Crustal Structure of the Iran Region from In-Country and Ground-Truth Data; Conference paper

摘要

We are investigating the crustal and upper mantle structure of the Iran region using in-country data sets of seismic phase arrival times, supplemented by ground-truth data sets developed from our previous research efforts. Other data sets from global, regional, and national bulletins in the region are being integrated as well. The in-country data sets, covering approximately the last 10 years of seismicity in the region, are being carefully reviewed for quality control, selectively re-picked, and combined with ground truth and other data sets for careful relocation of all seismic sources with magnitudes of approximately 2.5 and larger. Using these relocated sources with well-characterized uncertainties and the associated phase readings for crustal and regional phases, we perform forward modeling and tomographic inversion, under the assumption of isotropic velocities, to study the velocity structure and variability of the crust and upper mantle in this region. The resulting models and datasets will provide a well-characterized baseline for more detailed studies in the future. We are continuing efforts to discover and develop new ground truth data sets in this region. We present some of the currently available data sets for this effort, along with preliminary tomographic inversion results based on them. We present a strategy for tomography based on ray-tracing in a region for which substantial variations in crustal thickness are expected, and using datasets that have different characteristics than those normally employed for this type of study. Through relative event relocation, clusters of events have very strong constraints on relative location, depth, and origin time. For each cluster, then, there will be only a single set of free parameters addressing uncertainty in location, depth, and origin time of the cluster's hypocentroid, rather than independent parameters for each event in the cluster.