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Artificial corner reflectors (CRs), passive (which have no electronic parts), or active ones, so called electronic CR (ECR) or compact transponders (CAT), are devices which reflect the radar signal back to the SAR satellites and provide measurement points at desired locations. Using, such devices we can measure temporal Line of sight (LOS) changes of the CRs using the InSAR technique and for example monitor the ground movements precisely.Since January 2020, Lantmäteriet, the Swedish mapping, cadastral and land registration authority, has installed three ECRs and several types of passive reflectors (different shape and size, planned for C-band Sentinel-1 satellites) in different locations in Sweden. So far, ECRs are still functioning with no electronic failure. However, from the ESA Geodetic SAR project (https://eo4society.esa.int/projects/sar-hsu/) we experienced that the ECRs electronic characteristics are different, so individual calibrations maybe required by the manufacturer. In addition, thermal effects may also cause problems for measurements with ECRs. Therefore, instead of installing more ECRs, we switched to passive ones which have no electronics and have already shown their high-quality performance in different studies. So far, we have installed ten CRs in different locations and the goal is to continue and complement the national geodetic infrastructure of Sweden with at least twenty passive reflectors which are co-located with permanent GNSS stations. Among others, these co-located corner reflectors can potentially contribute to the development of the national and European ground motion services in future updates. Moreover, the co-location helps to map the relative ground motions estimated with InSAR to an absolute geodetic reference frameAmong different tests and performance analysis of such reflectors, we did multipath analysis to investigate if our corner reflectors cause any multipath error on nearby GNSS stations. We looked at the coordinate time series of the twin GNSS stations at two locations, Visby and Sveg. The installed corner reflector, double back-flipped squared, in Sveg is about 6 m away from the GNSS stations whereas, in Visby, the twin corner reflectors, ascending and descending, are about 20 meters away and have a trihedral squared trimmed shape. The daily GNSS coordinate time series for three components before and after installation of the corner reflectors didn’t show any significant jump in the time series and the coordinate variations are in the range of expected mm-level variations for all stations.

Environmental monitoring of mining regions using satellite imagery is crucial for sustainable exploitation and preventing geohazards. Movements due to the failure of the roof in underground coal mining, by migrating upwards and outwards from the seam being mined, could eventually appear as ground deformation. To investigate the matter further, the surface deformation that occurred over the Pabdana mining area was monitored in three time periods, between October 2, 2014, and July 27, 2019. Persistent scatterer interferometry (PSI) was used based on 150 ascending and descending Sentinel-1A images. The maximum mining subsidence rate during the studied periods was about 30 to 35 mm/yr. The PSI analysis shows that the subsidence rate varied both temporally and spatially during the three studied periods. The time series and the displacement rate for various cross-sections highlight a clear quantitative relationship between coal extraction progress and subsidence, which proceeded southward throughout the three study periods. So, considering coal mining subsidence as a geohazard, land developments and structures over the mining area may be safeguarded. The approach used in this investigation can be implemented in other similar coal mining zones.

In this study, three different procedures: checkpoint RMS of residuals, statistical evaluation of AT results using t-test, and comparison of a photogrammetric digital surface model (DSM) and LiDAR data are used to analyse the effect of IMU and GNSS uncertainties on the final adjusted results. The outcome suggests that the method of block-wise GNSS shift correction is the better method for aerial triangulation and one should use appropriate observable weights in AT. The comparison of checkpoint RMS residuals between the two methods shows that the block-wise solution is on average 6cm more accurate than the strip-wise solution.

The interest for using Interferometric Synthetic Aperture Radar (InSAR) for ground motion detection and monitoring is rapidly increasing, thanks to the Copernicus Senetinel-1 satellites which cover relatively large areas with a 6-days revisit time. Ground motion of many locations, especially urban areas around the world have been studied using Sentienl-1 data and the rate and distribution of the ground movements have been reported. For Sweden, for example, Fryksten and Nilfouroushan (2019) and Gido et al. (2020) studied the active ground subsidence in Uppsala and Gävle cities using the Senetinel-1 data collected between 2015-2020. The Persistent Scatterer Interferometry (PSI) technique was used to estimate the subsidence rate and the results were validated with the help of precise levelling data and correlated with the geological observations. Today, fortunately, we have the nationwide GMS of Sweden (https://insar.rymdstyrelsen.se) covering almost the entire country, which provides an opportunity to compare and cross-check the results of this new service with previous studies, for example the ones reported for Uppsala and Gävle cities. The temporal coverage of satellite data used for the GMS of Sweden has an overlap with the data used in previous studies for Uppsala and Gävle cities, and the same PSI technique has been used to generate the displacement map and time series.In this study, we used the previous PSI results of Uppsala and Gävle cities to validate the newly launched nationwide GMS of Sweden. The Line Of Sight (LOS) displacement time-series at some deforming locations were compared for both PSI-results. Although the number and imaging date of Senetinel-1 data, and the parameters used for PSI processing are not completely the same, the compared results show a good agreement between corresponding studies on the localization and rate of the subsidence in those two cities in last ~5 years. The validation phase of the new GMS of Sweden is in progress and our study shows the promising results, at least for urban areas in those two cities. ReferencesFryksten J., Nilfouroushan F., Analysis of Clay-Induced Land Subsidence in Uppsala City Using Sentinel-1 SAR Data and Precise Leveling. Remote Sens. 2019, 11, 2764. https://doi.org/10.3390/rs11232764Gido N.A.A., Bagherbandi M., Nilfouroushan F., Localized Subsidence Zones in Gävle City Detected by Sentinel-1 PSI and Leveling Data. Remote Sens. 2020, 12, 2629. https://doi.org/10.3390/rs12162629

Phase delay caused by atmospheric effects due to spatial and temporal variations of pressure, temperature, and water vapor content is one of the major error sources in estimation of ground deformation by interferometric synthetic aperture radar (InSAR>). Therefore, accuracy of ground deformation measurement is highly contingent on the robustness of the atmospheric correction techniques. These techniques rely either on auxiliary data such as numerical weather models (NWMs) or on the analysis of the interferometric phase itself. The accuracy in phase delays estimation of mixing effects of turbulent delay in atmosphere and stratified delay in lower troposphere is a key factor in determination of performance of each technique. Hence, the performance evaluation of the techniques is required in order to assess their potentials, robustness, and limitations. This article analyzes and evaluates the performance of four NWMs (i.e., ERA-Interim, ERA5, MERRA2, and WRF) and two phase-based techniques (i.e., linear and power law) to estimate phase delay using Sentinel-1A/B data over the Corvara landslide located in the Alps. The GPS data and GACOS product were used to validate the results. We generally found that ERA5 outperformed among other weather models with a phase standard deviation reduction of 77.7% (with respect to the InSAR phase), a correlation coefficient of 0.86 (between InSAR phase and estimated tropospheric delay) and a less significant error in the velocity estimation of the landslide.

The active tectonic deformation and hazardous earthquakes in the south and west of the Lut block have been investigated for a long time. In this study, we compute the geodetic and seismic strain rates using focal mechanism data from the Harvard CMT catalogue and various other sources including the published GPS velocities. Moreover, we also perform Focal Mechanism Stress Inversion (FMSI) to deduce a stress model for the region. Our study shows an expected correlation between the stress orientations, seismic and geodetic strain rates. Our results show that the south and west of the Lut block is generally exposed as a compressional strike-slip tectonic regime. The tectonic convergence in this area is taken up not only by motions along and across the faults but also by the rotation of those blocks which bounded by these faults. The maximum amount of rotation rate is observed where there are the main right lateral strike slip fault systems such as Sabzevaran, Gowk, Nayband, Bam, Kuhbanan, and Kahurak. The orientation of the mean stress direction, obtained from the FMSI results in the west and south of the Lut block, is approximated ~N19 E. In this area, faults are almost oblique relative to the tectonic motion direction. Moreover, there are right-lateral and left-lateral shears, in addition to the dip movements in different parts of the south and west of the Lut block. Our analyses show three main categories of the stress regimes including strike-slip faulting (43.2%), thrust faulting (38.6%), and unknown or oblique faulting (18.2%). We also calculated seismic and geodetic moment rates for this area, which indicate the seismic moment rate is relatively high between Bam and Shahdad where there are some segments of the Gowk fault.

There is over 15,600 km of track in the Swedish railroad network. This network is vital for the transportation of people and goods across the country. It is important that this network is monitored and maintained to ensure good function and safety. A tool for monitoring and measuring ground deformation over a large area remotely with high frequency and accuracy was developed in recent decades. This tool is known as Interferometric Synthetic Aperture Radar (InSAR), and is used by researchers, geo-technicians, and engineers.The purpose of this study has been to evaluate the use and feasibility of the InSAR technique for track condition monitoring and compare it to conventional track condition monitoring techniques. Malmbanan, which is primarily used to transport iron-ore from mines in Sweden to the ports of Luleå, Sweden and Narvik, Norway, is used as a case study for this project; specifically, the section between Kiruna and Riksgränsen. Coordinate matching of measurements from the provided Persistent Scatterer Interferometry (PSI) InSAR data and Optram data from survey trains were performed. Then measured changes over different time spans within the two systems were overlapped and classified with different thresholds to see if there is correlation between the two systems. An extensive literature review was also conducted in order to gain an understanding of InSAR technologies and uses.The literature review showed that there is a large potential and a quickly growing number of applications of InSAR to monitor railways and other types of infrastructure, and that the tools and algorithms for this are being improved. The case study, on the other hand, shows that it can be difficult to directly compare measurement series from different tools, each working on different resolutions in terms of both time and space. InSAR is thus not about to replace techniques such as those behind Optram (using measurement trains). Instead, the approaches offer complementary perspectives, each highlighting different types of issues.We find that InSAR offers a good way to identify locations with settlements or other types of ground motions. Especially transition zones between settlements and more stable ground can be challenging from a maintenance point of view and can clearly be identified and monitored using InSAR. With the rollout of national InSAR-data, and the large increase in data accessibility, we see a considerable potential for future studies that apply the technique to the railway area. Satellite monitoring of railways using InSAR

We used more than one decade of core-refracted teleseismic shear (SKS) waveforms recorded at more than 160 broadband seismic stations across the Iranian plateau and Zagros to investigate seismic anisotropy beneath the region. Splitting analysis of SKS waveforms provides two main parameters, i.e., fast polarization direction and split delay time, which serve as proxies for the trend and strength of seismic anisotropy beneath the stations. Our observation revealed a complex pattern of splitting parameters with variations in the trend and strength of anisotropy across the tectonic boundaries. We also verified the presence of multiple layers of anisotropy in conjunction with the lithosphere deformation and mantle flow field. Our observation and modeling imply that a combined system of lithosphere deformation and asthenospheric flow is likely responsible for the observed pattern of anisotropy across the Iranian Plateau and Zagros. The rotational pattern of the fast polarization directions observed locally in Central Zagros may indicate the diversion of mantle flow around a continental keel beneath the Zagros. The correlation between the variation in lithosphere thickness and the trend of anisotropy in the study area implies that the topography of the base of lithosphere is also a determining factor for the pattern of mantle flow inferred from the observations.

Monitoring environmental hazards, due to natural and anthropogenic causes, is one of the important issues, which requires proper data, models, and cross-validation of the results. The geodetic satellite missions, e.g. the Gravity Recovery and Climate Experiment (GRACE) and Sentinel-1, are very useful in this aspect. GRACE missions are dedicated to model the temporal variations of the Earth’s gravity field and mass transportation in the Earth’s surface, whereas Sentinel-1 collects Synthetic Aperture Radar (SAR) data which enables us to measure the ground movements accurately. Extraction of large volumes of water and oil decreases the reservoir pressure, form compaction and consequently land subsidence occurs which can be analyzed by both GRACE and Sentinel-1 data. In this paper, large-scale groundwater storage (GWS) changes are studied using the GRACE monthly gravity field models together with different hydrological models over the major oil reservoirs in Sudan, i.e. Heglig, Bamboo, Neem, Diffra and Unity-area oil fields. Then we correlate the results with the available oil wells production data for the period of 2003-2012. In addition, using the only freely available Sentinel-1 data, collected between November 2015 and April 2019, the ground surface deformation associated with this oil and water depletion is studied. Due to the lack of terrestrial geodetic monitoring data in Sudan, the use of GRACE and Sentinel-1 satellite data is very valuable to monitor water and oil storage changes and their associated land subsidence over our region of interest. Our results show that there is a significant correlation between the GRACE-based GWS change and extracted oil and water volumes. The trend of GWS changes due to water and oil depletion ranged from -18.5 to -6.2 mm/year using the CSR GRACE monthly solutions and the best tested hydrological model in this study. Moreover, our Sentinel-1 SAR data analysis using Persistent Scatterer Interferometry (PSI) method shows high rate of subsidence i.e. -24.5, -23.8, -14.2 and -6 mm/year over Heglig, Neem, Diffra and Unity-area oil fields respectively. The results of this study can help us to control the integrity and safety of operations and infrastructure in that region, as well as to study the groundwater/oil storage behavior.

Land subsidence and its subsequent hazardous effects on buildings and urban infrastructure are important issues in many cities around the world. The city of Uppsala in Sweden is undergoing significant subsidence in areas that are located on clay. Underlying clay units in parts of Uppsala act as mechanically weak layers, which for instance, cause sinking of the ground surface and tilting buildings. Interferometric Synthetic Aperture Radar (InSAR) has given rise to new methods of measuring movements on earth surface with a precision of a few mm. In this study, a Persistent Scatterer Interferometry (PSI) analysis was performed to map the ongoing ground deformation in Uppsala. The subsidence rate measured with PSI was validated with precise leveling data at different locations. Two ascending and descending data sets were analyzed using SARPROZ software, with Sentinel-1 data from the period March 2015 to April 2019. After the PSI analyses, comparative Permanent Scatterer (PS) points and metal pegs (measured with precise leveling) were identified creating validation pairs. According to the PSI analyses, Uppsala was undergoing significant subsidence in some areas, with an annual rate of about 6 mm/year in the line-of-sight direction. Interestingly, the areas of great deformation were exclusively found on postglacial clay.

In this paper, the authors studied the 2005 Dahuieh Zarand earthquake in SE Iran by combining Coulomb stress changes, InSAR study, locally recorded aftershocks and their spatial correlations, co-seismic slip distributions, Iso-seismal curves, and strong ground motion data. The event (M W 6.4) occurred in Kerman province, SE Iran, on February 22, 2005. The locally recorded aftershocks were used to calculate the Coulomb stress changes and the decay time based on Omori's law. The decay time of aftershocks calculated by Omori's law was about 500 days. A great correlation was particularly deduced from the spatial distribution of the aftershocks and areas of increased Coulomb stress for optimal strike slip faults . Moreover, using SAR Interferograms , we determined the postseismic surface deformations. Also, the majority of the coseismic slips occurred in the eastern part, where there was sparsely distributed aftershocks. The deformation maps showed active uplift for at least 300 days after the main shock. We reconciled time decays of the aftershocks with the postseismic uplifts, calculated from InSAR. In our model, which is based on after slip evolution, for one of the postseismic relaxation mechanisms, we found a proper correlation between the aftershock decay time and InSAR displacement maps to define postseismic motions. There is also a reasonable correspondence between the mainshock intensity, the acceleration map, and postseismic ground uplift, estimated by InSAR.

We run a series of analogue models to study the effect of stratigraphic heterogeneities of an evaporite formation on thin-skinned deformation of the Southeastern Pyrenean Basin (SPB; NE Spain). Thi ...

We analyze deformation of the Fars Arc in the eastern Zagros, Iran, including earthquake slip vectors, GPS velocities, paleomagnetism data, and fold orientations, to understand how this fold‐and‐thrust belt works, and so better understand the generic issue of fold‐and‐thrust belt curvature. The Fars Arc is curved, convex southwards. GPS‐derived rotation rates are ≤0.5° Myr‐1: rotation is clockwise west of 53° E, and counter‐clockwise to the east. These rotation senses are opposite to previous predictions of passive “bookshelf” models for strike‐slip faults during north‐south convergence. West of 53° E, average GPS vectors, thrust earthquake slip vectors, strain axes derived from GPS data and orthogonal directions to fold trends are all aligned, towards ~218°. East of this meridian, the average GPS vector is towards 208°, but the averages of the other datasets are distinctly different, all towards ~190°. We propose that fault blocks in eastern Fars, each ~20‐40 km long, rotate predominantly counter‐clockwise, whereas in western Fars the regional clockwise rotation takes place mainly on the array of active right‐lateral faults in this area. Thus localized block faulting and rotations accumulate to produce the overall strain and regional curvature. Active folds of different orientations in eastern Fars intersect to produce domal interference patterns, without involving separate deformation phases, indicating that fold interference patterns should not be interpreted in terms of changing stress orientations unless there is clear evidence. Fars Arc curvature is best explained by deformation being restricted at tectonic boundaries at its eastern and western margins, without significant gravitational spreading.

International audience; We present the most extensive and up-to-date unified GPS velocity field for Iran. We processed the data collected during 10 yr (2006–2015) from the Iranian Permanent GNSS Network (IPGN) and combined them with previously published velocity solutions from the GPS survey measurements during 1997–2013. We analysed this velocity field using a continuum approach to compute a new strain-rate map for this region and we designed a block model based on the main geological, morphological and seismic structures. Comparison between both approaches suggests similar results and allows us to present the first comprehensive first-order fault-slip-rate estimates for the whole of Iran. Our results confirm most of the results from previous geodetic studies. However, we also show a trade-off between the coupling ratio of the Iranian Makran subduction interface and the kinematics of the faults north of the Makran in the Jazmurian depression. Indeed, although too scarce to accurately estimate a coupling ratio, we show that coupling higher than 0.4 on the plate interface down to a depth of 25 km will induce extension on the E–W faults in the Jazmurian region. However, the sites close to the shoreline suggest a low coupling ratio; hence, the coupling on this plate interface is probably more complicated than previously described and the Iranian Makran subduction interface mechanical behaviour might be similar to that on the Hellenic subduction zone.

The switch in direction of convergence between Central Iran and the Eurasian Plate is believed to have a significant impact on the structural style in the Alborz Mountains, in the north of Iran. To understand the deformation pattern and investigate the influence of the South Caspian Basin kinematics since the middle Miocene on the structural styles and active tectonics of the Alborz Mountains, a series of scaled analogue models were prepared, in which passively layered loose sand simulating the sedimentary units were subjected to orthogonal and subsequently oblique shortening by a rigid indenter. Model results indicate that during the shortening, an arcuate-shaped foreland-vergent imbricate stack forms in front of the indenter. The orthogonal shortening is characterized by a prevailing right-lateral and left-lateral oblique-slip motion in the east and west of the model, respectively. This shift in kinematics contradicts the proposed preneotectonic (orthogonal) model of the Alborz. However, during oblique shortening, model results show that deformation is mainly accommodated by left-lateral transpression within the sand wedge and internal deformation. Oblique shortening is consistently accommodated by continued left-lateral motion on the west-northwest-trending oblique thrusts, whereas the east–west-trending thrusts and the preexisting east-northeast-trending right-lateral oblique thrusts reactivate as left-lateral oblique faults. Precise monitoring of the model surface also illustrates partitioning of shortening into the foreland-vergent left-lateral thrusting in the south and hinterland-vergent back thrusting in the north. These model results are generally consistent with field observations and GPS data of structure and kinematics of the Alborz Mountains.

We use historical and recent major earthquakes and GPS geodetic data to compute seismic strain rate, geodetic slip deficit, static stress drop, the parameters of the magnitude–frequency distribution and geodetic strain rate in the Iranian Plateau to identify seismically mature fault segments and regions. Our analysis suggests that 11 fault segments are in the mature stage of the earthquake cycle, with the possibility of generating major earthquakes. These faults primarily are located in the north and the east of Iran. Four seismically mature regions in southern Iran with the potential for damaging strong earthquakes are also identified. We also delineate four additional fault segments in Iran that can generate major earthquakes without robust clues to their maturity.The most important fault segment in this study is the strike-slip system near the capital city of Tehran, with the potential to cause more than one million fatalities.

Defining the structural style of fold-and-thrust belts is an important step for understanding the factors that control their long- and short-term dynamics, for comprehending seismic hazard associated with them, and for assessing their economic potential. While the thin-skinned model (no basement involvement) has long been the driving methodology for cross section construction and restoration of foreland fold-and-thrust belts, a wealth of new geological and geophysical studies have shown that they are often thick-skinned, that is, basement-involved.

A series of scaled analogue models are used to study (de)coupling between basement and cover deformation. Rigid basal blocks were rotated about a vertical axis in a ‘bookshelf’ fashion, which caused strike-slip faulting along the blocks and in the overlying cover units of loose sand. Three different combinations of cover–basement deformations are modelled: (i) cover shortening before basement fault movement; (ii) basement fault movement before cover shortening; and (iii) simultaneous cover shortening with basement fault movement. Results show that the effect of the basement faults depends on the timing of their reactivation. Pre- and syn-orogenic basement fault movements have a significant impact on the structural pattern of the cover units, whereas post-orogenic basement fault movement has less influence on the thickened hinterland of the overlying belt. The interaction of basement faulting and cover shortening results in the formation of rhombic structures. In models with pre- and syn-orogenic basement strike-slip faults, rhombic blocks develop as a result of shortening of the overlying cover during basement faulting. These rhombic blocks are similar in appearance to flower structures, but are different in kinematics, genesis and structural extent. We compare these model results to both the Zagros fold-and-thrust belt in southwestern Iran and the Alborz Mountains in northern Iran. Based on the model results, we conclude that the traces of basement faults in cover units rotate and migrate towards the foreland during regional shortening. As such, these traces do not necessarily indicate the actual location or orientation of the basement faults which created them.

Orogens may suffer more than one phase shortening resulting in superposition of structures of different generations. Superimposition of orthogonal or oblique shortening is studied using sandbox and ...

The preexisting north-south trending basement faults and their reactivation played an important role during the evolution of the Zagros fold-thrust belt. The Anaran basement fault in the Lurestan r ...

We used the focal mechanisms of crustal earthquakes (depth

Article history: We present a velocity field compiled from a network of 27 permanent and 20 campaign GPS stations across NE Iran. This new GPS velocity field helps to investigate how Arabia-Eurasia collision deformation is accommodated at the northern boundary of the deforming zone. The present-day northward motion decreases eastward from 11 mm/yr at Tehran (∼52 ◦ E) to 1.5 mm/yr at Mashhad (∼60 ◦ E). N-S shortening across the Kopeh Dagh, Binalud and Koh-e-Sorkh ranges sums to 4.5 ± 0. 5m m /yr at longitude 59 ◦ E. The available GPS velocities allow us to describe the rigid-body rotation of the South Caspian about an Euler pole that is located further away than previously thought. We suggest that two new stations (MAVT and MAR2), which are sited far from the block boundaries, are most likely to indicate the full motion of the South Caspian basin. These stations suggest that NW motion is accommodated by right-lateral slip on the Ashkabad fault (at a rate of up to 7 mm/yr) and by up to 4-6 mm/yr of summed left- lateral slip across the Shahroud left-lateral strike-slip system. Our new GPS results are important for assessing seismic hazard in NE Iran, which contains numerous large population centers and possesses an abundant historical earthquake record. Our results suggest that the fault zones along the eastern Alborz and western Kopeh Dagh may accommodate slip at much faster rates than previously thought. Fully assessing the role of these faults, and the hazard that they represent, requires independent verification of their slip-rates through additional GPS measurements and geological fieldwork.

[1] Two-dimensional thermal-mechanical models of thick-skinned, salt-based fold and thrust belts, such as the Zagros, SW Iran, are used to address: (1) the degree of deformation and decoupling between cover and basement rocks due to the presence of a weak salt detachment, (2) the reactivation potential of pre-existing basement normal faults due to brittle or ductile behavior of the lower crust (as related to cold or hot geothermal gradients), and (3) variations in deformation style and strain distribution. The geometry and kinematics of the orogenic wedge and the activity of pre-existing basement faults are strongly influenced by the geothermal gradient (defined by the Moho temperature, MT) and basement rheology. We infer that the MT plays a major role in how the lower and upper crust transfer deformation toward the foreland. In relatively hot geotherm models (MT = 600°C at 36 km depth), the lowermost basement deforms in a ductile fashion while the uppermost basement underlying the sedimentary cover deforms by folding, thrusting, and displacements along pre-existing basement faults. In these models, cover units above the salt detachment occur within a less deformed, wide plateau in the hinterland. In relatively cold geotherm models (MT = 400°C at 36 km depth), deformation is mainly restricted to basement imbricate thrusts that form within the orogenic hinterland. Detachment folding, thrusting, and gravity gliding occur within cover sediments above uplifted basement blocks. Gravity gliding contributes to a larger amount of shortening in the cover compared to the basement.

This study uses results from a series of analogue models, and field observations, scanned data and sections of natural landslides to investigate the kinematics and internal deformation during the failure of an unstable slope. The models simulate collapse of granular slopes and focus on the spatial and temporal distribution of their internal structures. Using a series of systematically designed models, we have studied the effect of friction and deformability of the runout base on internal deformation within a granular slope. The results of these different models show that the collapse of granular slopes resulted in different-generation extensional faults at the back of the slope, and contractional structures (overturned folds, sheath folds and thrusts) at the toe of the slope. The failure surfaces and the volume of the failure mass changed both spatially and temporally. Younger failure surfaces formed in the back of the older ones by incorporating additional new material from the head of the slope. Our model results also show that the nature of the runout base has a significant influence on the runout distance, topography and internal deformation of a granular slope. Model results are compared with natural landslides where local profiles were dug in order to decipher the internal structures of the failure mass. The natural cases show similar structural distribution at the head and toe of the failure mass. As in model results, our field observations indicate the presence of at least two generations of failure surfaces where the older ones are steeper.

Systematic analog models are run to study the variation in deformation across basement steps in the Zagros fold-thrust belt. Our model results demonstrate that basement configuration/topography influences the sedimentation thickness and, hence, the kinematics and geometric evolution of the fold and thrust belt. The greater the difference in thickness between the adjacent cover units across a basement step, the sharper and clearer will be the offset of the deformation front. Based on model results, we conclude that in a fold-thrust belt, where basement step/topography is covered by a layer of ductile salt acting as a decollement, the effect of the salt decollement on the evolution of the belt is far greater than the effect of thickness variation of the cover units.

This contribution reviews our current understanding of the tectonic development of the Amerasia Basin and presents new analogue modelling results relating to its formation. The Amerasia Basin is se ...

The b value of the Gutenberg-Richter relation and the standard deviate, Z, were calculated to investigate the temporal and spatial variations in seismicity patterns associated with the September 10 ...

Scaled analog and numerical brittle–viscous shortening models are employed to evaluate how fold–thrust structures evolve with changes in the cohesion of brittle materials, a rather poorly constrained physical parameter at this scale of experiment. The shortening models are characterized by various styles of shear zones and features resembling pop-up structures. The kinematics, geometry, and number of these structures are controlled by the viscous detachment layers in the models; the finite deformation of the model wedges is fundamentally different in model sets with one or two viscous layers. We demonstrate that the structural evolution of the numerical models is very sensitive to small changes in cohesion value. This is especially pronounced in the experiments that incorporate two weak viscous layers. The overall deformation of the numerical models is most similar to analog models when cohesion values are 70–80 Pa.

We performed a quantitative comparison of brittle thrust wedge experiments to evaluate the variability among analogue models and to appraise the reproducibility and limits of model interpretation. Fifteen analogue modeling laboratories participated in this benchmark initiative. Each laboratory received a shipment of the same type of quartz and corundum sand and all laboratories adhered to a stringent model building protocol and used the same type of foil to cover base and sidewalls of the sandbox. Sieve structure, sifting height, filling rate, and details on off-scraping of excess sand followed prescribed procedures. Our analogue benchmark shows that even for simple plane-strain experiments with prescribed stringent model construction techniques, quantitative model results show variability, most notably for surface slope, thrust spacing and number of forward and backthrusts. One of the sources of the variability in model results is related to slight variations in how sand is deposited in the sandbox. Small changes in sifting height, sifting rate, and scraping will result in slightly heterogeneous material bulk densities, which will affect the mechanical properties of the sand, and will result in lateral and vertical differences in peak and boundary friction angles, as well as cohesion values once the model is constructed. Initial variations in basal friction are inferred to play the most important role in causing model variability. Our comparison shows that the human factor plays a decisive role, and even when one modeler repeats the same experiment, quantitative model results still show variability. Our observations highlight the limits of up-scaling quantitative analogue model results to nature or for making comparisons with numerical models. The frictional behavior of sand is highly sensitive to small variations in material state or experimental set-up, and hence, it will remain difficult to scale quantitative results such as number of thrusts, thrust spacing, and pop-up width from model to nature. Fil: Schreurs, Guido. University of Bern; Suiza Fil: Buiter, Susanne J. H.. University of Oslo; Noruega. Norges Geologiske Undersekelse; Noruega Fil: Boutelier, Jennifer. University of Toronto; Canadá Fil: Burberry, Caroline. Uppsala Universitet; Suecia Fil: Callot, Jean-Paul. Ifp Energies Nouvelles; Francia Fil: Cavozzi, Cristian. Università di Parma; Italia Fil: Cerca, Mariano. Universidad Nacional Autónoma de México; México Fil: Chen, Jian-Hong. National Taiwan University; República de China Fil: Cristallini, Ernesto Osvaldo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. Comisión Nacional de Investigación Científica y Tecnológica; Chile Fil: Cruden, Alexander R.. University of Toronto; Canadá Fil: Cruz, Leonardo. University of Stanford; Estados Unidos Fil: Daniel, Jean-Marc. Ifp Energies Nouvelles; Francia Fil: Da Poian, Gabriela. Universidad de Buenos Aires; Argentina Fil: Garcia, Victor H.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina Fil: Gomes, Caroline J. S.. Universidade Federal de Ouro Preto; Brasil Fil: Grall, Céline. Ifp Energies Nouvelles; Francia Fil: Guillot, Yannick. University Of Lille; Francia Fil: Guzman, Cecilia Griselda. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos ; Argentina Fil: Hidayah, Triyani Nur. State University of New Jersey; Estados Unidos Fil: Hilley, George. University of Stanford; Estados Unidos Fil: Klinkmüller, Matthias. University of Bern; Suiza Fil: Koyi, Hemin A.. Uppsala Universitet; Suecia Fil: Lu, Chia-Yu. National Taiwan University; República de China Fil: Maillot, Bertrand. Universite de Cergy-Pontoise; Francia Fil: Meriaux, Catherine. Monash University; Australia Fil: Nilfouroushan, Faramarz. Uppsala Universitet; Suecia Fil: Pan, Chang-Chih. National Taiwan University; Suecia Fil: Pillot, Daniel. Ifp Energies Nouvelles; Francia Fil: Portillo, Rodrigo. Universidad Nacional Autónoma de México; México Fil: Rosenau, Matthias. German Research Centre for Geosciences; Alemania Fil: Schellart, Wouter P.. Monash University; Australia Fil: Schlische, Roy W.. State University of New Jersey; Estados Unidos Fil: Take, Andy. Queens University; Canadá Fil: Vendeville, Bruno. Laboratoire D'oceanologie Et de Geosciences; Francia Fil: Vergnaud, Marine. Ifp Energies Nouvelles; Francia Fil: Vettori, Matteo. Università di Parma; Italia Fil: Wang, Shih-Hsien. National Taiwan University; República de China Fil: Withjack, Martha O.. State University of New Jersey; Estados Unidos Fil: Yagupsky, Daniel Leonardo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Yamada, Yasuhiro. Kyoto University; Japón