Portable ground-penetrating radar

As part of his research, Phil Wernette (USGS Mendenhall Research Fellow) collects a 200-MHz ground-petetrating radar (GPR*) survey along the Lake Michigan coast (near Manistee, MI). There, the clay coastal bluffs are actively eroding. The GPR data will help Phil to better understand how variations in internal geology and hydrology drive differences in rates and processes of coastal bluff erosion at a variety of space and time scales. These GPR surveys can be utilized across a wide range of environments and can provide an important baseline of conditions, providing context for evaluating future coastal changes.

*The GPR system emits a tiny pulse of radar energy into the ground, and then records the strength and timing of any return signal reflected back to the receiver. Because different layers of sediment have different electrical conduction, they return very different signals. For example, dry sand layers atop wet sand layers produce a very strong reflection, whereas dry sand layers atop limestone will produce a weaker reflection. When the radar travels through uniform sediment with no variation, the signal will simply continue to travel until it dissipates or until the GPR control unit has stopped "listening" for the return signal. This system helps scientists to better visualize and map the layers of sediment and rock underground.