Cengiz Zabcı

Paleoseismological Evidence of Recent Earthquakes on the 1967 Mudurnu Valley Earthquake Segment of the North Anatolian Fault Zone

This study contributes paleoseismological data on the recent history of surface-rupturing earthquakes on the southern (main) branch of the North Anatolian fault zone (nafz, Turkey), west of the Bolu basin. We focused on the fault segment that ruptured during the 1967 Mudurnu Valley earthquake ( M s 7.1), which preceded the devastating earthquakes of 1999 in the sequence of westward-migrating nafz earthquakes since 1939. Geomorphological mapping was carried out in a search for trenching sites on the central part of the 22 July 1967 earthquake segment. In the absence of locations in sedimentary environments best suited for paleoseismological interpretation of faulted Holocene deposits, we trenched fluvial channel deposits at a terrace of the gravel- dominated Mudurnu River. The most conservative interpretation of the trench stratigraphy and faulting evidence suggests that at least one paleoearthquake (most probably two) occurred after a.d. 1693. The 1967 earthquake segment has ruptured at least once since the historical earthquake of a.d. 1668, which was previously considered to be a likely candidate for the penultimate event, and before 1967. It is not possible to confidently assign the penultimate event to one of the post a.d. 1693 historical earthquakes in the broader area around the Mudurnu Valley (e.g., the earthquake of a.d. 1719) because the historical data published so far do not provide conclusive information about when past ruptures of the Mudurnu Valley branch of the nafz (a secluded area) did or did not take place.

Spatial slip behavior of large strike‐slip fault belts: Implications for the Holocene slip rates of the eastern termination of the North Anatolian Fault, Turkey

We present new data on Holocene slip rates for the eastern end of the North Anatolian Fault (NAF) by using the optically stimulated luminescence ages of the offset terrace deposits at two sites, where a total of four displaced landforms was studied. Each offset feature was analyzed independently, and three different assumptions were made for all the offsets, depending on whether the age of the upper tread (upper tread reconstruction), the lower tread (lower tread reconstruction), or all bounding surfaces (intermediate solution) were used in dating of the terrace risers. The deflected geometry of the risers strongly suggests the use of either the intermediate solution or the upper tread reconstruction. The joint slip rate distributions for the upper tread reconstructions and the intermediate solutions were modeled as 13.0 + 1.8 / −1.4 and 14.3 + 5.8 / −2.4 mm/yr (2σ), respectively. Although the intermediate solution covers the full range of ages for the measured displacements, the curved geometry of the terrace risers suggests that the initiations of the riser offsets are most probably close to the abandonment ages of the upper terrace treads. Therefore, we accepted the joint slip rate of the intermediate solution but suggested that the average rate for the main displacement zone of the eastern NAF should be close to its lower limits. This slower rate with respect to previous estimates suggests that the total deformation is not only accommodated on the main displacement zone but is also distributed along the secondary faults to the south of the easternmost segments of the NAF.

Mechanics of plio-quaternary faulting around the Karliova triple junction: implications for the deformation of Eastern part of the Anatolian Scholle

ABSTRACT The intersection of the Eurasian and Arabian plates and the smaller Anatolian Scholle created the Karlıova Triple Junction (KTJ) in eastern Turkey. In this study, we present analogue model experiments for this region and compare the results with our field observations and data from remote sensing imagery. Our comparison suggests that the sense of slip along curvilinear faults at the west of the KTJ changes along strike moving away from the principal displacement zones, from strike-slip to oblique normal and then to pure normal slip. Although, the active Prandtl cell model has been proposed to explain the overall regional fault pattern at eastern part of the Anatolian Scholle, the map view orientation of the secondary faults within the Karlıova wedge and performed analogue modelling results suggest that the passive wedge-shaped Prandtl cell model with a normal dip-slip component along slip lines is more appropriate in order to explain not only deformation pattern around the KTJ but also internal deformation of eastern part of the Anatolia. Moreover, these faults accumulate the significant amount of deformation that causes to the irregular earthquake behavior and the relatively lower geologic slip-rates along the main fault branch of boundary faults around the KTJ. Abbreviations: Strike-slip; Karlıova Triple Junction (KTJ); continental deformation; North Anatolian Fault Zone (NAFZ); East Anatolian Fault Zone (EAFZ);Varto Fault Zone (VFZ)

Evidence for Tear Faulting from New Constraints of the 23 October 2011 Mw 7.1 Van, Turkey, Earthquake Based on InSAR, GPS, Coastal Uplift, and Field ObservationsEvidence for Tear Faulting from New Constraints of the 2011 Van, Turkey, Earthquake

The 23 October 2011 Mw 7.1 Van earthquake in eastern Turkey took place on a previously unknown thrust fault, causing over 600 fatalities and extensive damage mainly in Van city and the northern town of Erciş. Several coseismic models have already been published after the earthquake using the available seismological and geodetic data. These studies generally agree on a coseismic rupture on a north-dipping east–west-trending blind-thrust fault comprising one or two subparallel segments and the existence of a shallow slip deficit. Here, by introducing an additional coseismic pixel-offset dataset from the TerraSAR-X satellite, we conclude that a NNE–SSWtrending left-lateral tear fault that bounds the rupture to the east also slipped both during and after the mainshock, which is in agreement with both field observations and postseismic Global Positioning System (GPS) measurements. This has important implications for the seismic hazard analysis of the region as the extent and geometry of the rupture that we infer differ significantly from those previously proposed. Electronic Supplement: Figures showing comparison of the descending-mode Envisat Interferometric Synthetic Aperture Radar (InSAR) data and fault parameter trade-offs.