USGS Home
Contact USGS
Search USGS

 Home  Resources  Research  Publications  About  Contact Us  Groundwater Information

Fractured Granite Block Experiment

This experiment was conducted during December 1996.  The granite block was quarried from a feldspathic granite formation in Connecticut.  The block of rock measures about 2 m in length, 1 m in width, and 1.5 m in height.  The artificially induced fracture is roughly parallel to and is located roughly 80 cm from the top surface of the block.  The GPR surveys were conducted with the Geophysical Survey Systems, Inc., SIR-10A+ system with the 500 MHz transceiver antennas, and with the Mala Geoscience Ramac system with 400 MHz transmitter and receiver antennas.*  Twenty-nine traces were collected; one every 5 cm along the top surface of the rock.   The fracture contained about 14 Liters (L) of water when it was saturated.

Animation of GPR data collected while water was draining out of a horizontal fracture through the center of the granite block.  Download Animated GIF File (500 KB).  (NB:  This file may take some time to download, as it is downloading successive frames may display at irregular intervals; once the file is downloaded in its entirety the frames will display smoothly.)

Preliminary experiment results showing the amplitude of a 400 MHz transmitted radar pulse. The fracture was filled with different liquids. The transmitter was held in a fixed position on the underside of the rock while the receiver occupied different stations across the upper surface of the rock.