Kiholo Bay Aftershocks - Thumping for Science
Detailed Description
George E. Brown, Jr. Network for Earthquake Engineering Simulation mobile shaker "Thumper," a modified Ford F650 truck equipped with hydraulic pumps and shakers. Thumper operates at frequencies between 17 and 225 cycles per second, and is capable of generating a maximum force of 6000 pounds. Photo from http://nees.utexas.edu/Equipment-Thumper.shtml