Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Interpretation Of Ground Response And Shear-Wave Velocity (Vs) Structure in

Microzonatıon Studies: A Case Study in Eskişehir

Earthquakes in our country and in the world cause damage and collapse of engineering structures due to several reasons. Settlement areas are under the effect of strong and long-duration seismic vibrations due to resonance and focusing effects.

Eskişehir city-center is chosen as the study area where an earthquake of 6.4 magnitude happened on February, 20 1956 damaged 2819 constructions. During the August, 17 1999 Kocaeli Earthquake, 86 lives were lost, and 95 injuries occurred in the Eskisehir city-center. 70 residences-enterprises were heavily damaged, 1 building during the earthquake, 4 buildings following the earthquake were collapsed. The reason of the extensive damage caused by the 1999 Kocaeli Earthquake 130 km far from Eskişehir is still under investigation. The main reason of those damages is local site-effects. The aim of this study is to determine the effect by using of geophysical methods.
The most important parameters to determine local soil effects are the shear-wave velocity (Vs), sediment tickness (h), and dominant frequency (f). Subsurface S wave velocity model may be computed from the inversion dispersion curves derived from Rayleigh waves. In this study, single/multiple station microtremor measurement methods which are more practical, non-distructive, fast and economical compared to other methods were implemented. These methods using microtremor recordings have become a very useful data for microzonation studies because of their simple acquisition and analysis. Dominant frequency (f), bed-rock depth (h) and shear-wave velocity (Vs) were determined from H/V spectral ratio and Spatial Autocorrelation (SPAC) methods. The results obtained were compared to the 96-channel seismic reflection data with explosive energy source. Two separate formulae, defining the relation between sediment thickness (h) and dominent frequency (f) for two layered structure (bed-rock depth ‘h₁’, soft soil layer ‘h₂’), were developed based on the data obtained from shallow- and deep-drill data.
Trias metamorphic rocks on the north, and Pliocene, Miocene, Eocene sedimentary rocks on the south of the study area outcrop. Quaternary age of units constitute the upper-level of the Eskişehir valley. In this study, single station microtremor (H/V) measurement results, which were collected by university, are analyzed and with the help of these data, a complete fundamental frequency map has been prepared for the study area. This map was compared with a regional geological map and the higher frequency area indicated that is near to the surface of bedrock. First-pick on the H/V spectral ratio curve is related to the Trias rock outcrops at the north of the study area, second-pick on the H/V spectral ratio curve is related to the Quaternary new aluvium deposited by the Porsuk River and Sarısu Creek. The compliance between measured frequency values and Vs models versus geological structure were investigated.
  

ÖKSÜM Erdinç
Tez Adı : İstanbul Fragmanının Ordovisiyen Dönemindeki Tektonik Evriminin

Paleomağnetik Verilerle Belirlenmesi

Danışman : Prof. Dr. Z. Mümtaz HİSARLI

Anabilim Dalı : Jeofizik Mühendisliği

Programı : -

Mezuniyet Yılı : 2013

Tez Savunma Jürisi : Prof. Dr. Z. Mümtaz Hisarlı

Prof. Dr. Naci ORBAY

Prof. Dr. Oya ÇAKIN

Prof. Dr. Hayrettin KORAL

Doç. Dr. M. Nuri DOLMAZ