Finite-fault Waveform Inversion of the May 24, 2014 Northern Aegean Sea Earthquake (Mw = 6.9)

Bu çalışmada 24 Mayıs 2014 Kuzey Ege Denizi depreminin kırılma özellikleri telesismik P ve SH dalga şekilleri kullanılarak araştırılmıştır. Ters çözüm sonuçları depremin iç merkezinin KD yönünde konumlanan üç fay pürüzünün yenilmesi nedeniyle oluştuğu belirlenmiştir. Depremin iç merkezine en yakın pürüz 10 km derinliğin altında konumlanmış şekilde bulunurken uzak pürüzler ise 10 km derinliğin üzerinde konumlanmış haldedir. En büyük kayma genliği ve toplam salınan sismik moment sırasıyla 1.2 m ve 2.180 x1019 Nm olarak bulunmuştur. Doğalgaz sektöründe yüksek tüketime sahip şirketler (sanayi kuruluşları gibi) ve şehir dağıtım şirketleri yıl öncesinde aylık, yıl içinde de günlük tüketim talep tahminlerini bildirmekle yükümlüdür. Bu çalışma günlük ve aylık temelde orta vadeli doğalgaz talep tahminini tek değişkenli mevsimsellik içeren istatistiki yöntemler (zaman serileri ayrıştırılması, Holt-Winters üstel düzeltme, ARIMA/SARIMA) ile gerçekleştirmiştir. Bu tekniklerin ortak özelliği mevsimsellik içeren zaman serilerinde geçmiş bilgiyi barındıracak biçimde model kurmaları ve bir anda çok sayıda tahmine izin vermelerdir. Yapılan bu çalışmada günlük temelde 365 günlük, aylık temelde de 12 aylık tahmin bir anda gerçekleştirilmiştir. İstatistiksel olarak uygun tüm tahmin modellerinde, günlük temelde yıl öncesi doğalgaz tüketimini, 2014 yılı için en düşük hata, en yüksek uyum %24,6 MAPE ve 0,802 R2 değeri ile ARIMA(1,0,1)1(0,1,1)365 modelinde olmuştur. Bu modelin katsayıları istatistiksel olarak da anlamlı olup, kalıntıları beyaz gürültü olarak bulunmuştur. Aynı model aylık tahminlerde de en düşük hataya (MAPE) ve en yüksek uyuma (R2 ) sahip olduğu görülmüştür. Aylık tahminde, bu modelin MAPE ve R2 değeri sırasıyla %11,32 ve 0,981 olmuştur. Bu sonuçlar mevsimsel ARIMA modellerinin tek değişkenli teknikler arasında en uygun tahmin tekniği olduğunu göstermiştir. Bir anda çok sayıda tahmin yapılabilmesi ve sonuçlarının kabul edilebilir olması, bu tekniklerin yıl öncesinde aylık ve günlük tahminlerde kullanılabilmesine olanak tanımaktadır.In this study, the finite-fault rupture properties of the North Aegean Sea earthquake of 24 May 2014 have been_x000D_ investigated by inverting the teleseismic P and SH body waveforms. The inversion results indicated that the_x000D_ earthquake was due to failure of three asperities all of which were located in the NE of the hypocentre indicating_x000D_ unilateral fault rupture. The asperity closest to the hypocentre was located below the depth of 10 km while the_x000D_ distant asperities were located above the depth of 10 km. The maximum slip amplitude and total seismic moment_x000D_ release were found to be 1.2 m and 2.180 x1019 Nm, respectively.In this study, the finite-fault rupture properties of the North Aegean Sea earthquake of 24 May 2014 have been investigated by inverting the teleseismic P and SH body waveforms. The inversion results indicated that the earthquake was due to failure of three asperities all of which were located in the NE of the hypocentre indicating unilateral fault rupture. The asperity closest to the hypocentre was located below the depth of 10 km while the distant asperities were located above the depth of 10 km. The maximum slip amplitude and total seismic moment release were found to be 1.2 m and 2.180 x1019 Nm, respectively

New constraints on micro-seismicity and stress state in the western part of the North Anatolian Fault Zone : Observations from a dense seismic array

Major funding was provided by the UK Natural Environment Research Council (NERC) under grant NE/I028017/1 and partially supported by Boğaziçi University Research Fund (BAP) under grant 6922. We would like to thank all the project members from the University of Leeds, Boğaziçi University, Kandilli Observatory, Aberdeen University and Sakarya University. I would also like to thank Prof. Ali Pinar and Dr. Kıvanç Kekovalı for their valuable comments. Some of the figures were generated by GMT software (Wessel and Smith, 1995).Peer reviewedPostprin

The 2014 Earthquake Model of the Middle East: seismogenic sources

The Earthquake Model of Middle East (EMME) project was carried out between 2010 and 2014 to provide a harmonized seismic hazard assessment without country border limitations. The result covers eleven countries: Afghanistan, Armenia, Azerbaijan, Cyprus, Georgia, Iran, Jordan, Lebanon, Pakistan, Syria and Turkey, which span one of the seismically most active regions on Earth in response to complex interactions between four major tectonic plates i.e. Africa, Arabia, India and Eurasia. Destructive earthquakes with great loss of life and property are frequent within this region, as exemplified by the recent events of Izmit (Turkey, 1999), Bam (Iran, 2003), Kashmir (Pakistan, 2005), Van (Turkey, 2011), and Hindu Kush (Afghanistan, 2015). We summarize multidisciplinary data (seismicity, geology, and tectonics) compiled and used to characterize the spatial and temporal distribution of earthquakes over the investigated region. We describe the development process of the model including the delineation of seismogenic sources and the description of methods and parameters of earthquake recurrence models, all representing the current state of knowledge and practice in seismic hazard assessment. The resulting seismogenic source model includes seismic sources defined by geological evidence and active tectonic findings correlated with measured seismicity patterns. A total of 234 area sources fully cross-border-harmonized are combined with 778 seismically active faults along with background-smoothed seismicity. Recorded seismicity (both historical and instrumental) provides the input to estimate rates of earthquakes for area sources and background seismicity while geologic slip-rates are used to characterize fault-specific earthquake recurrences. Ultimately, alternative models of intrinsic uncertainties of data, procedures and models are considered when used for calculation of the seismic hazard. At variance to previous models of the EMME region, we provide a homogeneous seismic source model representing a consistent basis for the next generation of seismic hazard models within the region.Published3465-34966T. Studi di pericolosità sismica e da maremotoJCR Journa

23 October 2011 Van, Eastern Anatolia, earthquake (M (W) 7.1) and seismotectonics of Lake Van area

The 23 October 2011 Van earthquake took place in the NE part of Lake Van area, surprisingly on a fault (the Van fault) that is not present in the current active fault map of Turkey. However, occurrence of such a large magnitude earthquake in the area is not surprising regarding the historical seismicity of the region. The comparison of the damage patterns suggests that the earthquake is much likely a recurrence of the 1715 Van earthquake. The finite fault modelling of the earthquake using teleseismic broadband body waveforms has shown that the earthquake rupture was unilateral toward SW, was mostly reverse faulting, confined to below the depth of 5 km, did not propagate offshore, and was dominated by a failure of a single asperity with a peak slip of about 5.5 m. The total seismic moment calculated for the model is 4.6 x 10(19) Nm (M (W) a parts per thousand aEuro parts per thousand 7.1). The finite fault model coincides with the field observations indicating blind faulting and the vertical displacements over the free surface estimated from it correlate well with the maximum reported uplift along the coast of Lake Van above the hanging wall. The possible offshore continuations of the Van fault and some other faults lying its south are also discussed by assessing a previous offshore seismic reflection study and the earthquake epicentres and focal mechanisms

A teleseismic finite-fault rupture model for the August 17, 1999, izmit earthquake (Mw=7.6): implications for the seismic nucleation phase

A linear finite-fault inversion procedure is applied to teleseismically recorded broadband P and SH velocity waveforms of the August 17, 1999, izmit earthquake, to derive spatial and temporal distributions of the coseismic slip over the representative three-segment model fault. The model fault is longer than the mapped surface rupture, and it extends offshore for 25 km in the west, to define the western end of the earthquake rupture. The teleseismically derived slip model suggests a bilateral rupture with a total seismic moment release of 2.6 x 10(20) Nm, and that the rupture was dominated by failure of two major asperities with peak slip amplitudes reaching 7 m. The hypocentral area was represented by the relatively low displacement that separated the large asperities. In the west, the rupture reached the eastern entrance of the Cinarcik basin beneath the Sea of Marmara, with an average slip of ca. 2 m. This indicates that the rupture propagated offshore for ca. 20 km after crossing Hersek Peninsula. The analysis also reveals that the total rupture process time was 32 s, while the main seismic moment release, which corresponded to the rupture of the two large asperities, occurred between 4 s and 16 s after rupture initiation. The strong wave energy arrivals from the failure of the large asperities were preceded by weak wave arrivals in the initial section of the teleseismic waveforms used in this study. Along with some observations from previous studies, this emergent onset of the wave arrivals prompts us to discuss the possibility of a seismic nucleation process for this earthquake

New constraints on micro-seismicity and stress state in the western part of the North Anatolian Fault Zone: Observations from a dense seismic array

With the aim of extensively investigating the crustal structure beneath the western segment of the North Anatolian Fault Zone where it splays into northern and southern branches, a temporary seismic network (dense array for North Anatolia-DANA) consisting of 70 stations was deployed in early May 2012 and operated for 18 months in the Sakarya region during the FaultLab experiment. Out of 2437 events contaminated by explosions, we extracted 1371 well located earthquakes. The enhanced station coverage having a nominal station spacing of 7 km, lead to a minimum magnitude calculation of 0.1. Horizontal and vertical location uncertainties within the array do not exceed 0.8 km and 0.9 km, respectively. We observe considerable seismic activity along both branches of the fault where the depth of the seismogenic zone was mostly confined to 15 km. Using our current earthquake catalog we obtained a b-value of 1. We also mapped the b-value variation with depth and observed a gradual decrease. Furthermore, we determined the source parameters of 41 earthquakes with magnitudes greater than 1.8 using P-wave first motion polarity method. Regional Moment Tensor Inversion method was also applied to earthquakes with magnitudes greater than 3.0. Focal mechanism solutions confirm that Sakarya and its vicinity is stressed by a compressional regime showing a primarily oblique-slip motion character. Stress tensor analysis indicates that the maximum principal stress is aligned in WNW-ESE direction and the tensional axis is aligned in NNE-SSW direction. (C) 2015 Elsevier B.V. All rights reserved

Seismic behaviour of the North Anatolian Fault beneath the Sea of Marmara (NW Turkey): implications for earthquake recurrence times and future seismic hazard

Possible long-term seismic behaviour of the Northern strand of the North Anatolian Fault Zone, between western extreme of the 1999 A degrees zmit rupture and the Aegean Sea, after 400 AD is studied by examining the historical seismicity, the submarine fault mapping and the paleoseismological studies of the recent scientific efforts. The long-term seismic behaviour is discussed through two possible seismicity models devised from M (S) a parts per thousand yen 7.0 historical earthquakes. The estimated return period of years of the fault segments for M1 and M2 seismic models along with their standard deviations are as follows: F4 segment 255 +/- 60 and 258 +/- 12; F5 segment 258 +/- 60 and 258 +/- 53; F6 segment 258 +/- 60 and 258 +/- 53; F7 segment 286 +/- 103 and 286 +/- 90; F8 segment 286 +/- 90 and 286 +/- 36. As the latest ruptures on the submarine segments have been reported to be during the 1754-1766 earthquake sequence, and the 1912 mainshock rupture has been evidenced to extend almost all over the western part of the Sea of Marmara, our results imply imminent seismic hazard and, considering the mean recurrence time, a large earthquake to strike the eastern part of the Sea of Marmara in the next two decades