büyük istanbul depremi

ingilizce yapılmış bir çalışmayı buraya kopyalayayım. EARTHQUAKE HAZARD in ISTANBUL Mining Faculty – Geophysical Engineering ENGLISH 201 12 DECEMBER 2017 TOPIC OUTLINE EARTHQUAKE HAZARD in ISTANBUL Thesis: The expected major earthquake in Marmara Region constitutes a high risk in Istanbul and this risk and estimated losses can be anticipated by geological, geophysical and architectural analysis. I. Risk Analysis A.Geological B.Geophysical C.Architectural II. Losses A. Loss of Human Life B. Economical Loss C. Cultural Loss EARTHQUAKE HAZARD in ISTANBUL The earthquake hazard, especially in Istanbul, in recent years, has becoming an increasingly tense issue for people living in the Marmara region is an undeniable fact. Throughout history, the Marmara region in the north-west of Turkey experienced many destructive earthquakes. The most recent one is the Golcuk-based Kocaeli earthquake that highly affected the city of Istanbul, which took place in 1999. The earthquake studies that resulted after this tremendous disaster happened at Kocaeli, show that the next earthquake that is presently waiting for the Marmara region, will be based in Istanbul and include a high hazard level. The probability of having a Mw7+ earthquake is in the vicinity of 70% in the next 30 years (M.Erdik, M.Demircioglu, et al., 2004, pp. 605). The losses resulting from 1999 Kocaeli earthquake, reveal the priority of high-tech scientific studies for the Istanbul earthquake that is expected to happen in the future. Earthquake risk studies that are waiting for Istanbul are now being carried out in many government institutions such as municipalities, Mining Research and universities. The risk analysis studies consist of the knowledge of tectonics covering data about the fault on the Marmara region, the statistics of the past earthquakes, the hazard knowledge of the historical structures that have survived from the past and the data of recent settlements. Owing to the risk analysis studies, possible Istanbul earthquake scenarios are revealed. The expected major earthquake in Marmara Region constitutes a high risk in Istanbul and this risk and estimated losses can be anticipated by geological, geophysical and architectural analysis. Possible scenarios of the expected earthquake hazard in Istanbul may be revealed by geophysical, geological and architectural risk analysis studies within the Marmara region. For earthquake risk analysis scenario study, seismic zone is divided into cells by gridding process in Istanbul. The probabilistic seismic hazard analysis and deterministic earthquake hazard assessment approaches are used for this risk analysis. The probabilistic seismic hazard analysis, one of the two approaches mentioned above is a method that enables us to foresee all possible earthquake scenarios by evaluating the ground motion parameters like peak ground acceleration and spectral accelerations which give information about the ground. Another is the deterministic earthquake hazard assessment. It is fundamental to apply the probabilistic seismic hazard analysis method to evaluate the losses in the infrastructure systems of the city and emergency planning. This approach should be similar to this in Istanbul and the earthquake zone should be located on a specific fault in order to determine the earthquake scenario. This earthquake scenario forms the main line of the deterministic hazard assessment method, in which we have learned the history record of the time parameters of imitated ground motion. Hinged on the accessible geological and seismological information, the 'Credible Worst Case', which is associated with the intact parts of the Main Marmara Fault and has an earthquake magnitude of Mw = 7.5, was selected as the expected earthquake scenario (B.Siyahi, K.Sesetyan, et al., 2004, pp.615). The Marmara region has been a intersection between the east and the west for more than two thousand years. Historical earthquake records of Istanbul, which is a population-rich region throughout history and the capital of the Byzantine and Ottoman empires, are almost complete. The information obtained from the earthquakes recorded over two thousand years shows that there happens to be on average at least one medium-intensity (Io = VII-VIII) earthquake every 50 years in Istanbul. The average formation period of high-intensity (Io = VIII-IX) earthquakes is 300 years. The outcome of the scientists’ studies are that there is no earthquake that breaks the whole of the Main Marmara fault from the Gulf of Izmit to the Saros Gulf and the expected fault slip is calculated as 2.2 cm per year. It is claimed that the earthquake which occurred on 17.08.1999 , may be related to earthquake that happened in 1719. Assuming that the Marmara Sea stress regime did not change after 7.4 earthquakes in Kocaeli and 7.2 in Düzce, the recent studies show that it is about 65% ratio probability of happening 7.0 earthquake that will affect Istanbul (M.Demircioglu, M.Erdik, et al., 2004, pp.609-610). One of the application sites are architectural risk analysis that analysis and damage consideration studies are done. Two of the approaches for generating vulnerability relationships are essential. First of them depends on damage data obtained from field observations after an earthquake or from analysis. The first approach depends on the analysis of the structure with detailed time search or simplified methods, while the other one relates to damage data obtained from the field observations after an earthquake. The initial approach used in developing vulnerability estimates is also designated the experience data approach. The fact that particular constructed facilities’ economical classes have tendency to experience familiar characteristics and to participate identical destruction types in earthquakes is the experience data approach’s base point. Since they can just be used to calibrate the vulnerability relationships developed analytically, they play a crucial position in the fragility curve development study. When used to evaluate the risk of large portfolios of facilities, loss estimates which are made using this approach are more valid than concerning individual ones (Y.Fahjan, H.Akman, et al., 2003, pp. 10). Results show that, on the root of two independent methodologies (intensity-based and spectral displacement-based approaches), a sum of around 35,000 to 40,000 structures (about 5% of the total building stock) are evaluated to be harmed unrecoverable (complete damage). It is expected that the maximum loss will be in this damage group, particularly in a subset where the collapse will be of the worst "pancake" form. In buildings called pancake, floors after the earthquake stack on top of each other cause very challenging conditions for search and rescue. Estimated for pancaked structures will be in the region of 5,000 to 6,000. Additionally comes about show that around 70,000 structures will get broad harm and about 200,000 structures will be rather harmed (Y.Fahjan, H.Akman, et al., 2003, pp. 16). Work to be done for earthquake risk analysis should be fed with geological information. We need fault information of this region when we perform earthquake risk analysis for the Marmara region. The western part of the North Anatolian Fault Zone (NAFZ) controls the tectonic regime of the Marmara region. In the direction of Marmara Sea region (Mudurnu / Akyazı) west of 31.58E, NAFZ starts to lose its character of single fault line and becomes a complicated fault system.The extensive studies and new interpretations describe the tectonic evolution of the Marmara Sea region, defined as the overrunning of two different aged fault systems. These are Early Miocene-Early Pliocene Trakya-Eskişehir Fault Zone and its branches and Pliocene last Anatolian Fault and Branches. The northwest-southeast trending Trakya-Eskişehir fault is a large-scale strike-slip fault system active in the early Miocene-early Pliocene. At the end of the Late Pliocene, the North Anatolian Fault is divided into four parts. This event marks the beginning of the late neotectonic period. During this time, the KAF merged Ganos, Bandirma-Behramkale and Manyas-Edremit Fay Zones into a western eruption. These geological data of Marmara region including Istanbul also provide important information to be used in the risk studies for expected earthquake hazard. Risk analysis without geological information can not be expected to give correct results (E.Durukal, K.Sesetyan, et al., 2004, pp.607). Located in Europe and Asia both sides of Marmara Sea, Istanbul is one of the biggest cities in Turkey and the city has experienced high levels of earthquake ground motion. Intensity-based analytical methods can be used to estimate building damage and loss of life in urban areas in a possible earthquake. For estimating earthquake damages that may occur in Istanbul, the city building inventory was firstly extracted and classified according to the estimation of building damages. Population distribution related to building inventory was also obtained. Then, methods of predicting existing building damage and life loss were investigated and suitable methods and vulnerability relations were selected for the building structure of Istanbul. Vulnerability is defined as the degree of loss that will occur in a risk element or risk group if a predicted hazard occurs. The vulnerability of population, structures, subsystem systems and socio-economic structure are the main factors affecting the risk of earthquake and loss in urban areas. According to the deterministic approach, estimates made for Istanbul based on both intensity and spectral displacement show that the total of 3,500 to 5,000 buildings (0.4% of the total building) will suffer very badly. Beyond this, it is estimated that 20,000 to 30,000 buildings will suffer severe damage and 90,000 to 110,000 buildings will see moderate damage. In addition, the estimates of deaths vary from 15,000 to 35,000. The number of households that would need urgent housing is estimated to be approximately 500,000 (İBB Deprem ve Zemin İnceleme Müdürlüğü, İstanbul Olası Deprem Kayıp Tahminleri, 2009, p.249). Istanbul, the largest city of Turkey is thought to be one of the oldest metropolises, which has been the scene of uninterrupted urban settlement with its history spreading 2,600 years. When the 2000 years historical earthquake data of Istanbul is examined, it is seen that the city is affected by an average severity (Io = VII-VIII) every fifty years and a high severity (Io = VIII-IX) every 300 years. Important historic structures in the city were affected by these earthquakes in history. Fatih Mosque and Edirnekapı Mihrimah Sultan Mosque were constantly affected by the earthquakes. 78% of historical buildings in Istanbul are located in areas with high risk of earthquake violence. In the eventual anticipated Istanbul earthquake, these structures are very likely to be seriously damaged if the necessary measures are not taken in time. A numerical sensitivity study was carried out for the Egyptian obelisk in Istanbul to estimate the upper limit of the earthquakes that occurred in the provinces of Istanbul, and the numerical sensitivity supported by the shake table experiments showed that the obelisk, synthetic, which has stability under harmonic motion with frequency greater than 1.2Hz and amplitude less than 1g it is pointed out that the overthrowing can only occur in an earthquake of 7.6 magnitude and 5 km away from the earthquake. It is known that the obelisk is damaged in earthquakes of 869 and 1509. In the 869 earthquake, the sculpture said to have been on top of the obelisk is overturned (İBB Deprem ve Zemin İnceleme Müdürlüğü, İstanbul Olası Deprem Kayıp Tahminleri, 2009, p.215). During the Kocaeli earthquake of August 17, 1999, a series of historical buildings in Istanbul province, especially within the Fatih district, suffered various levels of damage. Within the scope of state earthquake projects, damage assessment of historical buildings in Istanbul was carried out. At the end of the project: The global risk level of the majority of the historical structures studied has been determined as medium-high or very high. However, the reliability level of evaluations made for the studied buildings is low, except for the large monumental structures which have already been studied analytically. The information obtained from the studies clearly demonstrates the necessity of strengthening the many historical and monumental structures in Istanbul against eartquake. Analyzes made as a result of possible earthquake scenarios show that the damage that will occur in Istanbul will create huge economic losses on the industrial, business and infrastructure systems. Damaged construction area in Istanbul is 64.3 million square meters in total. The cost of the damaged area is 399 Turkish Liras. The financial loss resulting from total structural damage is approximately 25,6 billion TL. The total financial losses (structural and non-structural) arising from building damage are obtained by multiplying structural damage by a factor of 1.5 to 2.0, according to research done for the US California region. In this case, the total financial losses (structural and non-structural) arising from building damages will be approximately 40 - 50 billion TL. This amount corresponds to approximately 5.000 TL per population to be affected in Istanbul. We estimate that other financial losses (infrastructure, work, tax, revenue losses) will be at least the total loss of the building after the earthquake. In this case, the total loss of Istanbul depremination will reach approximately 80-100 billion TL (İBB Deprem ve Zemin İnceleme Müdürlüğü, İstanbul Olası Deprem Kayıp Tahminleri, 2009, p.248). In another study, a deterministic earthquake risk scenario based on finite fault rupture models were applied for damage assessment and risk analysis in Istanbul Metropolis. This study aims to develop earthquake damage scenarios in terms of building damages and losses. Firstly, estimates of total building damage and death are carried out on the basis of different ground shaking scenarios for different hazard levels and at the same time including possible mitigation actions. The number of buildings expected to collapse in probabilistic hazard scenario is 23.291 (4.1% of total buildings in Istanbul) and the losses of life will be 31.521. In the deterministic scenario, the number of buildings expected to collapse and the number of casualties are doubled. The second important finding of this study is the effects of the work to be done to reduce the building damage and the casualties in Istanbul. These results clearly demonstrate the importance and influence of retrofit to reduce building damage and loss of life. Collapsed buildings, in case of a probabilistic hazard scenario, are decreased from 4.1% (23.291) to 0.26% (1471) and casualties from 31.521 to 2442. Also, casualties are decreased from 71.322 to 4729 for deterministic scenario (A.Ansal, V.Pessina, et al., 2008, p. 706-707). Consequently, geophysics, architectural and geological analyzes of earth sciences with developed technology are expected to contribute greatly to the risk assessment of Istanbul earthquake. This risk analysis is seen by creating predictive scenarios how the possible earthquake will affect Istanbul. As a result of these scenarios, life losses, economic losses and historical cultural losses in Istanbul metropolitan area can be calculated. These scientific analyses are based on the determinations of damages caused by Kocaeli earthquake in 1999, which was the last major earthquake that seriously affected the Marmara region, and earlier earthquakes. Moreover, with the help of the right consideration of the character of the North Anatolian Fault line, which is the source of the earthquakes in the region and the geological knowledge of the region; the analyses and the possible earthquake scenario to be created are supported with stronger bases. As a result of various risk analyzes, it is expected that the magnitude of the earthquake waiting for Istanbul is above 7 (Mw7 +) and it is expected to take place within the next 20 years. Under this high risk level, with favor of the eartquake scenarios that are created in consideration of Istanbul's infrastructure, urbanization and building damage detections, the severity of the earthquake scenarios can be clearly seen. It is anticipated that the expected earthquake will result in more than ten thousand buildings being destroyed over time and that more than 30 thousand people will lose their lives. Besides the loss of life, the economic and historical cultural loss of the city will also be very high. Istanbul's transportation, infrastructure points, construction and damage to the workplace based on the structure of the country's economy is estimated to be around 40 billion pounds in the calculation. In many places, especially the Fatih district, many historical buildings will be damaged, and it is no doubt foreseen that there will be great losses in terms of the cultural heritage of the country. As demonstrated by the analysis and the results obtained, state authorities should take the necessary precautions against the possible earthquake in Istanbul. In the absence of any necessary measures, it is now evident that there will be severe damage to the citizens in Istanbul and the whole country. Figure 1. The long-term seismicity of the Marmara region Fig 2. Mw = 7.5 scenario earthquake for the Marmara region References - M.Erdik, N.Aydinoglu, Y. Fahjan, K. Sesetyan, M. Demircioglu, B. Siyahi, E. Durukal, C. Ozbey, Y. Biro, H. Akman and O. Yuzugullu, Earthquake risk assessment for Istanbul metropolitan area, Boğazici University, Kandilli Observatory and Earthquake Research Institute, Department of Earthquake Engineering, Istanbul, Turkey, June 2003 - M. Erdik*, M. Demircioglu, K. Sesetyan, E. Durukal, B. Siyahi, Earthquake hazard in Marmara Region, Turkey Department of Earthquake Engineering, Kandilli Observatory and Earthquake Research Institute, Bogazici University, Istanbul, Turkey, April 2004, 605-631 - T.C Istanbul Buyuk Sehir Belediyesi Deprem Risk Yonetimi ve Kentsel Iyileştirme Daire Başkanlığı Deprem ve Zemin Inceleme Mudurlugu, Istanbul Olası Deprem Kayıp Tahminleri, Istanbul, Turkey, October 2009 - A. Ansal, A. Akinci, G. Cultrera, M. Erdik, V. Pessina, G. Tönük, G. Ameri, Loss estimation in Istanbul based on deterministic earthquake scenarios of the Marmara Sea region (Turkey), In Soil Dynamics and Earthquake Engineering, Volume 29, Issue 4, 2009, Pages 699-709, ISSN 0267-7261 Figures 1- M. Erdik*, M. Demircioglu, K. Sesetyan, E. Durukal, B. Siyahi, Earthquake hazard in Marmara Region, Turkey Department of Earthquake Engineering, Kandilli Observatory and Earthquake Research Institute, Bogazici University, Istanbul, Turkey, April 2004, 605-631 2- M. Erdik*, M. Demircioglu, K. Sesetyan, E. Durukal, B. Siyahi, Earthquake hazard in Marmara Region, Turkey Department of Earthquake Engineering, Kandilli Observatory and Earthquake Research Institute, Bogazici University, Istanbul, Turkey, April 2004, 605-631