9725140 Villasenor This research is a continuation of a cooperative effort between the Colorado School of Mines and the U.S. Geological Survey to systematically relocate historical seismicity based on travel-time information compiled in several catalogs of global seismicity. A final product from this project, a consistent global earthquake catalog covering the 20th Century, will triple the length of the current earthquake data bases. Earthquakes are relocated using a new location algorithm that dynamically re-identifies earthquake phases based on the probability density function of each phase's arrival time derived from modern observations. This research is a component of the National Earthquake Hazard Reduction Program. ***
