Active tectonic studies in the United States, 1987–1990

The past four years of active tectonic studies have been characterized by a maturing of established techniques, increasing integration with related fields, the application of several powerful new techniques, and expansion into new regions. Active tectonic studies continue to be driven primarily by a need for geologic input into the assessment of earthquake hazards. This need has led to studies in regions of diverse geology and development of new techniques appropriate for those regions. Long‐established active tectonic techniques, applied to the highly active faults of California and the well‐preserved faults of the desert Southwest have not been as successfully applied to more diffuse, poorly exposed, or less active regions. There is a growing recognition that even in active regions much of the deformation is not manifested by large faults that break the surface of the earth, so new approaches to study these important active structures have been developed. The ongoing interdependence of seismic hazard evaluation and active tectonic studies has led to greater synthesis and comparison of results from different fields and the development of new techniques to integrate and test conclusions derived from related fields.