Proposition de Post-doc USIAS

Micro-seismicity in the Marmara Sea: a unique tracer for North Anatolian Fault deformation

Administrative information

Location: Institut de Physique du Globe de Strasbourg (EOST), France

Duration: 24 months (start: July 1st, 2015)

Advisors: O. Lengliné (MCF UNISTRA), J. Schmittbuhl (DR CNRS), H. Karabulut (visiting professor at EOST)

Contact: Olivier.lengline@unistra.fr, Jean.Schmittbuhl@unistra.fr

Address: IPGS, 5 rue René Descartes, 67084 Strasbourg, France

 

Applications should include a CV, a list of publications, a motivation letter, recommendation letters, names and contact details of two referees

 

 

Description:

 Istanbul is built on the shore of the Sea of Marmara, near the western part of the North Anatolian Fault (NAF), one of the most active continental faults in the world that limits two tectonic plates, Eurasia and Anatolia. This two thousand kilometers long fault has been the locus of nine major earthquakes since 1939. These earthquakes migrated westward into a unique spatio-temporal sequence where the last two major earthquakes (M 7.4 and M 7.2) occurred in 1999. It results that today, the Marmara region is a major seismic gap.

Starting in 2007, a dedicated local network has been progressively installed around the Marmara Sea in order to monitor the present day seismic activity of the region. This network is complemented with data from the permanent Turkish networks and the recent MARSITE network. Therefore, numerous data have been acquired in the past years and are still being recorded, producing a unique dataset for the region.

We propose to exploit the acquired data in order to resolve important questions related to the local tectonic environment. The diversity of the fault structures and the important earthquake activity renders this area a good natural site for studying earthquakes and creeping mechanisms. The aim of the post-doc will be dedicated to explore several aspects of the seismicity, notably: identifying precisely the active fault structures of the Marmara region from finely located seismicity, characterizing earthquake source mechanisms, and estimating micro-earthquake statistics (e.g. b-values, clustering, and seismicity rates). Extensive search for repeating events will also be performed. All observations will be discussed to highlight the possible locked and creeping portions of the Main Marmara Fault.  How earthquakes are related to creeping phase and if this can be related to seismicity burst, will be addressed by linking fault properties (rheology, nature of rocks, morphology) to the statistical properties of the seismicity and triggering efficiency. Comparisons with geodetic measurements will be tested and results will be compare to the San Andreas Fault, which is more directly accessible for direct creep measurements.

We will also investigate the nucleation process of the major regional earthquakes (presence of foreshocks, acceleration of seismicity, inference of slow slip, ...) and characterize how the seismicity vanishes at the brittle-ductile transition depth. The post-doctoral fellow will make extensive use of the earthquake database in order to characterize the various aspect of the seismicity. He/She will therefore provide new insights about the recent evolution of this important regional seismic gap.

 

Expected background: Seismology, seismic signal analysis, seismo-tectonics, fault mechanics, general programming/scripting skills

 

References:

[1] H. Karabulut, J. Schmittbuhl, S. Özalaybey, O. Lengliné, A. Kömeç-Multu, V. Durand, M. Bouchon, G. Daniel, , and M.P. Bouin. Evolution of the seismicity in the eastern marmara sea a decade before and after the 17 august 1999 izmit earthquake. Tectonophysics, 510(1-2):17-27, 2011.

[2] M. Bouchon, H. Karabulut, M. Aktar, S. Özalaybey, J. Schmittbuhl, and M.P. Bouin. Extended nucleation of the 1999 mw 7.6 izmit earthquake. Science, 82:877-880, 2011.