Earthquake focal mechanism and stress tensor analysis along the central segment of the North Anatolian fault

Download

index.pdf

Date

2010

Author

Karasözen, Ezgi

Metadata

Show full item record

Item Usage Stats

183
views

119
downloads

The North Anatolian Fault (NAF) is one of the world’s largest active continental strikeslip faults, and forms the northern margin of the Anatolian plate. Although its geologic and geomorphologic features are well defined, crustal deformation and associated seismicity around central segment of the NAF is relatively less-known. In this study, we analyzed locations and focal mechanisms of 172 events with magnitude ≥ 3, which are recorded by 39 broadband seismic stations deployed by the North Anatolian Passive Seismic Experiment (2005-2008). Distribution of the events shows that the local seismicity in the area is widely distributed, suggesting a widespread continental deformation, particularly in the southern block. For the entire data set, P- and S- arrival times are picked and events are relocated using the HYPOCENTER program. Then, relocated events which have a good azimuthal coverage with a maximum gap of 120° and at least 13 P- wave readings are selected and 1-D inversion algorithm, VELEST, is used to derive the 1-D seismic velocity model of the region. The final model with updated locations is later put together to the FOCMEC program, to obtain focal mechanisms solutions. In this step, an iterative scheme is applied by increasing the number of data errors. To obtain more unique solutions, first motions of P and SH v phases are used along with SH/P amplitude ratios. Resultant 109 well-constrained focal mechanisms later used to perform stress tensor inversion across the region. Our focal mechanisms suggest a dominant strike-slip deformation along two major fault sets in the region. In the east, E-W trending splays (Ezinepazarı, Almus, and Laçin Kızılırmak) show right-lateral strike-slip motion similar to the NAF whereas in the west, N-S trending faults (Dodurga, Eldivan) show left lateral strike-slip motion. Overall, stress orientations are found as: maximum principal stress, σ1, is found to be subhorizontal striking NW-SE, the intermediate principle stress, σ2, is vertically orientated and the minimum principal stress, σ3, is found to be NE –SW striking, consistent with the strike-slip regime of the region.

Subject Keywords

Earthquakes., Seismology.

URI

http://etd.lib.metu.edu.tr/upload/12612214/index.pdf
https://hdl.handle.net/11511/19865

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Earthquake Focal Mechanisms Along the Central Segment of the North Anatolian Fault Karasözen, Ezgi; Özacar, Atilla Arda; Biryol, C. Berk; Beck, Susan L.; Zandt, George (2010-05-02) The North Anatolian Fault (NAF) is one of the world’s largest active continental strike-slip faults, and forms the northern margin of the Anatolian plate. Although its geologic and geomorphologic features are well defined, crustal deformation and associated seismicity around central segment of the NAF is relatively less-known. In this study, we analyzed locations and focal mechanisms of over hundred events with magnitude ≥ 3, which are recorded by 39 broadband seismic stations deployed by the North Anatolia...
Preparation of a source model for the Eastern Marmara Region along the North Anatolian fault segments and probabilistic seismic hazard assessment of Düzce province Cambazoğlu, Selim; Akgün, Haluk; Department of Geological Engineering (2012) The North Anatolian Fault System is one of the most important active strike-slip fault systems in the world. The August 17, 1999 and November 12, 1999 earthquakes at Kocaeli and Düzce are the most recent devastating earthquakes. The study area lies in the Eastern Marmara Region and is bounded by the 28.55-33.75 E and 40.00-41.20 N, latitude and longitude coordinates, respectively. There are numerous studies conducted in the study area in terms of active tectonics and seismicity, however studies are scale de...
Earthquake Detection Near the Central Anatolian Fault Zone Using Continuous Data from the CD-CAT Experiment Russell, Joshua B.; Beck, Susan L.; Turkelli, Niyazi; Kalafat, Doğan; Özacar, Atilla Arda; Sandvol, Eric (2014-12-15) In central Turkey, the Anatolian plate is actively being pushed by Arabian plate convergence in the east and pulled by Hellenic arc retreat to the west; however, there is also ample evidence of internal plate deformation. This region provides an opportunity to gain a deeper understanding of the transition from collisional (eastern Anatolia) to escape tectonics (western Anatolia). The Continental Dynamics: Central Anatolian Tectonics (CD-CAT) experiment, consists of a dense array of 71 broadband seismometers...
Stress tensor inversion from focal mechanism solutions and earthquake probability analysis of Western Anatolia, Turkey Shah, Syed Tanvir; Özacar, Atilla Arda; Bozkurt, Erdin; Department of Geological Engineering (2015) Western Anatolia is one of the most important tectonic elements of Turkey, and constitutes the eastern margin of Aegean Extensional Province. The area is one of the most seismically active continental margins around the globe experiencing NS extension. Earthquake data in this study is used to analyze the active stress patterns and to estimate the earthquake probabilities for different sub-regions in western Anatolia. Various processing techniques to attain homogeneity are applied to the earthquake catalogu...
Displacements and Kinematics of the February 1, 1944 Gerede Earthquake (North Anatolian Fault System, Turkey): Geodetic and Geological Constraints Ayhan, Mehmet Emin; Kocyigit, Ali (2010-01-01) The North Anatolian Fault System (NAFS) is an approximately 2-110-km-wide, 1600-km-long right-lateral intra-continental transform fault boundary between the Anatolian platelet and the Eurasian plate. The Gerede fault zone is one of the major active structures in the western section of the NAFS. It is a 1-9-km-wide, 325-km-long and ENE-trending dextral strike-slip fault zone, with a total accumulated offset since its initiation (Late Pliocene) of about 43 km. This offset indicates an average geological slip ...

Citation Formats

E. Karasözen, “Earthquake focal mechanism and stress tensor analysis along the central segment of the North Anatolian fault,” M.S. - Master of Science, Middle East Technical University, 2010.