Earthquake Data in Structural Modeling

William J. Sercombe, Dr. H. W. Zhou

Focal Mechanism Solutions for recorded earthquakes offer an opportunity to improve structural models based on the principles of uniformitarianism. A review of a worldwide data set indicates that deformed belts are very complex and probably have been so in the past. The complexity involves the recognition of a large component of strike and oblique slip as well as oblique extension in belts typically referred to as "thrust" belts. The active compressional deformed belts of the Himalayas (Pakistan, Burma, India), Papau New Guinea, the Andes, New Zealand, Turkey, Greece and Taiwan all show a very heterogeneous mixture of structural styles. These deformed belts are dominated by components of oblique or strike slip. A series of pure "thrust" belt signatures from low angle plana strain, derived by focal mechanism solutions, is typically non-existent along the length of modern deformed belts.

Active subduction zones also display a heterogeneous set of structural styles. The data sets question the validity of generalized two dimensional conventional cross sections that typically illustrate subduction zones. Arcs, such as the Hellenic Arc are very heterogeneous and shallow. Extensional systems such as the Calabrian Arc reveal their pull apart bounding fault trajectories through earthquakes.

Earthquake data should be integrated into structural models and interpretations in general, especially in seismically active areas such as the Tethyan and Pacific rim basins.

Another line of earthquake information is the velocity structures as inferred from travel times of seismic arrivals. Such information is obtained from seismic tomography, and is now available in many regions.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995