understanding and exploiting signal features that may be unrecognizable in limited field trials. The method utilizes a vehicle-dynamics model to calculate the vehicle response to vehicle acceleration and movement over bumpy roads or terrain. It calculates forces transmitted to the ground; distributes these forces to grid points of a finite difference model; and simulates seismic waves propagating away from the vehicle. The current work focuses on light trucks moving toward and through a mountain pass and signature features associated with suspension and wheelbase characteristics. The results from two analyses show seismic waves propagating away from one and two trucks, respectively. We conclude that the wavefield data is realistic and suitable for virtual trials of seismic UGS.