Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Investigation of Istanbul Çatalca Region Faults by Magnetotelluric Method

Thrace Region representing the most northwestern Turkey contains many Southeast-Northwest oriented strike slip faults. Also at the Catalca Region where our studies take place, at the western side of Istanbul a Southeast-Northwest oriented en-echelon fault shows itself at the surface. Catalca Region is the place where the Thrace basin ends, most eastern extensions of Istranca (Strandja) Massive observed and Istanbul-Zonguldak Zone starts. The idea that the suture between these two zones represented by a major continental fault which is covered by sediments, is a commonly accepted by the most geologists. This major fault is thought to be at the eastern side of the Catalca Fault but the exact inland place of this fault is not going further of being estimation. In spite of the fact that the region is investigated many times before, there are not any study which gave deep resistivity cross-sections. The purpose of this work is to reveal the resistivity structure beneath the surface, determining boundaries and making interpretations on them.

In that purpose between 28 April and 4 May 2007 magnetotelluric studies carried on and two Phoenix MTU-5A magnetotelluric measuring devices which are provided by Bogazici University, Kandilli Observatory and Earthquake Research Institute are used on a single ~30 kms long Southwest-Northeast profile contains nine measuring points and crosses the fault in the region (Catalca Fault) perpendicularly. Then the data is processed, inverted in 2-D and resistivity cross-sections obtained. We compared and correlated our magnetotelluric (MT) model to geologic information and defined horizontal-vertical boundaries of the units.

As the result of the study, thicknesses of the sediments, place of the Catalca Fault, change of the geologic strike with depth and resistivities of geological units are determined.

At the east of the Catalca Fault a sediment zone has an increasing thickness up to 700 m determined. A conductive zone extending trough depth developed due to Catalca Fault showed itself at the east of Elbasan station. At the most southwestern part of the profile another conductive zone determined and interpreted as sediments with steeply increasing thickness developed in relation to a fault. Beneath Yassıören and Baklalı stations a vertical conductive boundary determined and its thought to be representing a suture; West Black Sea Fault, which is geologically controversial and in lack of geophysical measurements taken before.

  

FIRAT Berrak

Danışman : Yard.Doç.Dr. Naşide ÖZER

Anabilim Dalı : Jeofizik Mühendisliği

Mezuniyet Yılı : 2008

Tez Savunma Jürisi : Yard.Doç.Dr. Naşide ÖZER

Prof.Dr. Demir KOLÇAK

Prof.Dr. Yıldız ALTINOK

Doç.Dr. Oğuz ÖZEL

Doç.Dr. Hayrettin KORAL