(FUZZY LOGIC AND APLLICATIONS IN GEOPHYSICS: A SEISMOLOGY EXAMPLE

Bulanık mantık, teknolojinin de etkisiyle son yıllarda birçok problemin çözümünde yaygın olarak kullanılan yöntemlerden biridir. Doğada kesin olarak tanımlanamayan birçok olayın bulanık mantık yardımıyla çözümleri mümkün hale gelmiştir. Uygulama alanının geniş olması ve birçok problemin çözümünde başarılı sonuçların elde edilmesi bu yönteme olan ilgiyi arttırmıştır.Bulanık mantığın jeofizik alanındaki uygulamaları da giderek artmaktadır. Özellikle sismik, elektromanyetik ve özdirenç gibi yöntemlerin ters çözümünde ayrıca parametre tayini ve ön kestirim gibi uygulamalarda kullanılmaktadır. Bu çalışmada bulanık mantığın günümüze kadar olan jeofizik uygulamaları derlenmiş ve yaygın olarak kullanım amaçları özetlenmeye çalışılmıştır. Batı Anadolu deprem katalog verilerinin Uyarlanabilir Yapay Sinir-Bulanık Mantık Çıkarım Sistemi (Adaptive Neurofuzzy Inference System) (UYBÇS) ile değerlendirilmesi üzerine örnek bir çalışmaya yer verilmiştir. With the effect of advancing technology, Fuzzy logic has become one of the most common methods used in solving problems during the recent years. Solutions of the many ill defined/unidentified events in nature/earth are made possible by means of fuzzy logic. Wide ranges of applications and obtaining successful results are caused the increasing interest on this method.Applications of Fuzzy logic on Geophysics are also increasing day by day. It is used on particularly inversion of seismic, electromagnetic and resistivity data, prediction of some physical parameters and estimation studies. The aim of this study is to compile the articles which are about Fuzzy logic application on geophysics and to summarize its intended purpose. Analyzing of the Earthquake data of Western Anatolia Using with Adaptive Neurofuzzy Inference System, is given an example of this method as a seismological application

SELF POTENTIAL AND GRAVITY STUDIES IN THE SEFERIHISAR GEOTHERMAL FIELD

Seferihisar jeotermal alanı İzmir-Ankara melanjının GD'sunda, İzmir ilinin yaklaşık 40 km GB'sında yer almaktadır. Bölgenin temelini Menderes masifine ait Paleozoik yaşlı kristalin şistler oluşturur. Bölgedeki tektonik oluşumlar KD-GB doğrultulu fay ve kırıklar ile bunları diyagonal kesen faylardan oluşmaktadır. Bölgede sıcak su çıkışları ise KD-GB yönde uzanan faylar boyunca görülmektedir. Alandaki önemli jeotermal çıkışlar; Tuzla ılıcası, Cumalı kaplıcası, Doğanbey kaplıcası ve Karakoç kaplıcası civarında gözlenmektedir. Bölgede daha önce yapılan yer elektrik araştırmalarının sonuçları, sıcak su kaynakları ve volkanik domlar civarında gözlenen düşük özdirenç değerlerinin alanın ana tektonik yapısına paralel olarak GB-KD yönünde uzandığını ortaya koymuştur. Bouguer gravite verilerine uygulanan ters çözüm işlemi sonucunda; metamorfik taban derinliği, 1.6-1.7 km olarak saptanmıştır. Doğal gerilim belirtileri ise, genelde jeolojik haritalarda belirtilen ve sıcak suyu yüzeye taşıdığı düşünülen faylar boyunca ortaya çıkmaktadır. Doğal gerilim çalışmaları sonucunda alandan elde edilen türevsel doğal gerilim belirtileri, genelde Tuzla-Cumalı arasında bulunan bölgede yoğunlaşmaktadır ve taşıyıcı fayların bulunduğu yerlerde daha belirgin olarak ortaya çıkmaktadır. Doğal gerilim belirtilerinin değerlendirmeleri sonucunda, Tuzla fayının bulunduğu yerde odak derinliği yaklaşık olarak 500 m saptanırken, Karakoç kaplıcasına yakın diğer bir noktada odak derinliği 450 m olarak bulunmuştur. Ayrıca, uçlaşma odaklarının Tuzla-Karakoç ve Cumalı kaplıcaları arasında yoğunluk göstermesi, jeolojik ve diğer jeofizik bulgularla uyumlu bir sonuç vermiştir. Seferihisar geothermal area located in the SE of İzmir-Ankara melange is approximately 40 km in the SW of the city of İzmir, Turkey. The basement of the study area is consist of the crystalline rocks of the Menderes Massif of Paleozoic age. The main tectonic features are faults and fractures extending in NE-SW direction. These features are transversed by the secondary (relatively younger) faults striking NW-SE diagonally. Hot water springs which are observed around Tuzla, Cumalı, Doğanbey and Karakoç, appear along the faults. The result of resistivity measurements indicates that the low resistivity values located near and around the hot springs and volcanic domes are extended in the direction of SE-NW which is parallel to the major tectonic structure of the area. Using the Bouger gravity data, the depth of the metamorphic basement was estimated as 1.6-1.7 km. The self potential anomalies are generally observed along the faults transporting the hot water to the surface and indicated by the geological maps. The self potential gradient anomalies are localized between the Tuzla and Cumalı geothermal areas and originated by the transporting faults. After the interpretation the focal depths are approximately 500 m for the Tuzla fault and approximately 450 m around the Karakoç hot spring. Furthermore, polarization foci are intensively observed between the Tuzla-Karakoç and Cumalı areas and this is in accordance with geological and geophysical evidences

Examination of the kinematic structures in İzmir (Western Anatolia) with repeated GPS observations (2009, 2010 and 2011)

The Western Anatolia and the Aegean Sea regions are one of the most significant seismically active and rapidly deforming fields in the world. Generally, seismic activities cause deformations and these deformations are monitored with Global Positioning System (GPS) /Global Navigation System (GNSS). In this context, GPS data were used to determine the deformation of İzmir and its surrounding to estimate the relative plate motions. In this study, the kinematic structures of the faults, which control the seismic hazard in İzmir and its surroundings, processing results of the three-year (2009, 2010 and 2011) episodic GPS observations and the estimation of displacements for 21 GPS stations were presented. The aim of this study is to examine interplate motion of the stations and their relations with the tectonic structures, seismicity and paleomagnetism and additionally, to interprete the motions of the study area relative to different block motions. Consequently, the mean motion of the study area was found approximately 25 mm/yr (towards the SSW) in the Eurasia fixed frame solution. The Aegean block fixed frame and the Anatolian block fixed frame solutions were computed relative to Euler vectors. In Aegean and Anatolian block solutions it was determined that the stations move separately, not as a group. In Euler pole solution, some stations are separated from each other and meanwhile some stations are grouped by considering the differences and similarities of the station motions. According to this solution three lines and two regions were described in the study area. The relations between seismicity and paleomagnetic studies and the kinematic structures determined in Anatolian block fixed frame and Euler pole solution were also investigated. When the Anatolian block fixed frame solution and the earthquakes occurred between the years 1973 and 2011 were evaluated together, it was found that in the high seismically active region especially near to Sığacık bay, the motions of GPS stations were different even though their locations were close to each other. As a result of this, the relationship between the vector directions and active tectonism was determined. Additionally, in the Euler pole solution directions of the motion were found to be coherent with the paleomagnetic results, particularly in Urla and its surroundings. Here, the block fixed frame and Euler pole solutions and additionally, relations of them with seismicity and tectonism were mentioned as difference from previous studies. Besides, in this study, high importance was given to locate each station in main geological formations of the study area. Keywords: GPS/GNSS; Western Anatolia; Izmir; Tectonic feature

Determination of structure parameters on gravity method by using radial basis functions networks case study: Seferihisar geothermal area (western turkey)

Summary: Artificial Neural Networks (ANN) have been used in a variety of problems in the fields of science and engineering. Applications of ANN to the geophysical problems have increased within the last decade. Especially it has been used to solve inversion problems such as seismic, electromagnetic, resistivity. Also there are some other applications such as parameter estimation, prediction and classification. In this study, Radial Basis Function Networks (RBF NN) were applied to theoretical gravity data and Seferihisar gravity data to investigate the applicability and performance of this network for gravity method. Seferihisar is one of the important geothermal areas in the Western Turkey. There are many geological and geophysical studies in this area. Bouguer gravity data were analyzed by RBF NN to estimate depth and density contrast of the structure. Also the RBF NN results were compared with the results of a previous study