Unique seismic datasets of extreme importance to the U.S. Air Forces mission to monitor underground nuclear testing may need to be discarded if the seismometer specifications, often called the response, are unknown. However, if these unique datasets are discarded, it could diminish mission capability. This project will develop a software toolbox that will recover the seismometer response for recorded seismic data. The toolbox will include (1) a database of known seismometer and digitizer responses, (2) methods for estimating response ¿transfer¿ functions between stations with and without known responses, (3) techniques for using synthetic seismograms for response validation, and (4) advanced methods for timing and polarity quality control. Commercial Applications and other Benefits as described by the awardee The toolbox would provide DOE nuclear-explosion-monitoring scientists with a valuable asset for characterizing datasets that can improve the Air Forces ability to detect, locate, and discriminate underground nuclear explosions. Future commercial applications would provide global and regional seismic network operators, including operators that monitor oil and gas fields, a sophisticated capability to continuously monitor the system response of their networks.