Active Tectonics of the Alps-Dinarides junction – what have we learned?

The collision of the Adriatic Plate with Europe leads to crustal deformation in the Southern Alps-Dinarides transition. Many aspects of this deformation are still unknown. This concerns for example sources of historical earthquakes in the hinterland of the Southern Alpine orogenic front and the overall distribution and the partitioning of strain. Also, the response of the upper crust to deep-seated processes and the influence of the lithospheric architecture on active tectonics has not been fully understood. In many cases, the reason is the very low overall deformation rate in this region. Several projects in the framework of SPP2017 have shed light on these problems, and many new studies unrelated to the SPP have recently published exciting new results. In this presentation I summarize new findings from the fields of geodesy, seismology, structural geology, geomorphology, and earthquake geology. These studies have used GNSS and InSAR data, seismological data from the AlpArray and SWATH-D experiments, new high-resolution digital elevation models, satellite imagery, field mapping, near-surface geophysics, paleoseismology, and Quaternary dating techniques to understand the pattern of Late Quaternary tectonics. In Italy, most of the deformation is accommodated by thrusting on the Southern Alps mountain front, or thrusting has already stepped southward into the Friulian plain, partly on blind faults. This behavior is known from several contractional regimes around the world. Although strong historical earthquakes (M>6) occurred in the interior of the mountain chain, present-day seismicity is rather low. In this region, geological evidence of fault activity is poor because sedimentation/erosion and anthropogenic overprint outpace most tectonic signals on a Quaternary time scale. This is similar to southern Austria, where there is very poor geological evidence of active faulting, despite a record of strong historical earthquakes. New dating results from both deformed and undisturbed geomorphic markers allow us to place constraints on the maximum amount of deformation that is accommodated here. In Slovenia, a system of NW-SE striking right-lateral strike slip faults in a more than 60 km-wide zone takes up most of the deformation. Additionally, many smaller, <15 km long faults show postglacial activity. In general, the deformation is widely distributed. A similar behavior can be observed in may strike-slip fault systems worldwide. In the study area there is a first order correlation between the distribution of seismicity during the Quaternary and gradients of crustal thickness and crustal density. However, other processes like a still ongoing, though very slow eastward extrusion of Eastern Alps crustal material or vertical motions due to glacial isostatic rebound or erosion are likely to contribute to the overall pattern of active tectonics

Holocene surface ruptures of the Rurrand Fault, Germany—insights from palaeoseismology, remote sensing and shallow geophysics

The Lower Rhine Embayment in Central Europe hosts a rift system that has very low deformation rates. The faults in this area have slip rates of less than 0.1 mm/yr, which does not allow to investigate ongoing tectonic deformation with geodetic techniques, unless they cover very long time spans. Instrumental seismicity does only cover a small fraction of the very long earthquake recurrence intervals of several thousands of years. Paleoseismological studies are needed to constrain slip rates and the earthquake history of such faults. Destructive earthquakes are rare in the study area, but did occur in historic times. In 1755/56, a series of strong earthquakes caused significant destruction in the city of Düren (Germany) and the surrounding areas. In this study we document paleoseismological data from the nearby Rurrand Fault. In contrast to earlier studies on the same fault, we found evidence for a surface rupturing earthquake in the Holocene, and we identified at least one more surface rupturing event. Our study shows that the Rurrand Fault currently accommodates deformation in earthquakes rather than by creeping. The coseismic offsets were determined to be between less than 0.5 m per event. We assign maximum possible magnitudes of MW5.9-6.8 for the Rurrand Fault and a slip rate of at least 0.02-0.03 mm/yr for the last ~130-50 kyr. The surface ruptures did not occur at the main fault trace that has a clear morphological expression due to older tectonic motions, but on a younger fault strand in the hanging wall of the main fault. Terrain analyses based on 1 m resolution airborne LiDAR data have been used to image the subtle morphological expression of this young fault zone. Georadar and electric resistivity tomography were applied to image the fault zone at depth and to test if these shallow geophysical methods can be used to identify and trace the fault zone. Georadar failed to produce reliable results, but geoelectrics were successfully applied and allowed us to retrieve slip rate estimates. Our results indicate that the Düren 1755/56 earthquakes did not produce surface ruptures at the Rurrand Fault, either because they did not rupture the surface at all, or because they occurred at another, neighboring fault.This is the author accepted manuscript. The final version is available from Oxford University Press via http://dx.doi.org/10.1093/gji/ggv55

Pseudotachylites along the Pustertal-Gailtal-Line, eastern Periadriatic Fault system, Austria

The Pustertal-Gailtal Line (PGL) belongs to the dextrally transpressive Periadriatic Fault system and forms the border between Southern and Eastern Alps. Although part of the ongoing convergence between Adria and Europe appears to be accommodated by this fault system, it reveals little instrumental and historical seismicity. In our study, we attempted to find evidence for past seismic activity along the PGL by investigating pseudotachylite occurrences. We investigated an area of c. 19 km2 to either sides of the PGL around Maria Luggau (Austria). We identified cataclasites and fault gouges along the fault core zone, from which we investigated only the cohesive rocks. Cataclastic, foliated Oligocene granitoids as well as garnet-mica schists of the Austroalpine basement are crosscut by cm- to dm-scale veins containing black fault rocks, which were sampled for further analyses (Fig. 1). Polarisation microscopy reveals that the vein-forming black fault rocks are often optically isotropic, testifying to their origin as quenched melts. Sharp margins of mm- to cm-sized injection veins against the surrounding host rock, well-rounded quartz and feldspar clasts, the absence of hydrous minerals in the matrix, as well as spherulites are further hints at a seismogenic origin of the studied fabrics. Some of the optically isotropic veins are internally foliated; their in-situ µ-XRF analysis of major element concentrations revealed chemical composition variations in the foliation. Even if this foliation might suggest overprinting by aseismic creep, our observations indicate a seismogenic origin of the studied fabrics as pseudotachylites

Earthquake geology: science, society and critical facilities

Earthquake geology studies the effects, the mechanics and the impacts of earthquakes in the geological environment. Its role is also to decode the fault history, therefore its approach is fault specific and its outcomes are of decisive value for seismic hazard assessment and planning. The term Earthquake geology includes aspects of modern instrumental studies, tectonics and structural geology, historical surface deformation and tectonic geomorphology, whereas paleoseismology is considered part of earthquake geology [...]

Late Pleistocene‐Holocene Slip Rates in the Northwestern Zagros Mountains (Kurdistan Region of Iraq) Derived From Luminescence Dating of River Terraces and Structural Modeling

Abstract A significant amount of the ongoing shortening between the Eurasian and Arabian plates is accommodated within the Zagros Fold‐Thrust Belt. However, the spatial and temporal distribution of active shortening within the belt, especially in its NW part, is not yet well constrained. We determined depositional ages of uplifted river terraces crossing the belt along the Greater Zab River using luminescence dating. Kinematic modeling of the fault‐related fold belt was then used to calculate long‐term slip rates during the Late Pleistocene to Holocene. Our results provide new insight into the rates of active faulting and folding in the area. The Zagros Mountain Front Fault accommodates about 1.46 ± 0.60 mm a −1 of slip, while a more external basement fault further to the SW accommodates less than 0.41 ± 0.16 mm a −1 . Horizontal slip rates related to detachment folding of two anticlines within the Zagros Foothills are 0.40 ± 0.10 and 1.24 ± 0.36 mm a −1 . Basement thrusting and thickening of the crust are restricted to the NE part of the Zagros belt. This is also reflected in the regional topography and in the distribution of uplifted terraces. In the southwestern part, the deformation is limited mainly to folding and thrusting of the sedimentary cover above a Triassic basal detachment. In the NE, deformation is associated with slip on basement thrusts. Our study sheds light on the distribution of shortening in the Zagros Mountains and helps to understand the regional tectonic system. Our results may be the foundation for a better seismic hazard assessment of the entire area.Plain Language Summary In active mountain belts, river terraces found above the present‐day river level can be indicative of differences in uplift rates due to the thickening, faulting, and folding processes in the Earth&#39;s crust. These processes, driven by the motion of tectonic plates, are responsible for the formation of mountain belts. Here, we took sediment samples from uplifted river terraces along the Greater Zab River that crosses the Zagros Mountains in the Kurdistan Region of Iraq. We determined their deposition age using luminescence dating. From their age and elevation, we calculated uplift rates. We built a geometrical model of the fault zones in the area and determined how fast the slip occurs on these faults based on the uplift rates. Our results indicate that there were less than two millimeter per year of slip on these faults on average during the last 60 thousand years. This motion is a result of the convergence between the Arabian and Eurasian plates. With studies like this we can measure how fast fault blocks move, even if they were not associated with large earthquakes in the recent past. This approach helps to better assess the potential earthquake hazard in the area under investigation.Key Points We estimated fault slip rates in the NW Zagros Mountains by luminescence dating of river terraces and structural modeling There is c. 1.46 mm a −1 slip on the Mountain Front Fault and c. 1.64 mm a −1 slip from detachment folding in the NE part of the Foothill Zone Crustal thickening and basement thrusting occur in the NE parts of the Foothill Zone and only cover deformation occur in the SW part

МЕХАНІЗМ ІННОВАЦІЙНОГО РОЗВИТКУ РЕГІОНУ

Доценко О.Ю. Механізм інноваційного розвитку регіону / Економічний вісник НГУ № 3 Дніпропетровськ. 2012. – С.Розглянута структура механізму інноваційного розвитку регіону. Проаналізований сучасний стан фінансування інновацій в Україні та регіону. Уточнена класифікація джерел фінансування інноваційного розвитку регіон

Quaternary Seismic Slip in the Eastern Alps: Dating Fault Gouges from the Periadriatic Fault System Using Trapped Charge Dating Methods

The Periadriatic Fault System (PAF) is among the largest post-collisional structures of the Alps. Recent studies using GPS velocities suggest that Adria-Europe convergence is still being accommodated in the Eastern Alps. However, according to instrumental and historical seismicity records, earthquake activity is mostly concentrated along structures in the adjacent Southern Alps and adjacent Dinarides. Apart from ambiguous historical events, the PAF has little to no earthquake record. Electron spin resonance (ESR) and Optically Stimulated Luminescence (OSL) are dating methods that can be applied as ultra-low temperature thermochronometers (closing temperature below 100 °C), with a Quaternary dating range of a few decades up to ~2 Ma. Both are potentially applicable to date shear heating during earthquakes in slowly deforming fault zones. Since the saturation dose of the quartz ESR signals is larger than that of quartz and feldspar OSL, ESR enables establishing a maximum age of the events (assuming the resetting during seismic events was at least partial), while OSL allows finding their minimum age when the signal is in saturation. We analyzed fault gouge samples from 4 localities along the easternmost segment of the PAF (east of the Giudicarie Fault), and 5 localities along the southernmost segment of the Lavanttal Fault. For ESR, we measured the signals from the Al center in quartz, comparing the results from the single aliquot additive dose (SAAD) and single aliquot regenerative dose (SAR) protocols. Different grain size fractions were measured (SAR protocol) to establish a grain-size age plateau. For OSL, we measured the Infrared Stimulated Luminescence (IRSL) signal at 50 °C (IR50) and the post-IR IRSL signal at 225 °C (pIRIR225) on potassium feldspar. Additionally, experiments of thermal activation of the OSL signal in quartz were performed to observe the shear heating effect in different grain size fractions. For the PAF, the OSL shear heating sensitivity experiments show that quartz has been thermally activated to temperatures below 300 °C, corroborating that shear heating was sufficient for at least a partial system reset. The ESR grain size plateaus suggest that the most effectively reset fraction is 100-150 µm. In general, our dating results indicate that the studied segment of the PAF system accommodated seismotectonic deformation within a maximum age ranging from 1075 ± 48 to 349 ± 17 ka (ESR SAR) and a minimum age in the range of 196 ± 12 to 281 ± 16 ka (pIRIR225). The obtained ages and the current configuration of the structure suggest that the studied segment of the PAF could be considered a potentially active fault at least. In the case of the Lavanttal fault, the ESR dose-response curves were either close to or in saturation, allowing to obtain only minimum ages of ca. 4 Ma for the last total reset of the system. This could be the result of insufficient shear heating by low magnitude earthquakes, or the fault has not seen significant activity since then. Altogether, our results show that large structures in the Eastern Alps such as the PAF have accommodated part of the Adria-Europe convergence during the Quaternary and can potentially host earthquakes in the future

Late quaternary tectonic activity of the Udine-Buttrio Thrust, Friulian Plain, NE Italy

The NW-SE trending Udine-Buttrio Thrust is a partly blind fault that affects the Friulian plain southeast of Udine in NE Italy. It is part of a wider fault system that accommodates the northward motion of the Adriatic plate. Although seismic reflection data and morphological evidence show that the fault was active during the Quaternary, comparably little is known about its tectonic activity. We used high-resolution digital elevation models to investigate the surface expression of the fault. Measured vertical surface offsets show significant changes along strike with uplift rates varying between 0 and 0.5 mm/yr. We then analyze a topographic scarp near the village of Manzano in more detail. Field mapping and geophysical prospections (Georadar and Electrical Resistivity Tomography) were used to image the subsurface geometry of the fault. We found vertical offsets of 1–3 m in Natisone River terraces younger than 20 ka. The geophysical data allowed the identification of deformation of the fluvial sediments, supporting the idea that the topographic scarp is a tectonic feature and that the terraces have been uplifted systematically over time. Our findings fit the long-term behaviour of the Udine-Buttrio Thrust. We estimate a post-glacial vertical uplift rate of 0.08–0.17 mm/yr recorded by the offset terraces. Our results shed light on the Late Quaternary behaviour of this thrust fault in the complicated regional tectonic setting and inform about its hitherto overlooked possible seismic hazard

Формализованное описание цифрового устройства и его модель

Дано формализованное описание цифрового устройства в виде асинхронной модели, на основании которой разработан алгоритм моделирования произвольной логической сети. Алгоритм представлен на языке ЛЯПАС-71. Разработаны и отлажены на ЭВМ «М-220» соответствующие программы анализа цифровых устройств различной сложности

New constraints on extensional tectonics and seismic hazard in northern Attica, Greece: the case of the Milesi Fault

Northern Attica in Greece is characterized by a set of north dipping, subparallel normal faults. These faults were considered to have low tectonic activity, based on historical earthquake reports, instrumental seismicity, and slip rate estimates. This study presents new data for one of these faults, the Milesi Fault. We run GIS based geomorphological analyses on fault offset distribution, field mapping of post-glacial fault scarps, and ground penetrating radar profiling to image hanging-wall deformation. The first palaeoseismological trenching in this part of Greece allowed obtaining direct data on slip rates and palaeoearthquakes. The trenching revealed downthrown and buried palaeosols, which were dated by radiocarbon. The results of our investigations show that the slip rates are higher than previously thought and that at least four palaeoearthquakes with magnitudes of around M6.2 occurred during the last 4,000-6,000 years. We calculate an average recurrence interval of 1,000-1,500 years and a maximum throw rate of ~0.4-0.45 mm/a. Based on the new geological earthquake data we developed a seismic hazard scenario, which also incorporates geological site effects. Intensities up to IX must be expected for Northern Attica and the south- eastern part of Evia. Earthquake environmental effects like liquefaction and mass movements are also likely to occur. This scenario is in contrast to the official Greek seismic hazard zonation that is based on historical records and assigns different hazard zones for municipalities that will experience the same intensity by earthquakes on the Milesi Fault. We show that the seismic hazard is likely underestimated in our study area and emphasize the need to incorporate geological information in such assessments.This is the author accepted manuscript. The final version is available from Oxford University Press via http://dx.doi.org/10.1093/gji/ggv44