Regional Seismic Wave Propagation in the Middle East

摘要

Two manuscripts were written, the first 'Teleseismic evidence for a break-off slab beneath NE Iran Continental Collision Zone' discusses initial work with Iranian colleagues to examine the upper mantle structure beneath the NE Iran continental collision zone. The data for this study were recorded by 19 three component broad-band seismic stations operated from August 2006 to February 2008 along a profile from the center of the Iranian Plateau, near Yazd, to the northeastern part of Iran on the Turan plate just north of the Kopeh Dagh Mountains. To determine the upper mantle velocity structure, we tomographically inverted 4383 relative teleseismic P-wave arrival times. The results show three transitions between high and low velocity contrasts in the upper mantle below Central and NE Iran and confirms the previously known low velocity upper mantle beneath Central Iran. This low velocity upper mantle is confined to a distance approximately 200 km from northern border of the Urumieh-Dokhtar magmatic arc along the seismic profile. Our tomographic model also reveals a shallow low velocity anomaly above a deep high velocity anomaly between Ashkabad and Doruneh Faults, where the resolution and ray coverage are good. We find a transition zone in upper mantle under the Ashkabad Fault that we interpreted as the suture zone between Iran and the Turan platforms. The second manuscript 'A thick lithospheric keel beneath the Zagros fold-and-thrust belt and its possible influence on mantle flow beneath the Middle East' discusses the upper mantle heterogeneous structure beneath the Zagros fold-and-thrust belt in southwestern Iran. Data for this work consists of all publicly- available seismograms recorded in the area surrounding the Iranian Plateau which occurred between 1977 and 2009, as well as data from the broadband seismic network within Iran operated by the International Institute for Earthquake Engineering and Seismology (IIEES) in Tehran, a total of approximately 110,000 seismograms.