No abstract

Based on historical and instrumental data, societies in the Eastern Mediterranean and MiddleEast have survived at least 150 large earthquakes (generally M > 6) during the past 2500 yr. Beyond this time span, an earthquake chronology is mostly unknown, which hampers the production of reliable long-term earthquake models. Since the only remaining evidence of seismic activity is a bedrock scarp, cosmogenic 36 Cl is the only suitable nuclide to be applied in the determination of the seismic history and slip rate of an active limestone fault plane. In this study, we focus on the 4-m-high Mugırtepe fault scarp within the active Manisa fault zone in western Anatolia, one of the most seismically active and rapidly extending regions in the world. We analyzed 44 samples in two slightly overlapping strips, which in total covered 2.65 m of the fault scarp. In order to determine the timing and the amount of slip of the paleoseismic events, we analyzed the measured 36 Cl concentrations using the Schlagenhauf Matlab ® code. We used two different scenarios based on two different inherited 36 Cl concentrations as constrained by our data and modeling. The best fi t for the fi rst scenario yields two seismic events, one at 13.7 ± 0.8 ka with a displacement of 0.5 ± 0.2 m and one at 7.8 ± 0.5 ka with 2.15 ± 0.35 m offset. For the second scenario, we obtained a single seismic event at 8.6 ± 0.6 ka with 2.65 ± 0.35 m of slip. These results indicate that the visible part of the Mugırtepe exposed fault scarp had achieved most of its displacement already by 8 ka. Initial surface faulting at Mugırtepe occurred not later than around 14 ka, and marked seismic activity continued until around 8 ka. Our fi rst results from the western Anatolian Extensional Province show the ability to reveal periods of enhanced seismic activity beyond historical data using cosmogenic 36 Cl.

No abstract

No abstract

No abstract

Honaz Dağı (Honaz Mountain, Denizli) is the highest peak in western Anatolia (2517 m) and represents the southern margin of the Denizli Graben Horst System in the western Anatolia Extensional Province. Honaz Fault is a 2-km-wide, 15-km-long northward arc-shaped dip-slip listric normal fault that bounds the northern margin of Honaz Dağı, and has been formed under an N-S-trending extensional tectonic regime since the early Quaternary. This study uses fieldwork and digital elevation model-based geomorphic analysis to identify the kinematic behaviour of the Honaz Fault. Morphometric indices, such as axial river profiles, drainage basin geometries, triangular facets, mountain-front lineament patterns and sinuosities, document the impact of active tectonics on the evolution of the Honaz Fault and its surroundings, as do valley floor width-to-height ratios and mountain front facet characteristics. These neotectonic indices suggest a relatively high degree of tectonic activity along the Honaz Fault, and suggest that the Quaternary landscape evolution of Honaz Dağı was governed by structural and climate-related erosional processes. Combined geomorphic indices and field data suggest that the analysed dip-slip normal fault segments of the Honaz Fault are linear and highly active, and could generate earthquakes with magnitudes of 6.7. Morphometric analyses of the fault trace along the mountain front yield minimum slip rates of .15-.38 mm/y for the Honaz Fault, which are similar to slip rates calculated for active normal faults in the Aegean region.

No abstract

No abstract