Seismotectonic study of the Fergana region (Southern Kyrgyzstan): distribution and kinematics of local seismicity

We present new seismicity and focal-mechanism data for the Fergana basin and surrounding mountain belts in western Kyrgyzstan from a temporary local seismic network. A total of 210 crustal earthquakes with hypocentral depths shallower than 25 km were observed during a 12-month period in 2009/2010. The hypocenter distribution indicates a complex net of seismically active structures. The seismicity derived in this study is mainly concentrated at the edges of the Fergana basin, whereas the observed rate of seismicity within the basin is low. The seismicity at the dominant tectonic feature of the region, the Talas-Fergana fault, is likewise low, so the fault seems to be inactive or locked. To estimate the uncertainties of earthquake locations derived in this study, a strong explosion with known origin time and location is used as a ground truth calibration event which suggests a horizontal and vertical accuracy of about 1 km for our relocations. We derived 35 focal mechanisms using first motion polarities and retrieved a set of nine moment tensor solutions for earthquakes with moment magnitude (Mw) ranging from 3.3 to 4.9 by waveform inversion. The solutions reveal both thrust and strike-slip mechanisms compatible with a NW-SE direction of compression for the Fergana region. Two previously unknown tectonic structures in the Fergana region could be identified, both featuring strike-slip kinematics. The combined analysis of the results derived in this study allowed a detailed insight into the currently active tectonic structures and their kinematics where little information had previously been available

Modelling Cross-Document Interdependencies in Medieval Charters of the St. Katharinenspital in Regensburg

To overcome the limitations of structural XML mark-up, graph-based data models and graph databases, as well as event-based ontologies like CIDOC-CRM (FORTH-ICS 2018) have been considered for the creation of digital editions. We apply the graph-based approach to model charter regests and extend it with the CIDOC-CRM ontology, as it allows us to integrate information from different sources into a flexible data model. By implementing the ontology within the Neo4j graph database (Neo4j 2018) we create a sustainable data source that allows explorative search queries and finally, the integration of the database in various technical systems. Our use case are the charters from the St. Katharinenspital, a former medieval hospital in Regensburg, Germany. By analysing charter abstracts with natural language processing (NLP) methods and using additional data sources related to the charters, we generate additional metadata. The extracted information allows the modelling of cross-document interdependencies of charter regests and their related entities. Building upon this, we develop an exploratory web application that allows to investigate a graph-based digital edition. Thereby, each entity is displayed in its unique context, i.e., it is shown together with its related entities (next neighbours) in the graph. We use this to enhance the result lists of a full-text search, and to generate entity-specific detail pages

Self-Consistent Assignment of Asparagine and Glutamine Amide Rotamers in Protein Crystal Structures

SummaryThe current protein structure database contains unfavorable Asn/Gln amide rotamers in the order of 20%. Here, we derive a set of self-consistent potential functions to identify and correct unfavorable rotamers. Potentials of mean force for all heavy atoms are compiled from a database of high-resolution protein crystal structures. Starting from erroneous data, a refinement-correction cycle quickly converges to a self-consistent set of potentials. The refinement is entirely driven by the deposited structure data and does not involve any assumptions on molecular interactions or any artificial constraints. The refined potentials obtained in this way identify unfavorable rotamers with high confidence. Since the state of Asn/Gln rotamers is largely determined by hydrogen bond interactions, the features of the respective potentials are of interest in terms of molecular interactions, protein structure refinement, and prediction. The Asn/Gln rotamer assignment is available as a public web service intended to support protein structure refinement and modeling

Detection of unrealistic molecular environments in protein structures based on expected electron densities

Understanding the relationship between protein structure and biological function is a central theme in structural biology. Advances are severely hampered by errors in experimentally determined protein structures. Detection and correction of such errors is therefore of utmost importance. Electron densities in molecular structures obey certain rules which depend on the molecular environment. Here we present and discuss a new approach that relates electron densities computed from a structural model to densities expected from prior observations on identical or closely related molecular environments. Strong deviations of computed from expected densities reveal unrealistic molecular structures. Most importantly, structure analysis and error detection are independent of experimental data and hence may be applied to any structural model. The comparison to state-of-the-art methods reveals that our approach is able to identify errors that formerly remained undetected. The new technique, called RefDens, is accessible as a public web service at http://refdens.services.came.sbg.ac.at

Seismotectonics of the Pamir

Based on a 2 year seismic record from a local network, we characterize the deformation of the seismogenic crust of the Pamir in the northwestern part of the India-Asia collision zone. We located more than 6000 upper crustal earthquakes in a regional 3-D velocity model. For 132 of these events, we determined source mechanisms, mostly through full waveform moment tensor inversion of locally and regionally recorded seismograms. We also produced a new and comprehensive neotectonic map of the Pamir, which we relate to the seismic deformation. Along Pamir's northern margin, where GPS measurements show significant shortening, we find thrust and dextral strike-slip faulting along west to northwest trending planes, indicating slip partitioning between northward thrusting and westward extrusion. An active, north-northeast trending, sinistral transtensional fault system dissects the Pamir's interior, connecting the lakes Karakul and Sarez, and extends by distributed faulting into the Hindu Kush of Afghanistan. East of this lineament, the Pamir moves northward en bloc, showing little seismicity and internal deformation. The western Pamir exhibits a higher amount of seismic deformation; sinistral strike-slip faulting on northeast trending or conjugate planes and normal faulting indicate east-west extension and north-south shortening. We explain this deformation pattern by the gravitational collapse of the western Pamir Plateau margin and the lateral extrusion of Pamir rocks into the Tajik-Afghan depression, where it causes thin-skinned shortening of basin sediments above an evaporitic décollement. Superposition of Pamir's bulk northward movement and collapse and westward extrusion of its western flank causes the gradual change of surface velocity orientations from north-northwest to due west observed by GPS geodesy. The distributed shear deformation of the western Pamir and the activation of the Sarez-Karakul fault system may ultimately be caused by the northeastward propagation of India's western transform margin into Asia, thereby linking deformation in the Pamir all the way to the Chaman fault in the south in Afghanistan

Impact of bending-related faulting and oceanic-plate topography on slab hydration and intermediate-depth seismicity

It is commonly assumed that intermediate-depth seismicity is in some way linked to dehydration reactions inside subducting oceanic plates. Although there is growing evidence that the hydration state of an oceanic plate is controlled by its structure and degree of faulting, we do not have a quantitative understanding of this relationship. Double seismic zones offer the possibility of investigating changes in oceanic-plate hydration not only along strike but also with depth beneath the slab surface. To quantify the impact of oceanic-plate structure and faulting on slab hydration and intermediate-depth seismicity, with a focus on the genesis of double seismic zones, we correlate high-resolution earthquake catalogs and seafloor maps of ship-based bathymetry for the northern Chilean and Japan Trench subduction zones. The correlations show only a weak influence of oceanic-plate structure and faulting on seismicity on the upper plane of the double seismic zone, which may imply that hydration is limited by slow reaction kinetics at low temperatures 5–7 km below the seafloor and by the finite amount of exposed wall rock in the outer-rise region. These factors seem to limit hydration even if abundant water is available. Seismicity in the lower plane is, in contrast, substantially enhanced where deformation of the oceanic plate is high and distributed across intersecting faults. This likely leads to an increase in the volume of damaged wall rock around the faults, thereby promoting the circulation of water to mantle depths where serpentinization is faster due to elevated temperatures. Increased lower-plane seismicity around subducting oceanic features such as seamounts or fracture zones may also be caused by enhanced faulting around these features. Our results provide a possible explanation for the globally observed presence of rather homogeneous upper-plane seismicity in double seismic zones as well as for the commonly patchy and inhomogeneous distribution of lower-plane seismicity

Korpusbasierte Analyse österreichischer Parlamentsreden

Dieser Beitrag beschreibt, wie aus Plenarprotokollen des Österreichischen Nationalrats generierte Korpora computerbasiert analysiert werden können. Konkret sollen dabei mit korpuslinguistischen Methoden diskursspezifische Schlagwörter und Wortgruppen (n-Gramme) aus den Nationalratsreden extrahiert werden. In einer Fallstudie wird auf die Beiträge der Abgeordneten zweier im politischen Spektrum weit voneinander entfernter Parteien fokussiert: GRÜNE und FPÖ. Mit Hilfe der so gewonnenen Daten soll die inhaltliche Analyse der stenografischen Protokolle erleichtert werden und die kontrastive Gegenüberstellung beispielsweise von Positionen, politischen Konzepten oder Wertvorstellungen in den Reden der Abgeordneten der unterschiedlichen Parteien ermöglicht werden

Elastin is heterogeneously cross-linked

Elastin is an essential vertebrate protein responsible for the elasticity of force-bearing tissues such as those of the lungs, blood vessels, and skin. One of the key features required for the exceptional properties of this durable biopolymer is the extensive covalent cross-linking between domains of its monomer molecule tropoelastin. To date, elastin's exact molecular assembly and mechanical properties are poorly understood. Here, using bovine elastin, we investigated the different types of cross-links in mature elastin to gain insight into its structure. We purified and proteolytically cleaved elastin from a single tissue sample into soluble cross-linked and noncross-linked peptides that we studied by high-resolution MS. This analysis enabled the elucidation of cross-links and other elastin modifications. We found that the lysine residues within the tropoelastin sequence were simultaneously unmodified and involved in various types of cross-links with different other domains. The Lys-Pro domains were almost exclusively linked via lysinonorleucine, whereas Lys-Ala domains were found to be cross-linked via lysinonorleucine, allysine aldol, and desmosine. Unexpectedly, we identified a high number of intramolecular cross-links between lysine residues in close proximity. In summary, we show on the molecular level that elastin formation involves random cross-linking of tropoelastin monomers resulting in an unordered network, an unexpected finding compared with previous assumptions of an overall beaded structure

Crustal surface-wave velocity structure of the east Albany-Fraser Orogen, Western Australia, from ambient noise recordings

Group and phase velocity maps in the period range 2-20 s for the Proterozoic east Albany-Fraser Orogen, Western Australia, are extracted from ambient seismic noise recorded with the 70-station ALFREX array. This two-year temporary installation provided detailed coverage across the orogen and the edge of the Neoarchean Yilgarn Craton, a region where no passive seismic studies of this scale have occurred to date. The surface wave velocities are rather fast overall (>3 km/s nearly everywhere), as expected for exposed Proterozoic basement rocks. No clear signature of the transition between Yilgarn Craton and Albany-Fraser Orogen is observed, but several strong anomalies corresponding to more local geological features were obtained. A prominent, NE-elongated high-velocity anomaly in the northern part of the array is coincident with a Bouguer gravity high caused by the upper crustal metamorphic rocks of the Fraser Zone. This feature disappears towards longer periods, which hints at an exclusively upper crustal origin for this anomaly. Further east, the limestones of the Cenozoic Eucla Basin are clearly imaged as a pronounced low-velocity zone at short periods, but the prevalence of low velocities to periods of ≥5 s implies that the uppermost basement in this area is likewise slow. At longer periods, slightly above-average surface wave velocities are imaged below the Eucla Basin.The Bouguer gravity anomaly map plotted in Fig. 2 is provided by Geoscience Australia (Bacchin et al. 2008; http://www.ga.gov.au/data-pubs/data -compilations/geophysics). We thank the various field crews who helped with data collection and the ANSIR instrument pool for the recorders and seismometers. C.V. Spaggiari and K. Gessner publish with the permission of the Director of the Geological Survey of Western Australia. Comments from two anonymous reviewers and the editor, Ana Ferreira, helped to considerably improve the manuscript

Relation Between Oceanic Plate Structure, Patterns of Interplate Locking and Microseismicity in the 1922 Atacama Seismic Gap

We deployed a dense geodetic and seismological network in the Atacama seismic gap in Chile. We derive a microseismicity catalog of >30,000 events, time series from 70 GNSS stations, and utilize a transdimensional Bayesian inversion to estimate interplate locking. We identify two highly locked regions of different sizes whose geometries appear to control seismicity patterns. Interface seismicity concentrates beneath the coastline, just downdip of the highest locking. A region with lower locking (27.5°S–27.7°S) coincides with higher seismicity levels, a high number of repeating earthquakes and events extending toward the trench. This area is situated where the Copiapó Ridge is subducted and has shown previous indications of both seismic and aseismic slip, including an earthquake sequence in 2020. While these findings suggest that the structure of the downgoing oceanic plate prescribes patterns of interplate locking and seismicity, we note that the Taltal Ridge further north lacks a similar signature