This grant, made through the Major Research Instrumentation (MRI) Program, in combination with funds from the Earth Sciences Instrumentation and Facilities Program, provides partial support for the acquisition of a pool of 400 lightweight portable seismographs, associated geophones, shipping cases, field computers, GPS clocks, and frequency counters for active source seismic experiments aimed at tomographically imaging the structure of the Earth's continental lithosphere. The instruments to be acquired by the University of Texas at El Paso (UTEP) were developed by a private company, Refraction Technologies (RefTek), in collaboration with personnel from UTEP, Rice University and the University of Texas at Dallas. The result has been the RefTek-125, a 2-3 lb. Instrument that operates on 2 D-cell batteries for up to two days with on board memory capable of 12 hours of continuous recording at 2 ms intervals or 48 hours at 8 ms. They are single channel instruments which are primarily suited for high frequency active source seismic experiments. The lightweight of the RefTek-125 significantly reduces shipping costs, allowing field deployment of greater numbers of instruments and to more remote locations than have been economically or logistically feasible with the older IRIS-Program for Array Seismic Studies of the Continental Lithosphere (PASSCAL) pool of community accessible instruments. For high-resolution shallow subsurface imaging, these instruments will also allow very dense (ca. 1-10 m separations) array deployments for 3-D investigations that can feasibly be carried out with only a single field vehicle and for relatively low cost. In return for future operational and management support from IRIS, the RefTek-125 pool of instruments will ultimately be available to the broader seismological community through the IRIS-PASSCAL program. ***
