Caucasus Seismic Information Network: Data and Analysis Final Report

Randolph Martin ; Mary Krasovec ; Spring Romer ; Timothy O'Connor ; Emanuel G. Bombolakis ; Youshun Sun ; Nafi Toksoz

关键词: ARMENIA;    AZERBAIJAN;    REPUBLIC OF GEORGIA;    GEOLOGY;    SEISMIC WAVES;    SEISMICITY;    GEOLOGIC MODELS;    TECTONICS;    WAVE PROPAGATION;    GEOLOGIC FAULTS;    MAPS Caucasus;    seismicity;    crustal structure;    tectonics;    active faulting;    regional networks;    seism;   

DOI  :  10.2172/899760
RP-ID  :  DOE/NA/99600-1
PID  :  OSTI ID: 899760
Others  :  TRN: US200821%%244

学科分类：地球科学(综合)

美国|英语

来源: SciTech Connect

【 摘 要 】

The geology and tectonics of the Caucasus region (Armenia, Azerbaijan, and Georgia) are highly variable. Consequently, generating a structural model and characterizing seismic wave propagation in the region require data from local seismic networks. As of eight years ago, there was only one broadband digital station operating in the region – an IRIS station at Garni, Armenia – and few analog stations. The Caucasus Seismic Information Network (CauSIN) project is part of a nulti-national effort to build a knowledge base of seismicity and tectonics in the region. During this project, three major tasks were completed: 1) collection of seismic data, both in event catalogus and phase arrival time picks; 2) development of a 3-D P-wave velocity model of the region obtained through crustal tomography; 3) advances in geological and tectonic models of the region. The first two tasks are interrelated. A large suite of historical and recent seismic data were collected for the Caucasus. These data were mainly analog prior to 2000, and more recently, in Georgia and Azerbaijan, the data are digital. Based on the most reliable data from regional networks, a crustal model was developed using 3-D tomographic inversion. The results of the inversion are presented, and the supporting seismic data are reported. The third task was carried out on several fronts. Geologically, the goal of obtaining an integrated geological map of the Caucasus on a scale of 1:500,000 was initiated. The map for Georgia has been completed. This map serves as a guide for the final incorporation of the data from Armenia and Azerbaijan. Description of the geological units across borders has been worked out and formation boundaries across borders have been agreed upon. Currently, Armenia and Azerbaijan are working with scientists in Georgia to complete this task. The successful integration of the geologic data also required addressing and mapping active faults throughout the greater Caucasus. Each of the major faults in the region were identified and the probability of motion were assessed. Using field data and seismicity, the relative activity on each of these faults was determined. Furthermore, the sense of motion along the faults was refined using GPS, fault plane solutions, and detailed field studies. During the course of the integration of the active fault data, the existence of the proposed strike slip Borjomi-Kazbeki fault was brought into question. Although it had been incorporated in many active tectonic models over the past decade, field geologists and geophysicists in Georgia questioned its existence. Detailed field studies were carried out to determine the existence of the fault and estimate the slip along it; and it was found that the fault zone did not exist. Therefore, the convergence rate in the greater Caucasus must be reinterpreted in terms of thrust mechanisms, instead of strike-slip on the Borjomi-Kazbeki fault zone.