Oguz Ozel
Istanbul University
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Bulletin of the Seismological Society of America | 2002
Oguz Ozel; Edward Cranswick; Mark Meremonte; Mustafa Erdik; Erdal Safak
Approximately 1000 people were killed in the collapse of buildings in Istanbul, Turkey, during the 17 August 1999 Izmit earthquake, whose epicenter was roughly 90 km east of the city. Most of the fatalities and damage occurred in the suburb of Avcilar that is 20 km further west of the epicenter than the city proper. To investigate this pattern of damage, the U.S. Geological Survey, in cooperation with the Kandilli Observatory & Earthquake Research Institute (KOERI), deployed portable digital seismographs at seven free-field sites in western Istanbul, to record aftershocks during the period from 24 August to 2 September. The primary objective of this deployment was to study the site effects by comparing the aftershock ground motions recorded at sites inside and outside the damaged area, and to correlate site effects with the distribution of the damaged buildings. In addition to using weak-motion data, mainshock and aftershock acceleration records from the KOERI permanent strong-motion array were also used in estimating the site effects. Site effects were estimated using S waves from both types of records. For the weak-motion data set, 22 events were selected according to the criteria of signal-to-noise ratio (S/N ratio) and the number of stations recording the same event. The magnitudes of these events ranged from 3.0 to 5.2. The acceleration data set consisted of 12 events with magnitudes ranging from 4.3 to 5.8 and included two mainshock events. Results show that the amplifying frequency band is, in general, less than 4 Hz, and the physical properties of the geologic materials are capable of amplifying the motions by a factor of 5-10. In this frequency band, there is a good agreement among the spectral ratios obtained from the two mainshocks and their aftershocks. The damage pattern for the 17 August Izmit earthquake is determined by several factors. However, our study suggests that the site effects in Avcilar played an important role in contributing to the damage. Manuscript received 30 August 2000.
Journal of Earth System Science | 2014
Ferhat Ozcep; Savaş Karabulut; Oguz Ozel; Tazegul Ozcep; Nazire Imre; Halil Zarif
Yalova City (Turkey) is in a tectonically active location that is particularly affected by the northern branch of the North Anatolian Fault Zone. Magnitudes 7.4 and 7.2 earthquakes in 1999 caused great destruction in Yalova. The heavy damage to buildings and other civil engineering structures was mainly due to liquefaction-induced settlement and site effects such as resonance and amplification. In the first phase of this study, the soil liquefaction potential index (PL) and the induced soil settlement were estimated. In the second phase, the effects on sites in Yalova soil were investigated using microtremor and earthquake data. The fundamental periods and amplification in soft soil were compared with microtremor data and strong ground motion records obtained by a local array of eight accelerograph stations deployed in Yalova. Thirty-seven ‘single site’ ambient noise measurements were taken in a dense grid of points covering the centre of the city. A comparison between fundamental periods obtained from strong ground motion records and from microtremor measurements showed similarities, in the 0.1–5 Hz range. Finally, soil liquefaction and amplification (or resonance) were divided into regions according to the extent of damage and the geotechnical/geophysical results.
Seismological Research Letters | 2009
Kevin Fleming; Matteo Picozzi; C. Milkereit; F. Kühnlenz; Björn Lichtblau; Joachim Fischer; Can Zulfikar; Oguz Ozel
Geophysical Research Letters | 2009
Hakan Alcik; Oguz Ozel; Nurdan Apaydin; Mustafa Erdik
Soil Dynamics and Earthquake Engineering | 2009
Matteo Picozzi; A. Strollo; Stefano Parolai; Eser Durukal; Oguz Ozel; Savaş Karabulut; Jochen Zschau; Mustafa Erdik
Bulletin of Earthquake Engineering | 2010
Matteo Picozzi; C. Milkereit; Can Zulfikar; Kevin Fleming; Rocco Ditommaso; Mustafa Erdik; Jochen Zschau; Joachim Fischer; Erdal Şafak; Oguz Ozel; N. Apaydin
Earthquake Spectra | 2000
Erdal Safak; Mustafa Erdik; Kemal Beyen; David Carver; Edward Cranswick; Mehmet Çelebi; Eser Durukal; William L. Ellsworth; Thomas L. Holzer; Mark Meremonte; Charles S. Mueller; Oguz Ozel; Selcuk Toprak
Soil Dynamics and Earthquake Engineering | 2011
Hakan Alcik; Oguz Ozel; Yih-Min Wu; Nurcan Meral Ozel; Mustafa Erdik
International Journal for Housing Science and Its Applications | 2000
Edward Cranswick; Oguz Ozel; Mark Meremonte; Mustafa Erdik; Erdal Safak; Charles S. Mueller; Dee Overturf; Arthur D. Frankel
Journal of Applied Geophysics | 2016
Esref Yalcinkaya; Hakan Alp; Oguz Ozel; Ethem Görgün; Salvatore Martino; Luca Lenti; Celine Bourdeau; Pascal Bigarre; Stella Coccia