Active surface deformations detected by precise levelling surveys in the Afyon-Akşehir Graben, Western Anatolia, Turkey

Abstract

In the actively deforming region of western Anatolia, crustal deformation is accommodated by destructive earthquakes and a variety of aseismic events. In this study, we investigated the 2016–2017 aseismic sequence located in the Bolvadin Fault, one of the segments of the Akşehir-Simav Fault System of western Anatolia by analysing surface deformation derived from detailed geological mapping. Our findings suggest that surface deformation in the Bolvadin Fault is accommodated by aseismic episodes. During the field studies in the Bolvadin area, progressive surface deformations, such as surface faults and earth fissures with a length of 800 meters to 3 kilometres and strike of N15°E to N70°E were mapped on a 1/5000 scale. Furthermore, a levelling network was established to calculate the vertical displacements and deformation rate along the surface deformations. Precision level measurements were undertaken in 2016 and 2017. On the routes to the NW of the Bolvadin settlement, a vertical deformation rate of 30 mm/yr was detected in the period of 2016–2017, and a large deformation rate of 40 mm/yr was detected in the same period.

Late Holocene coseismic rupture and aseismic creep on the Bolvadin Fault, Afyon Akşehir Graben, Western Anatolia

“…As we documented earlier, after the 2002 Çay earthquakes, some progressive aseismic surface deformations began to develop as three prominent splays in Bolvadin city center (southwestern part of the Bolvadin Fault) whose length is up to 4 km with vertical displacements up to 70 cm. According to the precision level measurements performed by Tiryakioğlu et al (2019), the average rate of vertical displacement along these three splays is 85 mm/year. The deformation rate is compatible with the general values (between 6 and 10 cm/year) obtained from similar deformation regions in western Anatolia and USA (Holzer, 1984;Koca et al, 2011;Poyraz et al 2015;Özkaymak et al, 2017).…”

“…The front primary splay (fs) is also 3 km long and roughly parallel to the ms but located in approximately 2 km southeast of it. Vertical displacements up to 70 cm based on precise levelling were also obtained by Tiryakioğlu et al (2019) along the progressive surface deformation. According to precise levelling surveys across the middle splay, a vertical surface displacement rate of 40 mm/year was detected in the years 2016-2018, while the average throw rate along these three splays is 85 mm/year (Tiryakioğlu et al, 2019).…”

“…In this study, we present new palaeoseismic evidence for late Holocene activity of aseismic creeping on the Bolvadin Fault. In addition, we also include geologic mapping and trench observations by correlating with the precision level measurements of aseismic surface deformations (Tiryakioğlu et al, 2019) which has been developing on the Bolvadin Fault since the 2002 Çay earthquakes. To do this, we firstly introduce the seismotectonic setting of the region, then our findings (kinematic analysis and palaeoseismology) and their results, and finally we compare our results with the previous works.…”

GPS derived finite source mechanism of the 30 October 2020 Samos earthquake, Mw = 6.9, in the Aegean extensional region

“…Moreover, the antenna phase center was derived according to the height-dependent model. During the analysis, LC (L3), which is the ionosphere-independent linear combination of the L1 and L2 carrier waves, and the FES2004 Ocean Tide Loading (OTL) grid was used (Gülal et al, 2013;Tiryakioğlu et al, 2013Tiryakioğlu et al, , 2015Tiryakioğlu et al, , 2017aTiryakioğlu et al, , 2017bTiryakioğlu et al, , 2018bTiryakioğlu et al, , 2019. As a result, daily adjusted coordinates in ITRF2014 frame of all sites were calculated with the accuracy of ~6 mm for the horizontal components.…”

Monitoring the deformation of a concrete dam: a case study on the Deriner Dam, Artvin, Turkey

“…Many researchers have attempted to determine any displacements utilizing h 2 -criteria method in many deformation-related applications such as bridge (Erol et al 2005), mining (Kayikci and Yalcinkaya 2015), earthquake (Ozener et al 2013;Sabuncu and Ozener 2014;Tiryakioglu et al 2019), landslide (Yalçinkaya and Bayrak 2005;Acar et al 2008;Hastao glu 2013;Zeybek et al 2015), dam (Bayrak 2007). In order to detect any displacements with h 2 -criteria method, the geodetic network is measured at least two different observation times with geodetic methods.…”