Browsing by Author "Kahraman, Burcu"

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Late Quaternary Subsidence Records From the Datca Graben and Cnidus Ancient City (Sw Turkey): Sea-Level Changes Versus Tectonics
(Univ Barcelona, 2021) Ozsayin, Erman; Uner, Serkan; Kahraman, Burcu
The Datca Graben in southwestern Anatolia is a WNW-trending seismically active depression, with tectonic activity since Pliocene time. This tectonic activity is controlled by normal faults, which have effected ancient settlements. The Cnidus city (old and modern) -an ancient mercantile centre during the Hellenistic, Roman and Byzantine periods- is one of the places that has recorded this activity. The ancient harbour walls of Cnidus, lying 2.2-4.0m below sea level, contain important traces about sea-level changes and tectonics over the past 2.6kyr. Palaeostress analysis along boundary faults in the Datca graben yields an almost N-S oriented pure tensional regime, compatible with earthquake focal mechanism solutions located around the Datca peninsula. Additionally, an almost E-W trending surface rupture related to a historical earthquake in modern Cnidus, which shows normal fault characteristics, gives further support to the ongoing extension along the Kizlan, Karakoy and Cnidus fault zones. Previous studies on late Quaternary sea-level changes around the Datca peninsula suggest that 2.6kyr ago sea level was 1.0-1.25m lower than today. From the present-day depth of the old Cnidus harbour remains and regional sea-level records, it can be inferred that tectonics has played a significant role. Our calculations show that the Datca graben is subsiding at rates of 0.36-0.46mm/yr in the central part and 1.05-1.15mm/yr in the southern part. These values match those found in other areas around the Datca peninsula.
Tectonic Geomorphology of the Hoyran Graben (Western Anatolia, Türkiye): Insights From Geomorphic Indices
(Polish Geological inst, 2024) Cetin, Yaren Sena; Agar, Hasan Salih; Kahraman, Burcu; Bayram, Levent; Kul, Ahmet Ozkan; Ozsayin, Erman; Uner, Serkan
The area be tween West ern Anatolia and Isparta Bend com prises nu mer ous de pres sions and the ac tive faults that bound them. The Hoyran Graben is one of these de pres sions, lo cated at the north ern most part of the Isparta Bend. This NE-SW-ori ented graben is bounded by the Hoyran Fault in the north west and the Uluborlu, Senirkent and Kumdanli faults in the south-east, re spec tively. We eval u ate the seis mic ac tiv ity po ten tial among seg ments of the bound ary faults in the light of field work and morphometric in di ces. These bound ary faults of the Hoyran Graben are di vided into twelve seg ments for the analysis, with indices used including mountain-front sinuosity (Smf: 1.05-2.02), val ley floor width-to-val ley height ra tio (Vf: 0.11-1.34), hypsometric curve and in te gral (Hi: 0.4-0.73), asymmetry factor (Af: 13.76-87.03), stream length-gra di ent (SL: 1.48-9450) and nor mal ized chan nel steep ness (Ksn: 2.38-990.38). The re sults ob tained, to gether with field ob ser va tions, in di cate that the Uluborlu, Senirkent and Kumdanli faults, as well as the west ern seg ments of the Hoyran Fault, rep re sent higher po ten tial in terms of seis mic ac tiv ity with up lift rates >0.5 mm/y, while the cen tral and east ern seg ments show mod erate ac tiv ity with up lift rates be tween 0.05 and 0.5 mm/y. Thus, the bound ary faults of the Hoyran Graben need fur ther at ten tion in terms of re gional seis mic haz ard.