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Author: Kosaroglu, Sinan

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    Article
    Citation - WoS: 13
    Citation - Scopus: 13
    Crustal Thickness in the Black Sea and Surrounding Region, Estimated From the Gravity Data
    (Elsevier Sci Ltd, 2021) Bilim, Funda; Aydemir, Attila; Ates, Abdullah; Dolmaz, M. Nuri; Kosaroglu, Sinan; Erbek, Ezgi
    In this research, the crustal thickness (Moho depth) variations in the Black Sea and surrounding region were calculated from the regional gravity anomaly data using an empirical equation. The data were obtained from the open source of Bureau Gravimetrique International (BGI) in digitized form. The gravity anomaly values are changing from 80 mGal in the onshore Black Sea region in Turkey to 260 mGal in the deeper parts of the sea. Maximum gravity anomaly indicates a consistent pattern in the offshore Black Sea and anomaly pattern follows the shape of the shoreline. The pattern is consistent with the deeper parts in the marine area and the eastern anomaly extends into the Russian territory between NW of Georgia and SE of the Crimean Peninsula. The crustal thickness map indicates almost the same trends. In this map, the minimum crustal thickness is about 10 km around the mid of the Shatsky Ridge, close to the coastal regions of SE Russia and the second thinnest (12 km) place is located around the Western Black Sea Basin. The maximum thicknesses are represented with the 34-36 km contours in the onshore Eastern Black Sea region and east of Anatolia. On the other hand, the maximum crustal thickness to the north can reach up to 28 km around the Sea of Azov and to the east. The thickness variations are generally related with the main tectonic trends in this region. The Analytic Signal (AS) and maxima points of the horizontal gradients (maxspots) maps constructed from the gravity anomalies are also prepared in this research to see if these anomaly trends follow the tectonic lines. The regions of maximum and minimum crustal thicknesses are well-consistent with the AS anomalies and boundaries of the bifocal thin crustal sections coinciding with the Eastern and Western Black Sea basinal parts are surrounded with the maxspots. The northern thick crustal region around the southern margin of the Indolo-Kuban Basin is also surrounded by the maxspots. It is possible to claim that the maxspots map from the horizontal gradient of Bouguer anomalies reflects the boundaries of the main tectonic units in the Black Sea Region. Particularly, southern boundary of the Scythian Platform, southern boundary of the Shatsky Ridge and Great Caucasus thrust are distinctive and easy to follow in the maxspots map.
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    Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Geophysical Investigation of the Geothermal Potential Under the Largest Volcanic Cover in Anatolia: Kars Plateau, Ne Turkey
    (Springer Basel Ag, 2020) Aydemir, Attila; Bilim, Funda; Avci, Birgul; Kosaroglu, Sinan
    In this study, Curie-point depth (CPD), geothermal gradient, radiogenic heat production, and heat flow maps were constructed based on different thermal conductivity coefficients using magnetic anomaly data for the Kars Plateau, which has the largest volcanic cover in Turkey. The bottom depths of the magnetic crust in the research area were revealed by the CPD map for the first time in this investigation. There are two apparent magnetic anomaly trends in the study area: the first is the Horasan-Senkaya-Sarikamis-Selim-Arpacay trend in the NE-SW direction, and the other is the Hanak-Ardahan-Arpacay trend in the NW-SE direction. Two other prominent elongations extend into the Ardahan-Gole-Senkaya and Kars-Digor axes. All these trends represent mountain chains and/or stratovolcanoes in the region, and no anomalies are observed around the non-volcanic outcrops. Curie depths are shallow, up to 14 km between Horasan and Kagizman towns, and 12 km in the northwestern part of the study area. Gradient values can reach 50 degrees C km(-1) in the northwestern sector, together with the high heat flows represented by the 150 Wm(-1) K-1 contours. The deepest CPD region lies between Gole and Susuz towns, where the geothermal gradient decreases to 27 degrees C km(-1). Heat flows decrease 60 Wm(-1) K-1 in the same area. An apparent gap around the Kars Plateau was observed in previous regional heat flow maps of Turkey by other authors (who used the bottom hole temperatures of boreholes and hot springs temperatures). This gap has been accurately filled from the results of this study, and geothermal exploration areas and the geothermal potential of the Kars Plateau have thus been determined for future exploration activity on the basis of the tectonic elements and earthquake data.
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    Article
    Relationship Between Crustal Magnetic Anomalies and Earthquake Activity in Malatya and Surrounding Region After the 2023 Kahramanmaraş Earthquakes, Southeastern Türkiye
    (Springer Int Publ Ag, 2026) Bilim, Funda; Kosaroglu, Sinan; Aydemir, Attila
    The East Anatolian Fault Zone (EAFZ) is one of the most critical and active tectonic elements in T & uuml;rkiye, and there are a significant number of high-magnitude earthquakes along with the EAFZ, mentioned in the historical documents and recorded in the instrumental periods in southeastern Anatolia. The latest devastating tectonic activity occurred on February 6, 2023 (Mw = 7.7), followed by another high-magnitude earthquake in the same day (Mw = 7.6) on this fault zone. More than 15,000 aftershocks (some of them are Mw >= 4.0) have been recorded since then. The EAFZ is composed of several sub-fault zones and their segments with different elongations. Although the majority of these segments indicate ruptures during the main shock and aftershocks, some of them (including the Malatya Fault) are still aseismic, including great potential to trigger high-magnitude earthquakes. In this study, we interpreted the magnetic data and the epicenter distributions of earthquakes to correlate the tectonic structures and active fault zones. The fault indicators (with maxspots) based on the different types of derivative transformations provided good correlations between the faults and magnetic discontinuities because almost all fault zones in the study area have been filled by the magmatic intrusions to create magnetic anomalies. The maxspots are also another practical tool to determine the possible segments of faults and/or exact locations of undefined magmatic intrusions. It is possible to claim that the faults have provided conduits for the intrusion of the causative bodies while triggering the earthquakes in this critical area. The earthquakes are generally recorded along the southern fault segments. As a result of these methods and correlations, we determined the exact location and the length of the Malatya Fault (approximately 220 km), which is represented with the low-magnitude earthquakes.