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On February 6th, 2023, earthquakes with magnitudes of 7.7 and 7.6 on the Richter scaleoccurred in Pazarcik/Kahramanmaras and Elbistan/Kahramanmaras/Turkey, respectively, withdepths of 9 km and 7 km and at UTC times of 01:17 and 11:24. These earthquakes causedsignificant loss of life and property in Eastern Turkey and Northern Syria. The district of Golbasiin the province of Adiyaman was one of the areas highly affected by the earthquakes due toboth the bearing capacity loss of the soil and the location of the Pazarcik Segment of theEastern Anatolian Fault Zone passing through the district center. Two days after theearthquake, the earthquake research and application center team from Dokuz Eylul Universityconducted preliminary field observations in the region. Structural damage in Golbasi wasobserved to be the result of soil-bearing capacity losses and possible liquefaction. It is knownthat the ground in Golbasi is composed of ancient lake sediments. It is considered that sitesoils in the region has caused significant soil amplification if they are highly plastic whereaslarge deformations and dependent attenuation took place in low plastic clays with silt.Therefore, it is essential to determine shear-wave velocity distribution as part of this study,microtremor measurements were taken at a total of 32 points with a 300 m sampling intervalin the Golbasi district to establish an initial database that could be easily extended by furthermeasurements to be made in intermediate locations. As a result of the microtremormeasurements, the predominant vibration period of the region, the Kg damage indexparameter, and the shear wave velocity models in 1, 2, and 3 dimensions via a forward andinverse solution of the HVSR curves were calculated, and presented.

On October 30, 2020, an earthquake with a magnitude of MW = 6.6 occurred due to the rupture of 30 to 40 kmof a normal fault in east-west direction which is approximately 12 km far away from Samos Island, Greece.During this earthquake, Bayraklı district of the city of Izmir, Turkey, which is 70 km to the epicenter, wasseverely affected despite its far location. In the scope of this study, preliminary assessment of geotechnicalaspects and structural damage which occurred in Manavkuyu neighbourhood of Bayraklı district is conducted.In this context, spectral characteristics of strong ground motion and local site effects such as soil amplification,resonance and soil nonlinearity are investigated. It is revealed that a significant amplification of rockacceleration occured due to soft and deep soil layers in the study area. Although the basin effect is consideredto strongly contribute to soil amplification, its assessment is left for further studies. Considerable amount ofsoil nonlinearity is both observed from strong motion records and effective stress based seismic responseanalysis. Finally, the observed structural damages are discussed considering aforementioned aspects.

Samos Earthquake(30.10.2020, Mw =6.9) had catastrophic effects on theBayraklı district (withinBornova Plain) of Izmir. 17 buildings completely collapsed, almost thousand building were heavily damaged due to the earthquake.Bornova Plain isan east-west trending tectonic depression developed within thehorst-graben system ofWestern Anatolia. TheBornova Plain was filled with the alluvium brought by the short, seasonal streams that reach the plain from the surrounding high masses. Seasonal changes in the flow regimes of these streams have created an inhomogeneous accumulation in horizontal and vertical directions. This thick accumulation of low S-wave velocity and intensity will amplify the earthquake waves. However, it should be noted that the basin topography of the plain will also have unwanted effects on earthquake waves.3513 strong ground motion station located in theBayraklı district and on the coast of Izmir Bay measured the peak acceleration value(PGA) of the earthquake as0.108 g. Although the building stock ofİzmir does not differ from place to place, various analyzes have been made in the areas where the buildings collapsed after the earthquake was located to investigate the reasons for the collecting of demolitions in asingle area. In this context, an earthquake simulation was carried out for the soil under a collapsed building. In designing this earthquake simulation; Earthquake dataof 3513 strong-motion station, soil-bedrockmodel of 3513 strong-motion station, soil-bedrockmodel of a collapsed building were used. For this analysis, the soil-bedrockmodel under the collapsed building was created by the inverse solution of single-point microtremor measurement. In summary, the study was carried out by deconvolved the 3513strong-motion station earthquake datato the bedrock interface located under the station and transferring this transported datafrom the bedrock interface under the collapsed building to the soil layers and the ground surface. According to the findings obtained from this process, the soil under the collapsed building amplified the earthquake waves more than 2 times. Also, dynamic soil behavior during the earthquake moved away from linear behavior and showed non-linear behavior from an average depth of55-60 m.

In this study, the distribution of dynamic amplification factor (DAF) values at the study area were obtained by joint evaluation of scenario earthquake parameters that could occur in the study area with single station microtremor data gathered at 112 points. The dynamic amplification factor can also be defined as the ratio of the magnitude of earthquake waves from the bedrock to the ground. Also the DAF value is a parameter that represents the entire spectrum, not a single peak value. The data collected by using single station microtremor method were evaluated by horizontal to vertical spectral ratio (HVSR) technique. The scope of the study is the common interpretation of predominant soil period (PSP), dynamic amplification factor, geology data and topography data of the research area. Dynamic amplification factor values are obtained generally higher than 2 at regions near the sea level that composed of alluvial units. Dynamic amplification factor values which are lower than 2 were obtained at the volcanic rocks located at high elevations. As expected, predominant soil period values are distributed in directly proportional to the dynamic amplification factor at the study area. The smallest amplification value in the study area is 1.20, while the maximum magnification value is around 3. The coincidence of the maximum values of predominant soil period and dynamic amplification factor with the alluvial units where the elevation is low shows that these parameters were obtained in harmony with each other.

Deprem-zemin ortak davranışıtanımlanırken zemin-anakaya modelleri temel alınmaktadır. Zemin anakayatanımlamalarında kayma dalgası hızı (Vs) kullanılır. Vs< 760 m/s durumundaortam zemin; 760 m/s3000 m/s durumunda ortam sismik anakaya olarak tanımlanır. Buçalışmada, İzmir iç körfezi doğusunda yeralan Bornova ovasında 2-B zemin,mühendislik ve sismik anakaya modellerinin oluşturulması için mikrogravite veaktif-pasif kaynaklı yüzey dalgası yöntemleri kullanılmıştır. Bu çalışma temelolarak üç aşamadan oluşmaktadır; 1) Yüzey dalgası yöntemleri kullanılaraksismik hızların elde edilmesi, 2) Elde edilen sismik hızlardan ampirikbağıntılar yardımıyla yoğunluk değerlerinin hesaplanması, 3) Mikrograviteyönteminden elde edilen rezidüel gravite değerlerinin bu yoğunluk değişimlerinegöre modellenerek 2-B zemin- anakaya modellerinin oluşturulmasıdır. Elde edilenmodeller incelendiğinde özellikle körfeze yakın kesimlerde zeminin 300-400 mkalınlığında ve birbirinden farklı fiziksel özelliklere (S- Dalga hızı,yoğunluk) sahip tabakalardan oluştuğu saptanmıştır. Zemin kalınlığınınkuzey-güney yönünde değiştiği gözlemlenmiştir.

Deprem-zemin ortak davranışı tanımlanırken temel alınan 2B'lu zemin-anakaya modellerinin oluşturulmasıamacıyla İzmir Körfezi doğusunda 10 km uzunluğundaki K-G doğrultulu 2 profil boyunca çeşitli jeofizikyöntemler uygulanmıştır. 50 m derinliğe kadar olan Kayma dalgası hız (Vs) değerleri MASW ve ReMiyöntemlerinin birlikte kullanılması ile elde edilmiştir. Daha derin Vs değerleri ise SPAC yöntemi kullanılmıştır.Elde Edilen Vs değerlerinden ampirik bağıntılar yardımıyla tabakaların yoğunluk değerleri hesaplanmıştır.Mikrogravite yönteminden elde edilen residüel gravite değerleri bu yoğunluk değişimlerine göre modellenerek2B’lu zemin- anakaya modelleri oluşturulmuştur. Elde edilen modeller incelendiğinde özellikle körfeze yakınkesimlerde zeminin 300-400 m kalınlığında ve birden fazla tabakadan oluştuğu saptanmıştır. Zemin kalınlığınınKörfez doğusuna ve Kuzey-Güney yönüne doğru azaldığı belirlenmiştir.