I study environmental problems from a geologic perspective with emphasis on natural hazards. The primary objective of my research program is to identify active faults and to quantify their potential for generating large earthquakes by discovering their history of earthquake production over geologic time intervals. The record of previous large earthquakes on active faults is one of the best indicators of future earthquake activity. The results of my research on earthquake occurrence patterns are applied for earthquake forecasting, land-use planning, building design, risk assessment, disaster preparedness planning, and public education about the earthquake threat.