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- ArticleYalnız künye2026Three dimensional shear wave velocity (Vs) structure and dynamic soil properties of Adıyaman-Gölbaşı basin using HVSR and SPAC methods
Pamuk, Eren; Fırat, Seyhan; Büyüksaraç, Aydın; Çetin, Kemal Önder; Bektaş, Özcan; Işık, Nihat Sinan; Sarıtepe, Halil Erdim
On February 6, 2023, two devastating earthquakes (Mw 7.8 and Mw 7.6) struck southeastern Türkiye, two of the most destructive seismic events in the country's history. This study investigates the structural damage and seismic vulnerability in the Gölbaşı Basin, located in Adıyaman Province—one of the regions most severely affected by these events. Geophysical techniques, the HVSR (Nakamura) and spatial autocorrelation (SPAC) methods, were employed to develop shear wave velocity (Vs) profiles and evaluate the dynamic soil properties of the basin. Shear wave velocities within the Gölbaşı Basin, down to a depth of 300 m, range from 211 to 923 m/s, with the lowest values observed near the lake, indicating weak and loose soil conditions. Natural site periods vary between 0.1 s and 2.86 s, with the longest periods (T > 2.5 s) also concentrated in the vicinity of the lake. In areas where the engineering bedrock (Vs > 760 m/s) lies deeper than 250 m, natural periods frequently exceed 1.5 s. These findings suggest that zones with thick alluvial deposits and low Vs values are particularly susceptible to seismic hazards. Structural damage was most severe in areas where Vs is below 350 m/s, site periods exceed 1 s, and the engineering bedrock lies deeper than 50 m. Notably, low-rise industrial buildings and low-rise structures with basement floors remained intact despite poor soil conditions. In contrast, in areas with more competent ground conditions, structural collapses were more likely caused by deficiencies in engineering design or construction quality.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2025Geothermal gradients and seismicity correlations in the Biga Peninsula (NW Türkiye) based on Curie point depths
Büyüksaraç, Aydın; Bektaş, Özcan; Pamuk, Eren; Canbaz, Oktay
The Biga Peninsula has hot springs with geothermal temperatures varying between 40oC and 175oC. In this study, we investigate the regional temperature distribution and change in radiogenic heat production in the Biga Peninsula. We use EMAG2 magnetic data to estimate the Curie point depth (CPD). Our findings show that the CPD in the region varies between 9 km and 17 km. We also calculated the geothermal gradient and heat flow values based on the CPD data. which range between 92.9 and 141.6 mWm-2. Additionally, we also obtained values for zo, zt, and zb from the power spectrum and calculated 1D geothermal gradient change for examined blocks. The resulting equations are: zt = z80°C, zo = z350°C, and zb = z580°C. These equations enabled us to propose a new formula to calculate the CPD. We also obtained the Conrad discontinuity depth (zc = z680°C) in the Biga Peninsula. Furthermore, we prepared 2D heat flow and temperature profiles along three sections to investigate the relationship between heat changes and earthquake focal distributions. The results indicate that seismicity is high in the southwest of the Biga Peninsula, which has a high CPD, high heat flow value, and shallow Conrad discontinuity.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2025Shear-wave velocity model of the Sivas City (inner eastern, Türkiye) using Rayleigh wave ellipticity inversion controlled by 2D microgravity modeling
Bektaş, Özcan; Büyüksaraç, Aydın; Sarıtepe, Halil Erdim; Önal, Kemal Mert; Canbaz, Oktay; Eyisüren, Onur; Pamuk, Eren; Akın, Özgenç; Akar, Fahriye; Koşaroğlu, Sinan
The change in duration, amplitude, and frequency content of the earthquake ground motion as it passes through the rock and ground environment is referred to as the local ground effect. Impedance differences between bedrock and soil, as well as the dynamic behavior of soils, can amplify this effect. The geometry of both dense and loose soil layers must be known to accurately define soil–structure interaction and properly assess how soil behavior affects a structure during an earthquake. Local ground effects are known to play a significant role in structural damage during earthquakes. In basin-like environments, however, studies based on foundation and sub-base depth often lack sufficient information, making it difficult to identify problems associated with basin effects. It is not appropriate to provide construction-related information, especially in environments with a basin structure like Sivas, without determining the bedrock or solid ground conditions. This study aimed at determining the bedrock/seismic foundation depth for the central settlement of Sivas and defining the basin structure, involved large-scale microgravity measurements. The study area was modeled in three dimensions using the gravity data obtained. Long-term microtremor measurements were also conducted, and one-dimensional depth–shear-wave (Vs) velocity models were generated using the Rayleigh ellipticity method. The bedrock/seismic foundation structure of the study area was defined using two different methods, and these definitions were combined into two-dimensional sections. A depth map of the study area was created, revealing that the thickness of the loose basin unit is approximately 90 m. Ambient noise was recorded at 35 points with a velocity seismometer, and S velocity (Vs) profiles were obtained from joint inversion of Rayleigh ellipticity data and dispersion curves from MASW and ReMi data. Furthermore, the Vs-depth structure of the basin was defined along the profiles cutting the basin in NW–SE and S–N directions, based on the Vs velocities in the 2D gravity model. The frequency range along these profiles was found to be 0.6 Hz in the deep parts of the basin and 2.5 Hz in the shallow parts.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2024Geotechnical and Structural Damages Caused by the 2023 Kahramanmaraş Earthquakes in Gölbaşı (Adıyaman)
Akar, Fahriye; Işık, Ercan; Avcil, Fatih; Büyüksaraç, Aydın; Arkan, Enes; İzol, Rabia
On 6 February 2023, two independent earthquake pairs on the East Anatolian Fault Zone, with epicenters in Pazarcık (Mw = 7.7) and Elbistan (Mw = 7.6) districts of Kahramanmaraş province, caused great destruction. Adıyaman and Gölbaşı districts of this city are among the settlements most affected by the earthquake. Especially in the district where geotechnical damages are most observed, the destructive effects of earthquakes have been clearly observed in buildings with different structural systems. In this study, information is given about the earthquakes that hit the region and the fault zone where the earthquakes occur. Geotechnical and structural damages occurring in the villages and center of the district were evaluated within the scope of earthquakes and structural engineering. It can be stated that damages observed in the district center are generally caused by soil–structure interaction problems. The fact that masonry structures, which are widely used in rural areas, do not benefit from any engineering services has an impact on the level of damage. The main reason for the damages occurring in the reinforced concrete structures in the district is the reinforced concrete system that is not designed properly or not built in accordance with the design. This case study demonstrated the importance of earthquake–soil–structure interactions in line with earthquake-resistant building design principles.
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