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Imaging the Mudurnu segment of the North Anatolian Fault Zone from waveforms of small earthquakes
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SYSNO ASEP 0486439 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Imaging the Mudurnu segment of the North Anatolian Fault Zone from waveforms of small earthquakes Author(s) Najdahmadi, B. (DE)
Hrubcová, Pavla (GFU-E) ORCID, RID
Vavryčuk, Václav (GFU-E) ORCID, RID
Bohnhoff, M. (DE)Source Title Journal of Geophysical Research-Solid Earth. - : Wiley - ISSN 2169-9313
Roč. 123, č. 1 (2018), s. 493-512Number of pages 20 s. Publication form Print - P Language eng - English Country US - United States Keywords local seismicity ; North Anatolian Fault Zone ; seismic waveform processing ; converted PS phases ; polarization analysis ; secondary phases in P wave coda Subject RIV DC - Siesmology, Volcanology, Earth Structure OECD category Volcanology R&D Projects GA17-19297S GA ČR - Czech Science Foundation (CSF) GC16-19751J GA ČR - Czech Science Foundation (CSF) Institutional support GFU-E - RVO:67985530 UT WOS 000426132600029 EID SCOPUS 85042284183 DOI 10.1002/2017JB015198 Annotation We analyze waveforms of local earthquakes occurring before, between, and after the two consecutive 1999 M-w>7 zmit and Duzce earthquakes in NW Turkey. The waveforms were recorded at three seismic stations DOK, EKI, and GOK located around the Mudurnu segment of the North Anatolian Fault Zone. We focus on the interpretation of a distinct secondary phase contained in the P wave coda that is well separated from the direct P wave. The phase is visible in many waveforms of most seismicity clusters and has a specific constant time delay after the direct P wave arrivals at each station, irrespective of epicentral distance, hypocentral depth, or back azimuth. Based on a polarization analysis of records at station GOK, this secondary phase is interpreted as a PS wave converted at an interface near the stations. Its particle motion is consistent with the direct S wave and displays S wave splitting produced by the anisotropic upper crust. Synthetic modeling indicates that this PS phase can be converted either at a horizontal interface or at a steeply inclined interface. The steep Mudurnu fault zone with the near-surface setting indicating a juvenile pull-apart structure fits well into these interpretations, which are in agreement with the eastward progressing transtensional tectonics known for the region. Workplace Geophysical Institute Contact Hana Krejzlíková, kniha@ig.cas.cz, Tel.: 267 103 028 Year of Publishing 2019
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