The Porous Media group at NCPA, currently led by Dr. Craig Hickey, studies the propagation of sound in heterogeneous media such as soil and sand and the interaction between atmospheric born sound and the ground. Porous media propagation is an important factor in a wide range of problems. This group has studied the use of acoustic waves to detect buried objects and structures such unexploded ordinances, IEDs, and tunnels. These methods often use laser based detection schemes for measuring the vibration of the ground. These laser techniques have been expanded to study explosive residue detection from a safe distance and the use of multiple laser beams to acquire vibration data over an array of points on the surface.
The Porous Media group has also studied the use of acoustics to non-destructively determine the structural health of earthen levees and dams, measure the sediment payload carried by rivers and streams, accurately count fish stock in real time, and characterize Rayleigh (surface) wave propagation in a variety of soil types.