Abstract
Knowledge of the geometry and connectivity of seismogenic and active fault systems is a key to understanding on-going active tectonic processes and evaluating the risk of destructive earthquakes. Knowing the geometry of the deeper extensions of active faults in the seismogenic zone, contributes to estimating source parameters for scenario earthquakes, like fault geometry, co-seismic displacement, and the location of possible asperities. Together with monitoring seismicity and surface deformation, delineating the geometry of seismogenic faults allows us to construct quantitative models of crustal deformation. Seismic reflection profiling is a powerful tool to discern the deep geometry of faults. Since the Kobe earthquake of 1995, deep seismic profilings have been carried out across some active faults in the Japanese islands, such as the Ou Backbone Range in northern Honshu. Through these seismic experiments, using vibroseis trucks and explosive sources, the geometry of seismogenic and active fault systems is successfully obtained in spite of some difficulties due to rough topography, high attenuation and man-made noise. Deep seismic profiling has a great potential for the direct imaging deep crustal structures, including deep fault geometry.
