Stress Inversion of Regional Seismicity in the Sea of Marmara Region, Turkey

Abstract

In this study we derive the stress tensor and its local variations throughout the Marmara region, Turkey. Based on a recently compiled 10-year earthquake catalogue, we directly invert first-motion polarity data and quantify confidence intervals for the principal stress orientations. We find a combined strike-slip and normal faulting stress field for the Marmara region generally reflecting the overall transtensional setting. However, the results clearly show moderate local variations of the stress field. The largest (r 1) and intermediate (r 2) principal stresses show an average regional trend of N125 E and locally varying plunges. The least principal stress (r 3) is well resolved in its confidence interval and consistent throughout the region with an average trend of $ N35 E and a subhorizontal plunge. The eastern Sea of Marmara shows local stress field orientations with pronounced strike-slip (northern part) and normal faulting (southern part) components. Along the central Marmara region, normal faulting tends to dominate, while a well resolved strike-slip stress regime is found in the western Sea of Marmara region. Regarding the faulting mechanism of an earthquake with magnitude up to 7.4 which is expected in this area in direct vicinity of the Istanbul metropolitan region, our results imply that neither strike-slip nor normal faulting kinematics can be excluded.

A numerical study on seismic risk assessment of historic masonry towers: a case study in İstanbul

“…The northern strand of the NAF is reaching the conclusion of its seismic phase given the normal recurrence period of about 250 years [13,14]. Istanbul is reportedly under threat from an earthquake with a magnitude of Mw 7.0 [15]. Four earthquakes with magnitude of 9 or higher occurred in Istanbul and its surroundings between the 16th and 20th centuries, according to the Historical Earthquake Catalogue for Turkey [5].…”

Influence of site-specific probabilistic seismic hazard on the risk assessment of a masonry tower

“…The northern strand of the NAF is reaching the conclusion of its seismic phase given the normal recurrence period of about 250 years (Parsons 2004, Bohnhoff et al 2016. Istanbul is reportedly under threat from an earthquake with a magnitude of Mw 7.0 (Wollin 2019). Four earthquakes with magnitude of 9 or higher occurred in Istanbul and its surroundings between the 16th and 20th centuries, according to the Historical Earthquake Catalogue for Turkey (Polat and Saygili 2020).…”

Analysis of seismic parameters for the earthquake vulnerability assessment of Nusretiye (Tophane) Clock Tower

“…Considering the average recurrence time about 250 years northern strand of the NAF is presently in the homestretch of its seismic period (Parsons, 2004;Bohnhoff et al, 2016). It is believed that an earthquake with a magnitude of Mw 7.0 threatens the city of Istanbul (Wollin et al 2019). Seismicity of the select region is given in Figure 3a which covers the period between 1900 and 2020.…”