Air-Powered Impulsive Shear-Wave Source With Repeatable Signals

About the Development

Researchers at the U.S. Geological Survey (USGS) have designed an instrument that can be used by engineers, consultants, municipalities, and in other geophysical applications to help provide information needed to monitor and plan for earthquakes. The air-powered impulsive shear-wave source is specifically used in downhole velocity logging experiments. The velocities measured by the instrument are used as input parameters for making earthquake zone maps. The USGS instrument is an improved design that generates cleaner signals than prior technology.

When in use, the instrument is firmly held on the ground surface by the front-end weight of a truck. Two hammers, attached to the ends of an air-cylinder piston rod, slide on low-friction tracks. These hammers alternately impact anvils clamped between two aluminum channels. The resulting traction exerted on the ground surface by the lower channel produces a repeatable wave field having a large shear-to-compression amplitude ratio in directions perpendicular to and bisecting the channel. Signals generated by the device are highly repeatable.

Test Results

Field tests of the instrument have demonstrated that it offers applications for measuring shear-wave arrival times and amplitudes over extended distances.

Partnership Opportunity

The USGS is interested in making the device commercially available. It is seeking business partners to refine and test the instrument and to market it.

For More Information

Additional information about the shear-wave generator and partnering with the USGS on this project may be obtained by contacting:

Hsi-Ping Liu
U.S. Geological Survey
Western Earthquake Hazards Team
345 Middlefield Road, MS 977
Menlo Park, CA 94025
tel: (415) 329-5643
fax: (415) 329-5163
email: liu@usgs.gov