Deprem tehlikesi altındaki bölgelerin analitik hiyerarşi yöntemi ile risk durumunun belirlenmesi: Bahçelievler örneği
Determining the risk status of regions under earthquake danger by analytical hierarchy process: Bahçelievler example
Yazar: ORHUN BİÇER
Danışman: PROF. DR. ZAİDE DURAN
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Geomatik Mühendisliği Ana Bilim Dalı / Geomatik Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2022
Konu: Jeodezi ve Fotogrametri = Geodesy and Photogrammetry
Dizin: Analitik hiyerarşi yöntemi = Analytical hierarchy method ; Coğrafi bilgi sistemleri = Geographical information systems ; Deprem = Earthquake ; Çok kriterli karar verme = Multi criteria decision making

Özet:
İş ve sosyal imkanların daha fazla olduğu şehirler insanları kendisine her geçen gün daha fazla çekmektedir. Şehirlerde hızla artan nüfusa paralel olarak ortaya çıkan sorunlar çoğalmaktadır. Çarpık ve plansız büyüyen şehirlerde, altyapı problemleri yaşanmakta, mühendislik hizmeti almadan inşa edilen yapı sayısı artmaktadır. Tarihin ilk çağlarından beri insan yaşamını tehdit eden doğal afetlerin yıkıcı etkisi, şehir alanları için günden güne daha tehlikeli bir hal almaktadır. Şüphesiz ki günümüzde şehirlerin ve şehirlerde yaşayan insanların önündeki en büyük sorunlardan bir tanesi deprem gerçeğidir. İnsan hayatını günden güne daha fazla tehdit eden depremin yaratacağı olumsuz etkiler biran önce belirlenmeli ve insan hayatının korunabilmesi için gerekli tedbirler alınmalıdır.
Gelişen teknolojiyle beraber, deprem gibi doğal afetlerin yarattığı risklerin belirlenmesi kolaylaşmış ve tedbirlerin biran önce alınabilmesi imkanı doğmuştur. Günümüzde insanoğlunun elinde, deprem riskinin belirlenmesi yardımcı olacak çeşitli donanımlar, yazılımlar ve yöntemler mevcuttur. Mekansal olarak analiz yapmaya olanak tanıyan Coğrafi Bilgi Sistemleri (CBS), karar vermede kullanıcılara amaçları doğrultusunda yardımcı olmaktadır. Farklı kriterlerin birlikte değerlendirilmesine ve farklı yöntemlerin birarada kullanılmasına imkan tanıyan CBS, deprem riskinin belirlenmesi için güçlü bir araçtır.
Deprem riskinin ortaya çıkmasını farklı kriterler etkilemektedir. Bu kriterler kendi aralarında sınıflandırılmalı, etki miktarları belirlenmeli ve değerlendirmeler buna göre yapılmalıdır. Analitik Hiyerarşi Yöntemi (AHY), farklı kriterlerin ikili olarak değerlendirilmesinde ve kriterler arasındaki önceliklerin belirlenmesinde kullanılan Çok Ölçütlü Karar Verme (ÇÖKV) yöntemlerindendir. 
İstanbul tarih boyunca, büyük depremlerden etkilenmiş kadim bir şehirdir. Bu tez çalışmasında, İstanbul İli Avrupa Yakası'nda bulunan Bahçelievler İlçesi için AHY kullanılarak CBS tabanlı deprem risk analizi yapılmıştır. İlçenin deprem riski, alansal olarak değerlendirilmiştir. Çalışmada kullanılan veriler açık kaynaklardan, kamu kuruluşlarından ve kamu kuruluşlarının yayınlarından elde edilerek CBS ortamında işlenmiştir. Değerlendirmeler yapılırken kriterler, geoteknik hasar görebilirlik, yapısal hasar görebilirlik ve sosyal hasar görebilirliğin belirlenmesinde kullanılmıştır. Bütün kriterler AHY kullanılarak ağırlıklandırılmıştır. Geoteknik hasar görebilirliğin belirlenmesi için eğim, jeoloji, heyelan ve sıvılaşma kriterleri kullanılmıştır. Yapısal hasar görebilirliğin belirlenmesinde binaların içinden toplanan verilerden elde edilen sonuçlar kullanılmıştır. Sosyal hasar görebilirlik değerlendirilirken kullanılan kriterler ise nüfus yoğunluğu, ulaşım, önemli tesisler ve toplanma alanlarıdır. Geoteknik hasar görebilirlik, yapısal hasar görebilirlik ve sosyal hasar görebilirlik haritaları, AHY ile belirlenen ağırlıklardan yararlanarak CBS ortamında üst üste bindirilmiş ve Bahçelievler İlçesi'ne ait deprem risk haritası oluşturulmuştur. 
AHY kullanarak CBS ortamında yapılan çalışmalar sonucunda elde edilen verilere göre hazırlanan ilçeye ait deprem risk haritası 5 sınıfa ayrılmıştır. Çalışma alanının, 0,03 km2'sinin çok düşük risk sınıfında, 1,45 km2'sinin düşük risk sınıfında, 8,60 km2'sinin orta risk sınıfında, 5,48 km2'sinin yüksek risk sınıfında, 1,13 km2'sinin ise çok yüksek risk sınıfında olduğu tespit edilmiştir. Sonuçlar, çalışmada kullanılan kriterler ile karşılaştırılmış ve deprem risk sınıflarının oluşmasına etki eden kriterlerle ilgili değerlendirmeler yapılmıştır.

Abstract:
Throught the ages, people who have found ways to protect themselves from natural disasters such as eartquakes, floods, lanslides, volcanic eruptions and so on have lived in harmony with nature. In the early ages, the human who adopted hunter-gatherer lifestyle started build colonies on the waterside with increased knowledge and first towns emerged. With the Industrial Revolation, large settlements emerged, and with increasing migration to these settlements, the population icreased rapidly. Today, migration to urban areas from rural areas continues due to high economic and social opportunities. In parallel with the migration and rapid population growth in cities, many problems occur. In the cities which grow unplanned, infrastracture problems are experienced, and the number of structures built without benefiting from engineering services is increasing.
One of the dangers facing the cities where millions of people lives is natural disasters. One of the natural disaster that threaten the lives of people living in cities and cities is an earthquakes. Cities built on fault lines or near fault lines are at risk. Earthquakes cause loss of life and property, as well as economic losses. İt is an inevitable obligation to determine risk areas in cities under the earthquake risk and to take precautions to ensure the continuation of human life.
Geographic Information System (GIS) used for storage, processing, analyzing, presenting data, etc. GIS is used in many different fields such as determining urban and rural areas, showing the lithological structure, making population analysis, determining the areas where communication towers will be built, and analyzing transportation networks, etc. by many different branches such as geomatic engineering, city planning, geological engineering, comminication engineeing, etc. GIS is also very useful for earthquake risk analysis, as it offers spatial analysis. GIS also allows the use of different methods and combined evaluaion of many criteria. Many different criteria affect the occurence of earthquakes. It is necessary to assess these criteria and determine their impact on the risk of earthquakes. For these reasons, GIS is an effective, fast inexpensive tool for determinin the risk of earthquakes.
The risk of an earthquake affects more than one criteria. These criteria must be assessed and their effects on the occurrence of earthquake risk should be investigated. In studies where many criteria are effective, these criteria must be assessed within the framework of certain rules in order to make evaluations. The Analytic Hierarchy Process (AHY), a Multi-Criteria Decision Making (MCDM) method, is a effective method for assessing different criteria. AHP is a method, based on pairwise comparisons, enabling the determination of the priorities of the criteria which developed by T.L. Saaty in the 1970s. The criteria are assigned values from 1 (least important) to 9 (most important) based on the amount of importance and the weiahts of the criteria are determined. In addition, AHP allows the use of qualitative and quantitative observations together. AHP is widely used in different areas with different purposes, such as performing cost-benefit analysis, chosing the most appropriate location for the establishment of a facility, detemining the most suitable supplier, identifying the most appropriate road network, etc. Furthermore, AHP is widely used to conduct earthquake risk analysis as it offers the opportunity to combine different criteria and include qualitative and quantitative judgments in assessments.
Istanbul, which was the capital of Roman, Byzantina and Ottoman Empires, is most populous city of Turkey. In addition, Istanbul is Turkey's leading city in many areas, such as culture, trade, tourism, health and so on. Istanbul located in a region close to the Northern Anatolian Fault Line, has been affected by major earthquakes throughtout history. As a result of some of these earthquakes, even the tsunami was formed, and a lot of lives were lost. The earthquakes that occured in Kocaeli and Düzce in 1999 have once again revealed how fascinating the city of Istanbul facing. In Istanbul, where about 16.000.000 people live, the risk of earthquakes must be determined, and precautions must be taken to prevent economic losses as well as ensuring life and property safety.
In this thesis study, an earthquake risk analysis based on GIS was conducted using AHP for Bahçelievler District loceted on the Istanbul Province Europian side. Bahçelievler, the 5th most populous district of Istanbul with 605.300 people, was built on 16,69 km2. Although, studies has been carried out to determine the risk of earthquake on the scale of Istanbul province or other districts, the number of studies on the Bahçelievler scale is limited. 
There are many criteria that affect the risk of earthquake. In the study, the criteria used to conduct earthquake risk analysis were obtained from open sources, public institutions and publications of public institutions. The criteria affecting the earthquake risk are grouped among themselves. The collected data were digitized and edited in GIS enviroment. Using AHP, the weights of each criteria and group of criteria are determined. The determined weights were processed into relevant criteria in GIS enviroment. 
Three main groups have been established to determine the earthquake risk. These are geotechnical vulnerability, structural vulnerability and social vulnerability. Geotechnical vulnerability is directly related to topography. The second level of criteria for determining geotechnical vulnerability, slope landslide, geology and liquefaction. These criteria are divided into sub-criteria according to the conditions in district. The weight of each relevant criteria was determined and processed into the GIS enviroment, and maps were created for each criterion. These maps are also overlapped into the GIS enviroment for creating geotechnical vulnerability maps.
Determination of structural vulnerability is an essential element for earthquake risk analysis, since ensuring the continuation of human life is important in the event of an earthquake. The building risk level was used to determine structural vulnerability. The building risk level has been obtained from the results of the building inspection study with a quick scan conducted by Istanbul Metropolitan Municipality. The work determines the risk level of buildings as a result of the data collected from inside the building and predicts what percentage of ground acceleration is expected to effect the building at its location. Results are evaluated in 5 classes. The weights of building risk level groups were determined using AHP and a structural damage map was created.
The emergence of enviromental and social problems as a result of rapid and unplanned urbanization increases the importance of identifying social vulnerability in earthquake risk analysis. In the study, population density, transportation, important facilities and gathering areas were used as criteria to determine social vulnerability. Each criteria is divided into its own sub-criteria group and weights determined using AHP are processed in GIS. The social vulnerability map was created by overlapping the maps created for the second level criterias.
An earthquake risk map of Bahçelievler district of Istanbul was obtained as a result of the overlapping geotechnical vulnerability, structural vulnerability and social vulnerability maps using the weights of the criteria. The study result has been assessed in 5 classes, very high risk, high risk, medium risk, low risk and very low risk. It has been determined that 0,03 km2 of Bahçelievler district has a very low earthquake risk, 1,45 km2 has a low earthquake risk, 8,60 km2 has a medium earthquake risk, 5,48 km2 has a high earthquake risk, and 1,13 km2 has a very high earthquake risk. It has been determined that the high and very high earthquake risk areas of the district are generally with high population density and the danger of landslide and liquefaction. 
This study will provide managers with the opportunity to take precautions in areas that are at risk of earthquake. In a city like Istanbul, where the danger of earthquakes is high, it is difficult to work in every region at the same time against earthquakes. Another benefit of this study is that areas that are at risk of earthquakes are classified. With this classification, the areas that need to be precautionary can be queued. Due to the precautions to be taken, the loos of life and property will be minimized, while economic losses will also be avoided.