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The Periadriatic Fault System (PAF) is among the largest and most important post-collisional structures of the Alps; it accommodated between 150-300 km of right-lateral strike-slip motion between the European and Adriatic plates from about 35 until 15 Ma. Recent GPS data suggest that Adria-Europe convergence is still being accommodated in the Eastern Alps. However, according to instrumental and historical seismicity records, seismotectonic deformation is mostly concentrated in the adjacent Southern Alps. In this contribution, we present our first results for dating earthquakes along the PAF during the Quaternary by applying two trapped charge dating methods. Both Electron Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL) are especially useful as ultra-low temperature thermochronometers due to their dating range (a few decades to ~1 Ma) and low closing temperature (below 100°C). We aim to show which segments of the PAF system accommodated seismotectonic deformation by directly dating quartz and feldspar from fault gouges. For ESR, we measure the signals from the Al center in quartz following the single aliquot additive (SAAD) and single aliquot regenerative (SAR) protocols, focusing on the 100-150 µm grain size fraction. For OSL, we measure the IRSL signal at 50°C (IR50) and the post-IR IRSL signal at 225°C (pIRIR225) on potassium feldspar aliquots of the 100-150 µm grain size fraction. Our ESR results indicate the PAF system accommodated seismotectonic deformation during the last 1 Ma, while the OSL signals for all samples were in saturation. The minimum ages obtained from OSL suggest that the events are likely not younger than 0.4 Ma. We also studied a segment of the nearby Lavanttal Fault, for which our ESR results suggest that the last earthquakes strong enough to produce sufficient shear heating to produce a partial reset on the geochronometer probably happened before 4 Ma.

The Zagros Mountain Front Flexure (MFF) makes a prominent topographic and structural step along the Zagros Fold-Thrust Belt that accommodates a significant amount of shortening between the Eurasian and Arabian plates. Here, the structural style below the MFF in the Kurdistan Region of Iraq was reconstructed using balanced cross-sections and forward modeling, and Late Pleistocene-Holocene fault-slip rates were calculated across several structures using luminescence dating of river terraces along the Greater Zab River. A balanced and retro-deformable cross-section for the NW Zagros reveals that reverse displacement on a basement fault underlying the MFF, along with fault-related folding above the Triassic detachment, is indispensable to explain the observed structural relief. The uplift rates of river terraces, obtained from their elevation and ages, indicate ongoing slip on faults when integrated with the kinematics of fault-related folds for the structures. The basement fault underlying the MFF accommodates 1.46±0.60 mm a-1 of slip, while a more external basement fault further to the SW is accommodating less than 0.41±0.16 mm a-1. Horizontal slip rates from detachment folding above the Triassic detachment in two anticlines (Sarta and Safin) within the Zagros Foothills are 0.40±0.10 and 1.24±0.36 mm a-1, respectively. Balanced cross-section, distribution of river terraces, and regional topography indicate that basement thrusting, and ductile thickening of the crust are restricted to the NE parts of the belt, and the deformation is limited mainly to folding and thrusting of the sedimentary cover above a Triassic basal detachment there in the SW parts.

Large pre-historical earthquakes leave traces in the geological and geomorphological record, such as primary and secondary surface ruptures and mass movements, which are the only means to estimate their magnitudes. These environmental earthquake effects (EEEs) can be calibrated using recent seismic events and the Environmental Seismic Intensity Scale (ESI2007). We apply the ESI2007 scale to the 1992 MS7.3 Suusamyr Earthquake in the Kyrgyz Tien Shan, because similar studies are sparse in that area and geological setting, and because this earthquake was very peculiar in its primary surface rupture pattern. We analyze literature data on primary and secondary earthquake effects and add our own observations from fieldwork. We show that the ESI2007 distribution differs somewhat from traditional intensity assessments (MSK (Medvedev-Sponheuer-Karnik) and MM (Modified Mercalli)), because of the sparse population in the epicentral area and the spatial distribution of primary and secondary EEEs. However, the ESI2007 scale captures a similar overall pattern of the intensity distribution. We then explore how uncertainties in the identification of primary surface ruptures influence the results of the ESI2007 assignment. Our results highlight the applicability of the ESI2007 scale, even in earthquakes with complex and unusual primary surface rupture patterns.

The Mountain Front Flexure marks a dominant topographic step in the frontal part of the Zagros Fold–Thrust Belt. It is characterized by numerous active anticlines atop of a basement fault. So far, little is known about the relative activity of the anticlines, about their evolution, or about how crustal deformation migrates over time. We assessed the relative landscape maturity of three along-strike anticlines (from SE to NW: Harir, Perat, and Akre) located on the hanging wall of the Mountain Front Flexure in the Kurdistan Region of Iraq to identify the most active structures and to gain insights into the evolution of the fold–thrust belt. Landscape maturity was evaluated using geomorphic indices such as hypsometric curves, hypsometric integral, surface roughness, and surface index. Subsequently, numerical landscape evolution models were run to estimate the relative time difference between the onset of growth of the anticlines, using the present-day topography of the Harir Anticline as a base model. A stream power equation was used to introduce fluvial erosion, and a hillslope diffusion equation was applied to account for colluvial sediment transport. For different time steps of model evolution, we calculated the geomorphic indices generated from the base model. While Akre Anticline shows deeply incised valleys and advanced erosion, Harir and Perat anticlines have relatively smoother surfaces and are supposedly younger than the Akre Anticline. The landscape maturity level decreases from NW to SE. A comparison of the geomorphic indices of the model output to those of the present-day topography of Perat and Akre anticlines revealed that it would take the Harir Anticline about 80–100 and 160–200 kyr to reach the maturity level of the Perat and Akre anticlines, respectively, assuming erosion under constant conditions and constant rock uplift rates along the three anticlines. Since the factors controlling geomorphology (lithology, structural setting, and climate) are similar for all three anticlines, and under the assumption of constant growth and erosion conditions, we infer that uplift of the Akre Anticline started 160–200 kyr before that of the Harir Anticline, with the Perat Anticline showing an intermediate age. A NW-ward propagation of the Harir Anticline itself implies that the uplift has been independent within different segments. Our method of estimating the relative age difference can be applied to many other anticlines in the Mountain Front Flexure region to construct a model of temporal evolution of this belt.