Atilla Ansal

Editorial and welcome to a new ERA

With this first issue of Volume 13 (2015), while we are celebrating our 12th anniversary, we will be implementing some major changes for BEE. We are going to start publishing on a monthly basis with 12 issues per year and introduce eight new Associate Editors. I would like to take this opportunity to welcome the eight Associate Editors who will be sharing the Editorial responsibilities. It has been an exciting and inspiring twelve years. This would not have been possible without the contributions of the distinguished BEE Editorial Board Members, distinguished authors of the published manuscripts and the competent, dedicated reviewers. I would like to express my utmost gratitude and thanks to the retiring Editorial Board Members and to all those who made this possible. Furthermore, I would like to expressmy and our gratitude and thanks to Springer, specially to Petra D. van Steenbergen, Senior Publishing Editor of Earth Sciences, to Stefan van Dijl, Desk Editor, and to Cynthia Clement, JEO Assistant from the Journals Editorial Office for their continuous contributions, interest, and support. During these past twelve years, approximately 1,500 manuscripts were submitted to BEE. The number of submitted manuscripts has increased continuously from 26 in 2003 to 305 in 2013. With respect to published articles: the first BEE volume in 2003 included 16 articles. The number of published articles increased to 133 in volume 12 in 2014. We started with an impact factor of 1.125 for 2007 which was the second highest among the five earthquake engineering journals (Earthquake Engineering and Structural Dynamics, Bulletin of Earthquake Engineering, Earthquake Spectra, Soil Dynamics and Earthquake Engineering, Journal of Earthquake Engineering) at that time. Our impact factor increased continuously over the following years to 1.701 for 2010. Most likely due to the increasing number of published articles, our impact factor first dropped to 1.559 for 2011, 1.560 for 2012 and 1.368 for 2013. However, like in the previous years also in 2013, we ranked again as the second highest amongst the six SCI earthquake engineering journals (Earthquake Engineering and Engineering Vibration was added to the previous list).

Preface to the second decade

With this first issue of 2013 (Vol. 11 No.1), we are celebrating our tenth anniversary, our first decade. It has been ten exciting and inspiring years. This would not have been possible without the contributions of the distinguished BEE Editorial Board, distinguished authors of the published manuscripts and the competent, dedicated reviewers. I like to express my utmost gratitude and thanks to all who made this possible. Furthermore, I would like to expressmy and our gratitude and thanks to Springer, specially to Petra D. van Steenbergen, Senior Publishing Editor of Earth Sciences, to Stefan van Dijl, Desk Editor, and to Geetha Subramanian, JEO Assistant from Journals Editorial Office for their continuous contributions, interest, and support. During these past ten years, approximately 1,000 (to be exact 961) manuscripts were submitted for publication to BEE. The number of submitted manuscripts has increased continuously from 26 in 2003 and 2004, to 38 in 2005, 51 in 2006, 65 in 2007, 107 in 2008, 126 in 2009, 150 in 2010, 154 in 2011, and 243 in 2012. With respect to printed manuscripts; the first BEE volume in 2003 had 16, the second volume in 2004 had 15, and the third volume in 2005 had 12 articles. Due to the increase in the number of annual issues to four, the fourth volume in 2006 had 25, the fifth volume in 2007 had 27, the sixth volume in 2008 had 34, and the seventh volume in 2009 had 33 articles. In 2010, we have started to publish six issues and the number of published articles increased to 77 in 2010, 94 in 2011 and 88 in 2012. Approximately 4years after we started to publish BEE, I was informed on November 4, 2006 by Springer that BEE has been selected by ISI and will be included in SCIE and CC/Engineering, Computing, and Technology starting from the first issue of 2007.We started with the impact factor of 1.125 for 2007 which was the second highest among the five earthquake engineering journals (Earthquake Engineering and Structural Dynamics, Bulletin of Earthquake Engineering, Earthquake Spectra, Soil Dynamics and Earthquake Engineering, Journal of Earthquake Engineering) at that time. Our impact factor increased continuously in the following years to 1.271 for 2008, 1.339 for 2009, 1.701 for 2010 and 1.559 for

Special issue in memory of Nicholas Ambraseys

Nicholas (Nick) Ambraseys was born in Athens (Greece) on 19th January 1929 and died peacefully at his home in Putney (London, United Kingdom) on 28th December 2012 at the age of 83. Nick attended the National Technical University of Athens, receiving his diploma in Rural Engineering in 1952. Following this and service in the Royal Hellenic Navy, he moved to Imperial College in London to study in the Soil Mechanics section of the Department of Civil Engineering for his Diploma of Imperial College and later his PhD, which he was awarded in 1958. Following a few years at universities in Greece and in the United States of America he returned to Imperial College and remained there until his death. He was made Professor of Engineering Seismology in 1974. In 1968 he established the Engineering Seismology section in the Department of Civil Engineering and from 1971 to 1994 he led this section. In 1994 he officially retired but he remained very active as an Emeritus Professor and his publications continued at an undiminished rate. Nick’s contributions to engineering seismology and earthquake engineering were immense, wide-ranging and spanned almost 60years.

Site specific response analysis for performance based design earthquake characteristics

During strong earthquakes, seismic waves travelling towards the ground surface alter the engineering characteristics of the soil layers and consequently the characteristics of travelling seismic waves also change with respect to their frequency and amplitude contents. In assessing the site-specific design earthquake characteristics in seismically active zones for performance levels of Collapse Prevention, Life Safety, and Immediate Occupancy that may correspond to 72, 475 and 2475 year return period earthquakes, detailed site characterization and site response analyses may be required. This process may be conducted in two consecutive statistically independent stages. The first stage involves the seismic hazard study to assess the design earthquake characteristics on rock outcrop for selected exceedance levels and the second stage involves detailed site characterization and site response analyses to estimate design earthquake characteristics on the ground surface. The uncertainties arising from the source characteristics need to be taken into account by using a representative number of strong motion acceleration records for site response analyses recorded in locations that are compatible with the seismic hazard with respect to fault mechanism, earthquake magnitude, and source distance. In addition, the strong motion acceleration records should be compatible with respect to peak acceleration and acceleration response spectra levels estimated by the probabilistic or deterministic seismic hazard study. One approach is to use the uniform acceleration hazard spectra and another option is to adopt conditional mean spectrum on rock outcrop estimated in the first stage from the earthquake hazard study for scaling input motions for site response analysis. It was observed that the scaling methodology adopted may play an important role in the calculated earthquake characteristics on the ground surface. A semi empirical procedure was proposed to determine the site specific design earthquake characteristics on the ground surface. A parametric study was conducted to demonstrate the applicability of the proposed methodology based on one dimensional site response analyses using Shake91 and DeepSoil site response codes to evaluate design earthquake characteristics on the ground surface.

Site response from Istanbul vertical arrays and strong motion network

In the framework of Istanbul Microzonation Project for the European side, the investigated region was divided by a grid system of 250m×250m and site investigations were performed for each cell based on borings and in-situ seismic wave velocity measurements for defining representative soil profiles with shear wave velocity values extending down to the engineering bedrock. Geological and geotechnical laboratory and field testing data with measured seismic wave velocities enabled to determine the engineering properties of the soil and rock layers encountered in all the cells. There have been limited number of earthquakes within 100km range of Istanbul with local magnitude in the range of ML=4-5 and few more distant and more stronger earthquakes that were recorded by the existing three vertical arrays as well as by the Istanbul Rapid Response Network (IRRN) strong motion stations. Even though the maximum PGA were similar, the observed spectral response were different indicating the importance of the distance and source magnitude concerning the frequency content and predominant soil period ranges. Even though the level of ground shaking intensity is relatively low, efforts were made to evaluate the variation of the recorded accelerations with depth in vertical arrays located at Ataköy, Zeytinburnu and Fatih. Attempts were also made to model the recorded acceleration time histories at the triggered IRRN stations using the acceleration records obtained at the bedrock level from the vertical array stations in the case of the recent 19.5.2011 Mw=5.7 Kütahya earthquake that took place approximately 185km away. 1 Professor, Dept. of Civil Engineering, Ozyegin University, Istanbul, Turkey, e-mail:atilla.ansal@ozyegin.edu.tr 2 Assoc. Professor, Dept. of Civil Engineering, Ozyegin University, Istanbul, Turkey 3 Research Assoc. Dr., Bogazici Uni. Kandilli Observatory and Earthquake Research Institute, Istanbul, Turkey Ansal A, Kurtulus A, Tönük G. Site Response From Istanbul Vertical Arrays And Strong Motion Network. Proceedings of the 10 National Conference in Earthquake Engineering, Earthquake Engineering Research Institute, Anchorage, AK, 2014 Site Response From Istanbul Vertical Arrays And Strong Motion Network A.Ansal , A.Kurtulus , and G.Tönük ABSTRACT In the framework of Istanbul Microzonation Project for the European side, the investigated region was divided by a grid system of 250m×250m and site investigations were performed for each cell based on borings and in-situ seismic wave velocity measurements for defining representative soil profiles with shear wave velocity values extending down to the engineering bedrock. Geological and geotechnical laboratory and field testing data with measured seismic wave velocities enabled to determine the engineering properties of the soil and rock layers encountered in all the cells. There have been limited number of earthquakes within 100km range of Istanbul with local magnitude in the range of ML=4-5 and few more distant and more stronger earthquakes that were recorded by the existing three vertical arrays as well as by the Istanbul Rapid Response Network (IRRN) strong motion stations. Even though the maximum PGA were similar, the observed spectral response were different indicating the importance of the distance and source magnitude concerning the frequency content and predominant soil period ranges. Even though the level of ground shaking intensity is relatively low, efforts were made to evaluate the variation of the recorded accelerations with depth in vertical arrays located at Ataköy, Zeytinburnu and Fatih. Attempts were also made to model the recorded acceleration time histories at the triggered IRRN stations using the acceleration records obtained at the bedrock level from the vertical array stations in the case of the recent 19.5.2011 Mw=5.7 Kütahya earthquake that took place approximately 185km away.In the framework of Istanbul Microzonation Project for the European side, the investigated region was divided by a grid system of 250m×250m and site investigations were performed for each cell based on borings and in-situ seismic wave velocity measurements for defining representative soil profiles with shear wave velocity values extending down to the engineering bedrock. Geological and geotechnical laboratory and field testing data with measured seismic wave velocities enabled to determine the engineering properties of the soil and rock layers encountered in all the cells. There have been limited number of earthquakes within 100km range of Istanbul with local magnitude in the range of ML=4-5 and few more distant and more stronger earthquakes that were recorded by the existing three vertical arrays as well as by the Istanbul Rapid Response Network (IRRN) strong motion stations. Even though the maximum PGA were similar, the observed spectral response were different indicating the importance of the distance and source magnitude concerning the frequency content and predominant soil period ranges. Even though the level of ground shaking intensity is relatively low, efforts were made to evaluate the variation of the recorded accelerations with depth in vertical arrays located at Ataköy, Zeytinburnu and Fatih. Attempts were also made to model the recorded acceleration time histories at the triggered IRRN stations using the acceleration records obtained at the bedrock level from the vertical array stations in the case of the recent 19.5.2011 Mw=5.7 Kütahya earthquake that took place approximately 185km away. Introduction The first stage of the Istanbul Microzonation Project involved detailed microzonation studies that were conducted on the European side of the city [1]. The investigated region was divided by a grid system into cells of 250m×250m and detailed site investigations were conducted in each cell based on borings and in-situ measured seismic wave velocities for defining representative soil profiles with shear wave velocity values extending down to the engineering bedrock [2]. The Istanbul Rapid Response Network (IRRN) composed of strong motion stations distributed more or less evenly with the metropolitan city of Istanbul. 55 of these strong motion stations are located within the area where detailed microzonation study was conducted [3]. In 1 Professor, Dept. of Civil Engineering, Ozyegin University, Istanbul, Turkey, e-mail:atilla.ansal@ozyegin.edu.tr 2 Assoc. Professor, Dept. of Civil Engineering, Ozyegin University, Istanbul, Turkey 3 Research Assoc. Dr., Bogazici Uni. Kandilli Observatory and Earthquake Research Institute, Istanbul, Turkey Ansal A, Kurtulus A, Tönük G. Site Response From Istanbul Vertical Arrays And Strong Motion Network. Proceedings of the 10 National Conference in Earthquake Engineering, Earthquake Engineering Research Institute, Anchorage, AK, 2014 addition three vertical arrays were installed in the same area at Ataköy, Zeytinburnu and Fatih extending all the way down to the engineering bedrock (Vs > 750m/s) as in Figure 1 [4,5,6,7,8]. There have been limited number of earthquakes within 100km range of Istanbul with local magnitude in the range of ML=4-5 and few more distant and more stronger earthquakes that were recorded by the existing three vertical arrays as well as by the Istanbul Rapid Response Network (IRRN) strong motion stations. The stations that recorded the evaluated two events Cınarcık and Kütahya earthquakes are also shown in Figure 1. Figure 1. The distribution of IRRN strong motion stations and the locations of the three vertical arrays within the detailed microzonation area on the European side of Istanbul. Çınarcık and Kütahya Earthquakes During the recent years, Istanbul has experienced limited amount of minor earthquakes. Among these, the highest peak ground accelerations were produced by the ML=4.8 Çınarcık earthquake that took place on 12/03/2008. It was a shallow event with focal depth about 11km, generated by strike-slip movement of one segment of the North Anatolian Fault in the Marmara Region. On the other hand, the Mw=5.7 Kutahya Earthquake of 19.5.2011 were the strongest but distant earthquake recorded by the three vertical arrays. The epicenter distances for these two events were significantly different, Cinarcık epicenter was about 43km while the Kutahya epicenter was about 205km away. As a result as shown in Figure 2, the predominant periods based on acceleration spectra for these two events recorded by the Atakoy vertical array were significantly different due to the differences in the triggering dominant wave frequencies. These two events, even though the PGA at the bedrock level was very similar, in the range of 7mg, indicate that the frequency content and predominant site periods can be significantly different even at the same level of ground shaking and thus is controlled mainly by the source distance and magnitude rather than local site conditions. The effect of distance has introduced differences not in the recorded peak ground accelerations but rather in the frequency content of the acceleration time history and thus in elastic acceleration response spectra as shown in Figure 2. This observation indicates the importance of distance resulting in filtering the higher frequency content of the earthquake ground motion. Thus the definition of predominant periods based on near field small earthquakes and noise measurements may be questionable with respect to the definition of predominant soil periods. The predominant soil periods are very dependent on input ground motion characteristics and thus the use of noise measurements may not always give reliable results with respect to the effects of local site conditions. Figure 2. Acceleration response spectra at different depths for (a) ML=4.8 Çınarcık Earthquake of 12.3.2008 (b) Mw=5.7 Kütahya Earthquake of 19.3.2011 at Ataköy Vertical array. The Mw=5.7 Kütahya Earthquake of 19.5.2011 was the first event that is recorded by all three vertical arrays. Even though the meas

Implications of Site Specific Response Analysis

Definition of design earthquake characteristics, more specifically uniform hazard acceleration response spectrum, on the ground surface is the primary component for performance based design of structures and assessment of seismic vulnerabilities in urban environments. The adopted approach for this purpose requires a probabilistic local seismic hazard assessment, definition of representative site profiles down to the engineering bedrock, and 1D or 2D equivalent or nonlinear, total or effective stress site response analyses depending on the complexity and importance of the structures to be built. Thus, a site-specific response analysis starts with the probabilistic estimation of regional seismicity and earthquake source characteristics, soil stratification, engineering properties of encountered soil layers in the soil profile. The local seismic hazard analysis would yield probabilistic uniform hazard acceleration response spectrum on the bedrock outcrop. Thus, site specific response analyses also need to produce a probabilistic uniform hazard acceleration response spectrum on the ground surface. A general review will be presented based on the previous studies conducted by the author and his co-workers in comparison to major observations and methodologies to demonstrate the implications of site-specific response analysis.

A Simplified Approach for Site-Specific Design Spectrum

The design acceleration spectrum requires site investigations and site-response analyses in accordance with the local seismic hazard. The variability in earthquake source and path effects may be considered using a large number of acceleration records compatible with the earthquake hazard. An important step is the selection and scaling of input acceleration records. Likewise, a large number of soil profiles need to be considered to account for the variability of site conditions. One option is to use Monte Carlo simulations with respect to layer thickness and shear wave velocity profiles to account for the variability of the site factors. The local seismic hazard analysis yields a uniform hazard acceleration spectrum on the bedrock outcrop. Site-specific response analyses also need to produce a uniform hazard acceleration spectrum on the ground surface. A simplified approach is proposed to define acceleration design spectrum on the ground surface that may be considered a uniform hazard spectrum.

Eulogy to Professor Michele Maugeri

Our very dear colleague Michele Maugeri, author and Guest Editor for the Special Issue on “Performance Based Design in Earthquake Geotechnical” passed away on November 1, 2014. He was born in Acireale (Sicily) in 1944, he got his degree in Civil Engineering from the Politecnico di Torino, winning the award for the best thesis (“Technical aspects of a bridge across the Messina Strait”) and the second prize in an international competition for the fixed link road and railway between Sicily and the mainland. His brilliant academic career developed at the University of Catania, where he was teaching since 1972, becoming Associate Professor in 1979 and then Full Professor of Geotechnical Engineering in 1990. His career was full of countless tasks of primary importance: he was a member of the Board of Public Works, member of the National Commission UNI “Construction Structural Engineering”, member of the Task Group no. 6 on “Geotechnical Earthquake Engineering and Microzonation” of the European Association for Earthquake Engineering, chairman of the “ERTC 12—Evaluation of Geotechnical Aspects of EC8”. He was also active member of scientific and organizing committees of numerous national and international conferences, including the ‘2008 Seismic Engineering International Conference commemorating the 1908 Messina and Reggio Calabria Earthquake (MERCEA08)’.

Eulogy to Professor Nicholas N. Ambraseys

Sadly, at the final phase of all the preparations for Vol.11 N.1, our very dear and very distinguished Editorial Board Member Prof. Nicholas Ambraseys passed away on December 28, 2012 at the age of 83. Prof. Ambraseys played a very positive and crucial role in the initiation of the Bulletin of Earthquake Engineering ten years ago. He attended the EAEE Executive Committee Meeting held in Lisbon on September 16, 2000 and supported the publication of a new technical journal as the official journal of EAEE. As the Editorial Board of BEE, we believe it would be very appropriate to dedicate this issue to our great mentor, colleague and great researcher, Professor Nicholas Ambraseys. He recently submitted two manuscripts to be published in BEE. The first one “Assessment of the long-term seismicity of Athens from two classical columns” was published in the V.10 N.6 (2012). The second one “Ottoman archives and the assessment of the seismicity of Greece 1456–1833” is in the review stage. Professor Ambraseys was born in Athens and raised in Alexandria, received his diploma in engineering at the National Technical University of Athens in 1952 and then Civil Engineering at Imperial College specialising in Soil Mechanics and Engineering Seismology. He obtained his PhD degree in 1958. Early in his career (between 1958 & 68) he served as young faculty (Assist. Prof.) at the Civil Engineering Dept. of the University of Illinois and also as Professor of Civil Engineering Dept. at the National University of Athens. He later joined Imperial College as a Lecturer and he was appointed as Reader in Engineering Seismology in 1968 and full Professor of Engineering Seismology in 1974. He retired in 1994 and became Emeritus Professor of Engineering Seismology and Senior Research Fellow at Imperial College London. Since few years he was a member of the Academy of Athens (one out of only two engineers in that small and nationally prestigious body), commuting between London & Athens.