Source Geometry Research Articles

Complex co- and postseismic faulting of the 2017–2018 seismic sequence in western Iran revealed by InSAR and seismic data

The largest earthquake in the Zagros Mountains struck the city of Azgeleh on the Iran–Iraq border on 12 November 2017. This Mw 7.3 earthquake was followed by an intense seismic sequence. Implementing the double-difference earthquake location technique, we relocate 1069 events recorded by our local seismic network, deployed after the mainshock. The spatial distribution of the epicenters indicates linear alignments of the events nucleated along at least four notable clusters. The clusters are characterized by at least one significant earthquake, such as the Tazehabad earthquake of 25 August 2018 (Mw 5.9) along a dense, east–west trending cluster and the Sarpol-e Zahab earthquake of 25 November 2018 (Mw 6.3) along the cluster with a northeast–southwest trend. We use two-pass differential SAR interferometry (DInSAR) and Small BAseline Subset (SBAS) methods to study the coseismic permanent displacements of the Azgeleh, Tazehabad and Sarpol-e Zahab events as well as the one-year postseismic deformation field of the 2017–2018 seismic sequence, respectively. We use non-linear and linear optimization algorithms to derive the source geometry and the slip distribution along the fault planes. The inversion is conducted by introducing also seismological constraints, leading to the definition of a listric geometry for the Azgeleh mainshock rupture that accommodates the slip area at depth of 10–16 km along a sub-horizontal plane (dipping ~3°) and a low-angle (~16°) ramp. The thrust and dextral movements along this NNW-striking (~345°) fault have triggered a tear fault responsible for the Tazehabad event ruptured an east–west trending (~267°), north-dipping (~78°) sinistral shear fault. We present the dextral slip distribution of the Sarpol-e Zahab event along a NE-striking (~34°) fault, as a synthetic Riedel structure for the southern segment of the Khanaqin fault, dipping 63° to the southeast. We find the postseismic deformation field associated with the seismic sequence is not confined only to the mainshock source (the Azgeleh fault), but also develops along the Tazehabad and Sarpol-e Zahab faults. We additionally propose afterslip along a duplex, flat-ramp-flat structure down-dip and up-dip of the Azgeleh coseismic slip area. The up-dip afterslip develops onto the shallow detachment (~3°) at depth of ~8 km and the down-dip afterslip propagate onto the mid-crustal décollement level within the Pan-African basement. The Azgeleh, Tazehabad, Sarpol-e Zahab and Khanaqin faults mark the Lurestan Arc–Kirkuk Embayment sharp margin in the Northwest Zagros and play a key role in the lateral escape of the Lurestan Salient and vertical strain partitioning in the Zagros front.

An improved probabilistic seismic hazard mapping of peninsular shield region of India

This paper attempts to present improved probabilistic seismic hazard maps of the peninsular shield of India based on data driven seismicity and ground motion models. Combination of nine conventional area sources described by Gutenberg and Richter's (G-R) recurrence relationship and a vast tectonic province of southern peninsular shield described by a zone-free kernel smoothing approach has been used independently. Similar to that for the conventional area sources, the expected occurrence rates of earthquakes in different magnitude bins are estimated from the G-R relationships, but distributed non-uniformly among a grid of square cells in accordance with the smoothed epicentral density of the observed past seismicity. On the other hand, the occurrence rates for the tectonic province source are obtained directly by kernel smoothing of the gridded past seismicity. Other distinguishing features of the present study are (a) the use of a very comprehensive and thoroughly scrutinized earthquake catalogue, (b) data driven selection of ground motion prediction equations (GMPEs) using the limited accelerogram records available, (c) estimation of the source-to-site distances by accounting for the effects of the regional strike and dip angles of the fault rupture planes for a perfect compatibility with the distances involved in the selected GMPEs, and (d) permitting the rupture length to extend beyond the zone boundaries in the estimation of the source-to-site distances, which along with the non-uniform distribution of seismicity is able to normalize to some extent the effect of any uncertainty in deciding the zone boundaries. As the geometries of the area sources are decided mainly on the basis of the major tectonic features in the region, the hazard maps obtained are seen to depict the desired conformity with them fairly well. Also, due to the use of the data-driven selection of the highest ranking GMPEs, the hazard maps obtained are expected to be representative of the peninsular region. The rock site uniform hazard spectra for 14 important sites in different parts of the peninsular India as obtained from the presented hazard maps are compared with the corresponding design spectra based on the ASCE/SEI 7–10 and BIS codal provisions, and necessary modifications are proposed in the ASCE provisions in order to get the design spectra specific to the peninsular India. The paper also proposes empirical amplification factors to obtain uniform hazard spectra for a given VS30 value from the computed rock site uniform hazard spectra.

Unsteady Heat Conduction Study During Underground Coal Gasiflcation For Constructing an In-situ Pyrolysis Project.(Dept.M)

Underground coal gasification (UCG) Is a potential coal utilization technology, receiving renewed interest around the world. In the last .five years there has been Increasing Interest In tile world energy and mining Industry for tile development of a new operating underground coal gasification systems to generate synthetic gas from underground coal seams. In this paper, the problem of unsteady heat conduction In the underground coal and rock layers during underground gasification Is considered. The heating of coal results In releasing considerable amount of gases mainly hydrogen and methane which would be collected and pumped through pipelines for use in different Industrial applications. In the present analysis, a spherical type heat source having a surface temperature of (1000OC, 1500OC, 1750OC and 2000OC) is used for heating the coal layer for achieving tile pyrolysis process. The differential equations describing the unsteady heat conduction in both coal and rock layers are solved numerically using the discretization method (control volume formulation). A computer program Is constructed for calculating the temperature fields and the gasified volumes of mineral coal as well as the heating velocity in the coal seams. In the experimental part, a model of an underground coal layer Is constructed. To validate the numerical model, an electrical spherical heat source Is Inserted directly into the coal layer for heating. The temperature distribution In coal layer is measured In different locations using the Thermocouples. The results show that the temperature profiles and the maximum attainable temperature in the coal seams depend on the time and the surface temperature of the heating reactor. Furthermore, the gasified volume of coal increase with the increase of both the surface temperature of the heating source and the running time. It is found also that the heating velocity in the underground coal. Lies between the mean value (2 to 10-3 K/min.) and increase with the time to reach a maximum value, after this it decrease to approach zero at the steady-state conditions. This study indicates that geometry, position, surface temperature and distribution of heating sources are very important parameters which should be carefully chosen for realizing an efficient pyrolysis of underground coal and avoiding thereby the combustion of a part of the coal seams. The analysis indicated that the best temperature is between (700-800oC) at which the high efficiency of pyrolysis process, the analysis might be useful in constructing an in-situ pyrolysis project for utilizing the underground coal seams.

Geometrical quasi-ballistic effects on thermal transport in nanostructured devices

We employ thermoreflectance thermal imaging to directly measure the steady-state two-dimensional (2D) temperature field generated by nanostructured heat sources deposited on silicon substrate with different geometrical configurations and characteristic sizes down to 400nm. The analysis of the results using Fourier’s law not only breaks down as size scales down, but it also fails to capture the impact of the geometry of the heat source. The substrate effective Fourier thermal conductivities fitted to wire-shaped and circular-shaped structures with identical characteristic lengths are found to display up to 40% mismatch. Remarkably, a hydrodynamic heat transport model reproduces the observed temperature fields for all device sizes and shapes using just intrinsic Si parameters, i.e., a geometry and size-independent thermal conductivity and nonlocal length scale. The hydrodynamic model provides insight into the observed thermal response and of the contradictory Fourier predictions. We discuss the substantial Silicon hydrodynamic behavior at room temperature and contrast it to InGaAs, which shows less hydrodynamic effects due to dominant phonon-impurity scattering.

Canonical X-Ray Fluorescence Line Intensities as Column Density Indicators

Abstract X-ray line fluorescence is ubiquitous around powerful accretion sources, namely, active galactic nuclei and X-ray binaries. The brightest and best-studied line is the Fe Kα line at λ = 1.937 Å(6.4 keV). This paper presents a survey of all well-measured Chandra/HETG grating spectra featuring several Kα fluorescence lines from elements between Mg and Ni. Despite the variety of sources and physical conditions, we identify a common trend that dictates the Kα line intensity ratios between elements. For the most part, the line intensities are well described by a simple, plane-parallel approximation of a near-neutral, solar-abundance, high column density (N H > 1024 cm−2) medium. This approximation gives canonical photon-intensity line ratios for the Kα fluorescence of all elements, e.g., 0.104:0.069:1.0:0.043 for Si:S:Fe:Ni, respectively. Deviations from these ratios are shown to be primarily due to excess column density along the line of sight beyond the Galactic column. Therefore, measured fluorescence line ratios provide an independent estimate of N H and insight into the environment of accretion sources. Residual discrepancies with the canonical ratios could be due to a variety of effects such as a fluorescing medium with N H < 1024 cm−2, a non-neutral medium, variations in the illuminating spectrum, nonsolar abundances, or an irregular source geometry. However, evidently and perhaps surprisingly, these are uncommon, and their effect remains minor.

Empirical formula for the quality factors of crack resonances and its application to the estimation of source properties of long-period seismic events at active volcanoes

SUMMARYLong-period (LP) seismic events at active volcanoes are thought to be generated by oscillations of fluid-filled resonators. The resonator geometry and fluid properties of LP sources have been estimated by comparing observed frequencies and quality factors (Q) with those calculated by numerical simulations with a crack model. A method to estimate all the parameters of crack geometry and fluid properties using an analytical formula for crack resonance frequencies has recently been proposed, but this method requires long computational times to compare observed and simulated Q values, especially for LP events with large Q. To resolve this problem, we used numerical simulations to systematically investigate the empirical relation between Q and crack model parameters. We found that Q can be calculated with an empirical formula expressed by the crack width-to-length ratio and the ratio of P-wave velocity in the solid medium to sound speed in the fluid. We applied this formula to LP events at Kusatsu–Shirane volcano, Japan, between 1992 August and 1993 January and at Galeras volcano, Colombia, in 1993 January. Assuming misty gas as the fluid in the crack at Kusatsu–Shirane and dusty gas as the fluid at Galeras, the empirical formula provided more detailed estimates of the parameters than those obtained previously using the Q values estimated in numerical simulations. We then applied the empirical formula to LP events with large Q values observed at Galeras between 2006 December and 2007 January. When we assumed dusty gas as the fluid in the crack, we found decreasing trends in both crack volume and the gas-weight fraction of water vapour in the crack. We also found that the dust volume was proportionally related to the product of crack aperture and crack length or width. These trends and relations were similar to those in 1993 January, suggesting that the LP events at Galeras between 2006 and 2007 were triggered by the explosive fragmentation of intruded magma and the production of a dusty gas, as was previously inferred for the LP events in 1993 January. Welding of ash in the dusty gas and dense magma remaining in the conduit after fragmentation led to a decrease in the source crack size prior to the next LP event. These results demonstrate that our empirical formula for Q can be used to estimate the source properties of LP events with large Q values without requiring long computational times. Use of the formula may thus contribute to improved monitoring of fluid states and understanding of LP triggering processes beneath many volcanoes.

Earthquake source properties from analysis of dynamic ruptures and far-field seismic waves in a damage-breakage model

SUMMARYWe present results on earthquake source properties using simulations of dynamic rupture and radiated seismic waves in a continuum damage-breakage rheological model. The source properties are derived by (1) calculation of source parameters directly from the simulated ruptures and (2) observational processing of the far-field radiated waves. The seismic potency, moment, damage-related source term, rupture velocity and effective rigidity are estimated directly from the simulated sources, while the radiation pattern, dominant frequency, directivity, rupture velocity and seismic potency are calculated through analysis of the radiated waves. The potencies calculated directly from the sources are used to validate those estimated by wave analysis. The effective rigidity at the rupture zone during failure is about four times smaller than that of the intact surrounding rocks. Rupture velocity can be estimated by far-field measurements for sources with unidirectional ruptures with prominent rupture directivity. The dominant frequencies for P and S waves $f_d^S/f_d^P$ reflect clearly the rupture duration and have a ratio in the range 0.87–1.12. Seismic potencies obtained through processing the P or S waves have an overall ±15 per cent difference from the source reference values. The calculated values of the coefficient ${\rm{\kappa }}$, relating rupture length to corner or dominant frequency, have strong dependency on the source geometry. Using a strain-rate dependent ${\rm{\kappa }}$, we obtain much weaker dependencies of strain-drop on the dominant frequencies, $\Delta {\rm{\varepsilon }} \propto {( {{f_d}} )^{3/4}}$, than the classical cube-dependency between stress drop and corner frequency, and corresponding weak dependency of average slip on dominant frequency, ${\rm{\bar{D}}} \propto {( {{f_d}} )^{1/2}}$. The obtained analysis procedure and relations can be used to reduce the uncertainty of source properties derived from far-field seismic waves.

Deformation transfer survey

Deformation transfer is a type of retargeting method that operates directly on the mesh and, by doing so, enables reuse of animation without setting up character rigs and a mapping between the source and target geometries. Deformation transfer can potentially reduce the costs of animation and give studios a competitive edge when keeping up with the latest computer animation technology. Unfortunately, deformation transfer has limitations and is yet to become standard practice in the industry. This survey starts by introducing Sumner and Popović’s [18] seminal work and highlights key issues for industry settings. We then review related work in sections, organized by these key issues. After surveying related work, we discuss how their advances open the door to several practical applications of deformation transfer. To conclude, we highlight areas of future work.

Deuteron and antideuteron coalescence in heavy-ion collisions: energy dependence of the formation geometry

We investigate the collision energy dependence of deuteron and antideuteron emission in the RHIC-BES low- to mid-energy range $\sqrt{s_{NN}} = 4.6-200$ GeV where the formation rate of antinuclei compared to nuclei is strongly suppressed. In the coalescence picture, this can be understood as bulk emission for nuclei in contrast to surface emission for antinuclei. By comparison with experimental data on the coalescence parameter $B_2$, we are able to extract the respective source geometries. This interpretation is further supported by results from the UrQMD transport model, and establishes the following picture: At low energies, nucleons freeze out over the total fireball volume, while antinucleons are annihilated inside the nucleon-rich fireball and can only freeze out on its surface. Towards higher energies, this annihilation effect becomes irrelevant (due to the decreasing baryochemical potential) and the system's freeze-out is driven by the mesons. Thus, the nucleon and antinucleon freeze-out distributions become similar with increasing energy.

Recovering the total magnetization direction using a novel stable reduction to the pole filter (RTP)

Interpretation of magnetic data commonly assumes that the total magnetization direction is parallel to the local geomagnetic field direction, leading to incorrect results when remanent magnetization is significant. This is a particular problem when applying interpretive filters that require knowledge of the direction of total magnetization. Here I present a novel frequency-domain, reduction-to-pole filter that is numerically stable for low latitudes and incorporates the influence of remanent magnetization. The operator is implemented through a differential algorithm that iteratively estimates the total magnetization direction. At each iteration, the code compares the ability of thirty pairs of inclination and declination values to minimize an objective function. After each comparison, the two pairs yielding the worst result are replaced by new values until the objective function is minimized. To improve results, two different methods were implemented to obtain a first guess for the inclination and declination: Helbig's integrals and comparison method. This first guess is used as reference to compose the first set of thirty pairs considered to calculate the RTP. A third possibility was also implemented, which uses thirty random pairs for the first interaction. Fisher's statistics are applied to the final population of estimated directions in order to determine the best mean direction. The new RTP filter is numerically stable and independent of a priori information about the source susceptibility, top depth, and geometry. The algorithm was tested on magnetic anomalies from several synthetic models and on real magnetic data and showed remarkable stability even in challenging settings.

Fault interactions in a complex fault system: insight from the 1936–1997 NE Lut earthquake sequence

SUMMARYCalculations of Coulomb stress changes have shown that moderate to large earthquakes may increase stress at the location of future earthquakes. Coulomb stress transfers have thus been widely accepted to explain earthquake sequences, especially for sequences occurring within parallel or collinear fault systems. Relating, under this framework, successive earthquakes occurring within more complex fault systems (i.e. conjugate fault system) is more challenging. In this study, we assess which ingredients of the Coulomb stress change theory are decisive for explaining the succession of three large (Mw 7+) earthquakes that occurred on a conjugate fault system in the NE Lut, East Iran, during a 30-yr period. These earthquakes belong to a larger seismic sequence made up of 11 earthquakes (Mw 5.9+) from 1936 to 1997. To reach our goal, we calculate, at each earthquake date, the stress changes generated by the static deformation of the preceding earthquakes, the following post-seismic deformation due to the viscoelastic relaxation of the lithosphere, and the interseismic deformation since 1936. We first show that accurately modelling the source and receiver fault geometry is crucial to precisely estimating Coulomb stress changes. Then we show that 7 out of 10 earthquakes of the NE Lut sequence, considering the uncertainties, are favoured by the previous earthquakes. Furthermore, the last two M7+ earthquakes of the sequence (1979 and 1997) have mainly been favoured by the moderate Mw ∼ 6 earthquakes. Finally, we investigate the link between the Coulomb stress changes due to previous earthquakes and the rupture extension of the next earthquake and show that a correlation does exist for some earthquakes but is not systematic.

Accuracy Estimation of Earthquake Source Geometry Parameters by the Sterling Interpolation Method in Nonlinear Inversion

Estimating the accuracy of source geometry parameters is helpful for understanding error propagation in a nonlinear inversion. To date, no studies have estimated the nonlinear inversion accuracy of source geometry parameters. Multipeak particle swarm optimization (MPSO) is used to invert source geometry parameters, providing them good reliability as is shown by Monte Carlo analysis. Also, Sterling interpolation is introduced to estimate the accuracy of nonlinear inversion of parameters in earthquakes. The square roots of variance in the source geometry parameters are obtained by the displacements and the corresponding errors. A simulation experiment illustrates that changing the number of observation points does not affect the accuracy of the seven source geometry parameters. When the number of observation points is constant, the square roots of variance in the source geometry parameters increase with an increase in noise in the observations. Finally, Sterling interpolation accuracy estimation as proposed is applied to the Lushan and L’Aquila earthquakes. We find that the random noise in the observation data affects the inversion results. The applicability and feasibility of the proposed method are verified.

Learning adaptive geometry for unsupervised domain adaptation

Unsupervised domain adaptation is an effective approach to solve the problem of dataset bias. However, most existing unsupervised domain adaptation methods assume that the geometry structures of data distributions are similar in the source and target domains. This assumption is invalid in many practical applications, because the training and test datasets usually differ in the variability modes and/or variation degrees. This paper handles the problem of inconsistent geometries by aligning both data representations and geometries. To overcome the lack of target labels in aligning geometries, this paper proposes learning the adaptive geometry that is derived from the domain-shared label space. Source and target geometries are aligned by constraining them with the unified criteria of the adaptive geometry. Combining the adaptive geometry learning and adversarial learning techniques, we develop a geometry-aware dual-stream network to learn the geometry-aligned representations. Experimental results show that our method achieves good performance on cross-dataset recognition tasks.

Quantitative and three-dimensional assessment of holdup material

Nuclear material deposited in equipment, transfer lines, and ventilation systems of a processing facility is usually referred to as holdup. Operators need to know the location and amount of holdup in their facility for radiation safety and material accountability. In this work, we propose to use an array of detectors co-axial to the inspected pipe to measure the holdup material. This method is implementable into an automated system capable of crawling on surfaces and pipes of various curvatures, which would enable faster, easier, and more accurate holdup safeguards measurements. We first demonstrated that the current holdup assay procedure could lead to a non-negligible bias in the estimate of special nuclear material mass, due to the simplified assumption of deposited geometry introduced by the Generalized Geometry Holdup (GGH) model. The new approach consists of imaging the inner holdup material by characterizing the detector array’s response and unfolding it from the measured light output. Our experimental proof of principle consists of three NaI(Tl) detectors surrounding an aluminum pipe containing two cesium-137 (137Cs) sources. We derived the source distribution inside the pipe by first calculating the detector response matrix using a method adaptive to the surface geometry of the object containing the measured holdup material. Creating a matrix of the detector array’s measured counts, we then proceed to solve an inverse problem, resulting in an accurately located source position and activity distribution within the response matrix’s spatial resolution. We then developed a simulated model of the envisioned experimental setup, which accurately described both the activity and position of the source in 2D. Finally, we extended our model onto a discretized three-dimensional model of the system, encompassing 36 detectors. The model was simulated to measure the source distribution and activity of multiple sources in pipes of varied geometries, which could then be conveniently translated to a real-time holdup measurement protocol. For the 3D simulation of four different source geometries, the model accurately localized the source position in 3D, while the activity retained a maximum relative error of ±5.32%.

Graphite Ion Source Geometry and Ne-Gas Pressure Dependent Growth and Morphology of Carbon Nanoclusters: AFM Analysis

The understanding of the growth and morphological evolution of nanoclusters with process parameters such as ion source geometry, voltage, current, time, and gas pressure are highly important to achieve their desired sizes, morphology, and concentration. Carbon nanoclusters (0-dimensional) were synthesized using the DC glow discharge technique at different process parameters (such as Ne-gas pressures, current, voltage, etc.) using custom fabricated graphite ion sources of cylindrical and U-shaped geometries. The morphology and density of carbon nanoclusters were studied with an atomic force microscope (AFM) to understand their evolution at different process parameters. The study suggests that the U-shaped hollow cathode ion source produces tiny carbon nanoclusters at greater concentration as compared to the cylindrical cathode. Similarly, the density of tiny nanoclusters enhances greatly with the increasing pressures (e.g., 75 mbar). In addition, the AFM morphology of the nanoclusters shows that they are more agglomerated at relatively lower pressure (e.g., 25 mbar). This may be due to the higher fragmentation of carbon soot with the increasing pressure because of more collisions among gas molecules and carbonaceous species. At controlled and optimized Ne-gas pressures and source geometry, carbon nanoclusters of the desired sizes can be fabricated, which may become promising candidates for nanoscale electronics, optoelectronic, and spintronic devices.

Search Space Reduction for Determination of Earthquake Source Parameters Using PCA andk-Means Clustering

The characteristics of an earthquake can be derived by estimating the source geometries of the earthquake using parameter inversion that minimizes the L2 norm of residuals between the measured and the synthetic displacement calculated from a dislocation model. Estimating source geometries in a dislocation model has been regarded as solving a nonlinear inverse problem. To avoid local minima and describe uncertainties, the Monte-Carlo restarts are often used to solve the problem, assuming the initial parameter search space provided by seismological studies. Since search space size significantly affects the accuracy and execution time of this procedure, faulty initial search space from seismological studies may adversely affect the accuracy of the results and the computation time. Besides, many source parameters describing physical faults lead to bad data visualization. In this paper, we propose a new machine learning-based search space reduction algorithm to overcome these challenges. This paper assumes a rectangular dislocation model, i.e., the Okada model, to calculate the surface deformation mathematically. As for the geodetic measurement of three-dimensional (3D) surface deformation, we used the stacking interferometric synthetic aperture radar (InSAR) and the multiple-aperture SAR interferometry (MAI). We define a wide initial search space and perform the Monte-Carlo restarts to collect the data points with root-mean-square error (RMSE) between measured and modeled displacement. Then, the principal component analysis (PCA) and thek-means clustering are used to project data points with low RMSE in the 2D latent space preserving the variance of original data as much as possible and extractkclusters of data with similar locations and RMSE to each other. Finally, we reduce the parameter search space using the cluster with the lowest mean RMSE. The evaluation results illustrate that our approach achieves 55.1~98.1% reductions in search space size and 60~80.5% reductions in 95% confidence interval size for all source parameters compared with the conventional method. It was also observed that the reduced search space significantly saves the computational burden of solving the nonlinear least square problem.

Mechanical Imaging of a Volcano Plumbing System From GNSS Unsupervised Modeling

AbstractIdentification of internal structures in an active volcano is mandatory to quantify the physical processes preceding eruptions. We propose a fully unsupervised Bayesian inversion method that uses the point compound dislocation model as a complex source of deformation, to dynamically identify the substructures activated during magma migration. We applied this method at Piton de la Fournaise. Using 7‐day moving trends of Global Navigation Satellite System (GNSS) data preceding the June 2014 eruption, we compute a total of 15 inversion models of 2.5 million forward problems each, without a priori information. Obtained source shapes (dikes, prolate ellipsoids, or pipes) show magma migration from 7–8 km depth to the surface, drawing a mechanical “tomography” of the magma pathway. Our results also suggest source geometries compatible with observed eruptive fissures and seismicity distribution. In case of finite magma volume involved in final dike injection, source volume estimates from this method allow forecasting volumes of erupted lava.

Geometry of the X-ray source 1H 0707–495

Aims. We investigate the constraints on the size and location of the X-ray source in 1H 0707–495 determined from the shape of the relativistically smeared reflection from the accretion disc. Methods. We developed a new code to model an extended X-ray source and we applied this code to all archival XMM observations of 1H 0707–495. Results. In contrast to earlier works we find that the relativistic reflection in this source is not consistent with an extended uniform corona. Instead, we find that the X-ray source must be very compact, at most a gravitational radius in size, and located at most a few gravitational radii from the black-hole horizon. A uniform extended corona produces an emissivity that is similar to a twice-broken power-law, but the inner emissivity is fixed by the source geometry rather than being a free parameter. In 1H0707–495, the reflection from the inner disc is much stronger than expected for a uniformly extended source. Including the effect of ionised absorption from the wind does not change this conclusion, but including scattered emission (and more complex absorption) from the wind can dramatically change the reflection parameters.

Fault modelling, seismic sequence evolution and stress transfer scenarios for the July 20, 2017 (MW 6.6) Kos–Gökova Gulf earthquake, SE Aegean

The July 20, 2017, MW 6.6 Kos–Gokova Gulf earthquake occurred offshore, near Bodrum of Turkey and Kos of Greece. It was one of the strongest in the broader area during the last many decades causing two deaths, many injuries and extensive damages. We investigated the evolution of the seismic sequence using seismological and geological tools. The aftershock sequence was relocated mainly in order to define the geometry of the main seismic source, depicting a NNW-dipping fault plane. It also revealed significant clustering, associated with other nearby faults, and asymmetric spatio-temporal evolution. Along with morphotectonic analysis on Kos Island, and other published seismological information (e.g. focal mechanisms), we modelled the seismic source of the mainshock, as well as the one of the strongest aftershocks (August 8, MW 5.3). We applied the Coulomb failure criterion in order to investigate the effect of the mainshock on the strongest aftershock, and the rest of the sequence as well. Using the same method, we also investigated the stress changes of both strongest shocks for the prevailing E–W-trending normal faults in this area. Among other conclusions and implications, we deduce that the prevailing tectonic setting of the Gokova Gulf consists of roughly E–W-striking normal faults forming inner horsts and grabens.

The May 11 Paphos, Cyprus, earthquake: implications for stress regime and tsunami modelling for the Eastern Mediterranean shorelines

The paper deals with the analysis of the propagation, heights, and arrival times of a tsunami that may occur on the coastal areas of Cyprus and Eastern Mediterranean in the case of an earthquake in southern Cyprus. Following a review of the seismic risk and historical earthquakes which occurred in southern Cyprus, it was concluded that this region may be subject to high vulnerability if a tsunami occurs. A study was conducted on the numerical modelling of a possible tsunami generated by movement along the fault of the 1222 Paphos earthquake. The region where the earthquake occurred can be attributed to the Cyprian Arc in the southwest of Cyprus. This arc is one of the most active seismic zones in the Mediterranean, which has led to the occurrence of earthquakes from submerged seismogenic sources. A methodology is used to simulate tsunami wave propagation for the Eastern Mediterranean coastal areas which requires the initial wave due to fault parameters as well as the bathymetry data. The GEBCO30 bathymetry data are used which have a grid spacing of 0.30 arc min. The fault parameters are deduced from the maximum stress directions and source geometry of the region from the moment tensor solutions derived from analyzing of earthquake waveforms. The numerical tsunami propagation model was performed by using SWAN code. The simulated highest tsunami heights were 4.02 m in Kouklia (Cyprus); 2.85 m in Paphos Ktima (Cyprus); 2.58 in Episkopi (Cyprus); 2.06 in Peyia (Cyprus); 1.76 in Yennadhi, Rhodes (Greece); 1.53 in Burg Migheizil (Egypt); 1.46 m in Tarabulus (Lebanon); 1.39 m in Bur Said (Egypt); 1.28 in Al-Burj (Egypt); and 0.60 in Mugla-Aksaz (Turkey). The results of the model outline the extent of the tsunami waves of damaging size, but destructive event in the region.