Accession Number : ADA519779


Title :   Ground Truth, Magnitude Calibration and Regional Phase Propagation and Detection in the Middle East and Horn of Africa


Descriptive Note : Conference paper


Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK


Personal Author(s) : Nyblade, Andrew A ; Brazier, Richard A ; Adams, Aubreya ; Park, Yungcheol ; Rodgers, Arthur J ; Al-Amri, Abdullah


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a519779.pdf


Report Date : Sep 2007


Pagination or Media Count : 11


Abstract : In this project, we are exploiting several seismic data sets to improve U.S. operational capabilities to monitor for low yield nuclear tests across the Middle East (including the Iranian Plateau, Zagros Mountains, Arabian Peninsula, Turkish Plateau, Gulf of Aqaba, Dead Sea Rift) and the Horn of Africa (including the northern part of the East African Rift, Afar Depression, southern Red Sea and Gulf of Aden). The data sets are being used to perform three related tasks. (1) We are determining moment tensors, moment magnitudes and source depths for regional events in the magnitude 3.0 to 6.0 range. (2) These events are being used to characterize high-frequency (0.5-16 Hz) regional phase attenuation and detection thresholds, especially from events in Iran recorded at stations across the Arabian Peninsula. (3) We are collecting location ground truth at GT5 (local) and GT20 (regional) levels for seismic events with M is greater than 2.5, including source geometry information and source depths. Towards meeting these objectives, seismograms from earthquakes in the Zagros Mountains recorded at regional distances have been inverted for moment tensors, which have then been used to create synthetic seismograms to determine the source depths of the earthquakes via waveform matching. The source depths have been confirmed by modeling teleseismic depth phases recorded on Global Seismographic Network (GSN) and International Monitoring System (IMS) stations. Early studies of the distribution of seismicity in the Zagros region found evidence for earthquakes in the upper mantle. But subsequent relocations of teleseismic earthquakes suggest that source depths are generally much shallower, lying mainly within the upper crust. All of the regional events studied so far nucleated within the upper crust, and most of the events have thrust mechanisms.


Descriptors :   *EARTH MODELS , SYMPOSIA , DETECTION , MIDDLE EAST , SEISMIC DATA , SEISMOGRAPHS , TENSORS , EARTHQUAKES , AFRICA , SURFACE TRUTH , PROPAGATION , CALIBRATION


Subject Categories : Geodesy


Distribution Statement : APPROVED FOR PUBLIC RELEASE