3-D crustal structure along the North Anatolian Fault Zone in north-central Anatolia revealed by local earthquake tomography


Creative Commons License

Yolsal Çevikbilen S., Biryol C. B. , Beck S., Zandt G., Taymaz T., Adiyaman H. E. , ...More

GEOPHYSICAL JOURNAL INTERNATIONAL, vol.188, no.3, pp.819-849, 2012 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 188 Issue: 3
  • Publication Date: 2012
  • Doi Number: 10.1111/j.1365-246x.2011.05313.x
  • Title of Journal : GEOPHYSICAL JOURNAL INTERNATIONAL
  • Page Numbers: pp.819-849
  • Keywords: Seismicity and tectonics, Body waves, Seismic tomography, Continental tectonics: strike-slip and transform, Crustal structure, BASIN CENTRAL ANATOLIA, VELOCITY STRUCTURE, INTERNAL DEFORMATION, TECTONIC EVOLUTION, SEISMIC TOMOGRAPHY, ACTIVE TECTONICS, CENTRAL TURKEY, BENEATH, SUBDUCTION, REGION

Abstract

3-D P-wave velocity structure and Vp/Vs variations in the crust along the North Anatolian Fault Zone (NAFZ) in north-central Anatolia were investigated by the inversion of local P- and S-wave traveltimes, to gain a better understanding of the seismological characteristics of the region. The 3-D local earthquake tomography inversions included 5444 P- and 3200 S-wave readings obtained from 168 well-located earthquakes between 2006 January and 2008 May. Dense ray coverage yields good resolution, particularly in the central part of the study area. The 3-D Vp and Vp/Vs tomographic images reveal clear correlations with both the surface geology and significant tectonic units in the region. We observed the lower limit of the seismogenic zone for north-central Anatolia at 15 km depth. Final earthquake locations display a distributed pattern throughout the study area, with most of the earthquakes occurring on the major splays of the NAFZ, rather than its master strand. We identify three major high-velocity blocks in the mid-crust separated by the Izmir-Ankara-Erzincan Suture and interpret these blocks to be continental basement fragments that were accreted onto the margin following the closure of Neo-Tethyan Ocean. These basement blocks may have in part influenced the rupture propagations of the historical 1939, 1942 and 1943 earthquakes. In addition, large variations in the Vp/Vs ratio in the mid-crust were observed and have been correlated with the varying fluid contents of the existing lithologies and related tectonic structures.