Establishing genetic links between active shallow faulting and deep seismogenic sources is challenging, especially in areas where seismogenic faults lack clear and readily interpretable geological evidence at the surface. The architecture of the Pedeapenninic margin of the Northern Apennines (Italy) reflects a regional-scale and complex NE-verging blind thrust system, which is dissected by transpressive/transtensive faults resulting from active NE-SW orogenic compression. The local geological framework is defined by allochthonous ocean-derived units resting atop Pliocene-to-present successions exposed along the Northern Apennines margin and to the NE of it, while the innermost chain sector mostly contains Adria-related units. We present results from field structural-geological investigations to identify and characterize potential active faults along the margin. There, the Pliocene-to-present units are faulted and folded, indicating that tectonic activity is still on-going, thus contributing to the local seismic hazard. Top-to-the NE and SW normal faults are common in the area and deform the Pliocene-to-present succession together with NE-SW strike-slip and transpressional/transtensional faults. Based on field evidence, we define four potentially active thrust segments affecting Middle Pleistocene to Holocene deposits exposed along the margin. Calcite U-Th dating on samples from faults extend the most recent datable tectonic activity back to the Middle Pleistocene. Paleostress analysis from inversion of fault-slip data from the most recent identified striated fault planes constrains a NE-SW shortening direction parallel to the Apennines regional migration direction. A distinct but coaxial extensional stress regime, recorded by structures measured within Plio-Pleistocene formations, was also identified. Our results offer a sound starting point for future investigations aimed at improving our understanding of active and seismogenic faulting in the area, so as to create robust Probabilistic Seismic and Fault Displacement Hazard Assessment (PSHA and PFDHA) models that can implement refined seismic hazard maps benefitting from structural-geological deterministic inputs in addition to the classic seismological constraints.

BackgroundTsunamis are rare events compared to other disasters but have devastating consequences. In the last 100 years, more than 24 tsunamis and more than 235,000 fatalities have occurred globally. Indonesia has a high risk of a tsunami disaster. Since the devastating 2004 tsunami in the Indian Ocean, much research and preparatory work have been done to reduce the impact of future tsunamis in Indonesia, including in the province of Aceh, especially along the western coast where West Aceh is located. This coastal area was destroyed by a tsunami as high as 15–30 m, resulting in the loss of life, housing, tourist areas, industrial areas, and other public facilities. Given that tsunami disasters are rare and sometimes occur long in advance, human memory and awareness are reduced, making research on the level of tsunami awareness of disasters a challenging task.MethodProbabilistic Tsunami Hazard Assessment (PTHA) is a method that has been developed to predict tsunami hazards with a return period of hundreds to thousands of years, beyond the limited availability of historical data. The PTHA method can provide important information that supports tsunami risk management measures. This study aims to estimate recurrence period-based tsunami risk on the west coast of the district of Aceh Besar using the PTHA method. In this study, the source of the tsunami is caused by fault activity at sea. Seven tsunami scenarios based on fault parameters (earthquakes of magnitudes Mw 8.0 to 9.2 with interval 0,2) with the fault location focusing on the Aceh-Andaman Mega Thrust Segment, as applied in this study. This segment was a similar source to the 2004 Indian Ocean tsunami that created a rupture area along a distance of 1155 km, with six parts of the fault.ResultThe maximum inundation distance reached 6 km for the flat area, with a flow depth of 13 m. The site has a cliff that is close to the shoreline, with an inundation distance shorter than the distance across the flat area. With an arrival time of less than 25 min, it is recommended to have an evacuation building and evacuation road in a wide inundated area, and an arrangement of hills close to the beach as an evacuation area, in order to reduce the number of casualties. For 100 years return period or exceedance probability rate 0.01, the average flow depth on the coast may exceed 5 m, and the maximum flow depth for a 1000-year return period or annual probability of 0.001 is 12 m. With the potential tsunami in the future, continuous tsunami drills and tsunami education are needed so that people can maintain an awareness of the threat posed by tsunamis.

Abstract Active compressional tectonics along the outer front of the Apenninic-Maghrebian chain (Italy) is well documented along the northern and central segments and in Sicily. On the other hand, the Southern Apenninic Outer Front (SAOF) orogenic activity is well established only until the Lower-Middle Pleistocene. We address the hypothesis of its subsequent late Quaternary activity in central-southern Italy (Abruzzo and Molise regions). We integrated topographic and fluvial network analyses along with morphotectonic investigation of fluvial terraces to identify evidence of differential rock uplift. We compared the results with the main geolithological units, known structural elements, and long-term deformation history from seismic line interpretation. We found variable evidence suggesting localized rock uplift in the Abruzzo region along the SAOF (Abruzzo Citeriore Basal Thrust segment) and inward structures on its hanging wall (Casoli-Bomba high), as well as along part of the Struttura Costiera thrust. Middle-to-Late Pleistocene deformation is constrained by terrace tilting and disruption along the Pescara river. Localized shortening along segments of the Apenninic Outer Front could explain the observed pattern of anomalies which is difficult to explain with long-wavelength regional uplift alone. Our reconstruction is consistent with the long-term deformation of the area and agrees with its seismotectonic setting. Despite the low deformation rate context and the peculiar geological setting which challenges the interpretation of the topographic and geomorphic signals, this study compels reconsideration, in terms of seismic hazard assessment, of the existence of late Quaternary active thrusting in central-southern Italy.

Continental subduction below oceanic plates and associated emplacement of ophiolite sheets remain enigmatic chapters in global plate tectonics. Numerous ophiolite belts on Earth exhibit a far-travelled ophiolite sheet that is separated from its oceanic root by tectonic windows exposing continental crust, which experienced subduction-related high pressure-low temperature metamorphism during obduction. However, the link between continental subduction-exhumation dynamics and far-travelled ophiolite emplacement remains poorly understood. Here we combine data collected from ophiolite belts worldwide with thermo-mechanical simulations of continental subduction dynamics to show the causal link between the extrusion of subducted continental crust and the emplacement of far-travelled ophiolites. Our results reveal that buoyancy-driven extrusion of subducted crust triggers necking and breaking of the overriding oceanic upper plate. The broken-off piece of oceanic lithosphere is then transported on top of the continent along a flat thrust segment and becomes a far-travelled ophiolite sheet separated from its root by the extruded continental crust. Our results indicate that the extrusion of the subducted continental crust and the emplacement of far-travelled ophiolite sheets are inseparable processes.

On February 17, 1996, at 05:59:30 UTC there was an Mw 8.1 earthquake. Besides, it caused a tsunami. This event occurred in the northern part of the Cendrawasih Bay, where the New Guinea Thrust segment had a relatively low average slip velocity. To obtain a finite fault, waveforms from a tele-station located 30-90 degrees are used. The far-field body wave equation is used and inverted by the Kikuchi-Kanamori algorithm. In addition to obtaining source parameters, this study also aims to determine the value of the rupture velocity that occurs during coseismic events. From this research was found that the rupture velocity (vr) was 2.5 km/s, which occurred at a depth of 13.7 km. The largest value of vector slip is 2.31 m, with an average slip value of 0.922 m. The dimension area of the fault has a size of 272 km × 110 km. The seismic moment obtained is 1.5 × 1021 Nm, which is equivalent to Mw 8.1. This study also found a variance of 0.2844 in the use of the P and SH wave components, which is the smallest variance from the use of the P, P and SH, and SH components in the Kikuchi-Kanamori Program.

Growth of a thrust fault array in space and time: An example from the deep-water Niger delta

The article is the first part of a trilogy devoted to the study of post-rift deformations of the riftogenic structure of the Dnieper-Donets paleorift. The mechanisms of collision warping of the horizons of the sedimentary cover of the southeastern part of the Dnieper-Donets depression are considered. According to the previous mapping data, the tectonic deformations of the sedimentary cover were controlled by systems of faults of the north, north-west, and south-east vergence. The lattices of tectonites of the Hercynian, Lamaric, and Attic generations determine the specific “cross-thrust” structure of pushing. Overthrusts and linear folding of three generations permeate the sedimentary sequence of the transition zone from east to west for hundreds of kilometers within the eastern part of Izyumsky paleorift segment. The analytical base of the research was the materials of geological mapping of the zone of the junction of the depression with the Donets fold structure. Using field definitions of the tectonite vergency of the Hercynian, Laramide and Attic phases of tectogenesis, the original method of reconstruction of tectonic deformation fields and tectonophysics analysis of structures, collision deformations of the sedimentary cover of the south-eastern part of the Dnieper-Donets paleorift are studied. The tectonophysical analysis of tectonites of different ages indicates that together they control the cover-thrust and folded deformations of the riftogenic structure. Overthrusts and linear reverse-folding of three generations form the West-Donetsk integumentary-folding region, within which a segment of the same name tectonic thrust is distinguished. By pushing the system of repeatedly deformed, crushed into folds of geomass sedimentary rocks on weakly deployed syneclise deposits, the riftogenic structure of the south-eastern part of the basin is completely destroyed. The structural-tectonic framework of the allochthone, pushed from the side of the Donets structure, is composed of dynamically conjugated lattices of Hercynian, Laramide, and Attic tectonites. They control the echelon backstage of linear reverse-folds, tectonic plate-covers of transverse extrusion of sedimentary geomass from axial to airborne zones and folded covers of longitudinal thrust from the south-east. The riftogenic structure of the transition zone between the Dnieper-Donets basin and the Donets folded structure was completely destroyed by deformations of three generations of platform activation. The dynamically coupled tectonite lattice, the overlays, and the folded zones of the Hercynian, Laramide, and Attic generations jointly form the West-Donets fold-fold region within its boundaries. The main tectonic element of the area is the eponymous subregional tectonic thrust segment. The central structural zone is Veliko-Kamyshevakhskaya, Novotroitskaya, Druzhkovsko-Konstantinovskaya and Main anticlines. The central zone divides the body of the segment into two tectonic regions according to the tectonic style and intensity of deformation of the sedimentary sequence. The northern part is occupied by the Luhansk-Kamyshevakhsky region of the rocky-layered linear folding of the thrust, and the southern part is the Kalmius-Toretsky region of scaly tectonic covers.

Crust-mantle interaction inferred from the petrology and Sr-Nd-Pb isotope geochemistry of Eocene arc lavas from the Kahrizak Mountains, north-central Iran

U-Pb and Hf isotopes of detrital zircons from the Pongola Supergroup: Constraints on deposition ages, provenance and Archean evolution of the Kaapvaal craton

Analyzing structural variations along strike in a deep-water thrust belt

Abstract We analyze shallow (0–20 km) microseismicity adjacent to the Alpine Fault in New Zealand, where there is oblique convergence of the Australian and Pacific plates. Focal mechanisms for 155 earthquakes (June 2012 to October 2013) are inverted to determine the orientation of the stress field. This yields a principal horizontal axis of compression, SHmax = 114° ± 10°, which cannot be explained in terms of the sum of stress from tectonic loading due to plate convergence, indicated by GPS observations, and gravitational stresses. The azimuth of slip vectors for individual focal mechanisms cluster perpendicular and parallel to the plate convergence vector. These faults, however, strike at ~45° to SHmax from the stress inversion, suggesting a very low coefficient of friction. The earthquake slip directions may be kinematically controlled, accommodating the plate convergence on a limited set of fractures, similar to the segmentation for neotectonic faulting along the Alpine Fault, which is partitioned into strike‐slip and thrust segments at a 1–10 km scale. We suggest two possible controls on our calculated SHmax azimuths. First, there may be a slight clockwise bias in the estimates of SHmax from earthquakes; slip may be occurring on a more limited range of fractures than assumed by the stress inversion method, although this effect is likely to be relatively small (±5°). More importantly, the components of the stress field may be relieved at different timescales during big earthquakes, resulting in a residual stress field that varies significantly (±15°) on timescales of several large earthquakes.

ABSTRACTIn this work, trajectory optimisation has been performed for a wing-body rocket assisted vehicle to compute the bestset of performance parameters including burn-out angle, angle-of-attack, bank-angle and throttle command that would result in optimal down-range and cross-range performance of the re-entry vehicle. An hp-adaptive Pseudospectral method has been used for the optimisation by combining the launch and rocket rocket-assisted re-entry stages. The purpose of the research is to compute optimal burn-out condition, angle-of-attack, bank-angle and optimal thrust segments that would maximise the down-range and cross-range performance of the hypersonic boost glide vehicle, under constrained heat rate environments. The variation of down-range/cross-range performance of rocket rocket-assisted hypersonic boost glide vehicle with bounds on diminishing heat rate has also been computed.

Using laterally compatible cross sections to infer fault growth and linkage models in foreland thrust belts

Abstract Here we present the results of the inversion of a new geodetic data set covering the 2012 Emilia seismic sequence and the following 1 year of postseismic deformation. Modeling of the geodetic data together with the use of a catalog of 3‐D relocated aftershocks allows us to constrain the rupture geometries and the coseismic and postseismic slip distributions for the two main events (Mw 6.1 and 6.0) of the sequence and to explore how these thrust events have interacted with each other. Dislocation modeling reveals that the first event ruptured a slip patch located in the center of the Middle Ferrara thrust with up to 1 m of reverse slip. The modeling of the second event, located about 15 km to the southwest, indicates a main patch with up to 60 cm of slip initiated in the deeper and flatter portion of the Mirandola thrust and progressively propagated postseismically toward the top section of the rupture plane, where most of the aftershocks and afterslip occurred. Our results also indicate that between the two main events, a third thrust segment was activated releasing a pulse of aseismic slip equivalent to a Mw 5.8 event. Coulomb stress changes suggest that the aseismic event was likely triggered by the preceding main shock and that the aseismic slip event probably brought the second fault closer to failure. Our findings show significant correlations between static stress changes and seismicity and suggest that stress interaction between earthquakes plays a significant role among continental en echelon thrusts.

Active blind‐thrust systems pose hidden but destructive earthquake hazards in convergent mountain fronts around the world, exemplified by the most recent 2015 M w 6.4 Pishan event in the Hetian fold belt at the western Kunlun range front, northwest Tibetan plateau. Integrated analysis of surface geology, topography, seismic reflection profiles, and Pishan seismicity delineates the surface and subsurface geometries of the Hetian fold belt. Our results indicate that the fold belt is a segmented, active blind wedge thrust system. The Pishan event is generated by one wedge thrust segment along its leading edge: the mainshock is generated on the low‐angle fore‐thrust Slik ramp, and the aftershocks are diffusely distributed across the ramp, overlying anticline, and some unimaged structures beneath the ramp. Mapped sizes of other segments suggest that the fold belt is capable of much larger ( M w≥7.5) and more destructive earthquakes.

In 1255, 1344, and 1408 AD, then again in 1833, 1934, and 2015, large earthquakes, devastated Kathmandu. The 1255 and 1934 surface ruptures have been identified east of the city, along comparable segments of the Main Frontal Thrust (MFT). Whether the other two pairs of events were similar is unclear. Taking into account charcoal’s age inheritance, we revisit the timing of terrace offsets at key sites to compare them with the seismic record since 1200 AD. The location, extent, and moment of the 1833 and 2015 events imply that they released only a small part of the regional slip deficit on a deep thrust segment that stopped north of the Siwaliks. By contrast, the 1344 or 1408 AD earthquake may have ruptured the MFT up to the surface in central Nepal between Kathmandu and Pokhara, east of the surface trace of the great 1505 AD earthquake which affected western Nepal. If so, the whole megathrust system in Nepal broke in a sequence of earthquakes that lasted less than three centuries, with ruptures that propagated up to the surface from east to west. Today’s situation in the Himalayan seismic sequence might be close to that of the fourteenth century.

Impact of synkinematic sedimentation on the geometry and dynamics of compressive growth structures: Insights from analogue modelling

In the ultra-precision system, the multi-axis servo system is composed of air-core monopole linear motors (AMLM) for achieving nanopositioning. In the AMLM system, the thrust varies according to the changes of the relative position of motor's primary and secondary. In this paper, the concept of thrust stiffness is proposed in order to illustrate the phenomenon of varieties of thrust according to changes in position. By using the surface charge model, the air-gap magnetic flux density of AMLM is predicted. Based on this prediction, the whole winding's thrust, including straight and corner segments of winding, is calculated. Then, this winding thrust model is simplified to replace the original complicated analytical model. The accuracy of the simplified model is verified by the corresponding experimental tests. Thus, the thrust stiffness simplification model can be used in the feedforward compensation model in the control system of AMLM and efficiently decrease the calculation time of DSP.

Plate boundary deformation creates a south-easterly advancing, repetitive structural pattern in Canterbury dominated by the propagation of northeast-striking thrust assemblages. This pattern is regularly segmented by east-striking faults inherited from reactivated Cretaceous normal faults. The more evolved and deeply exposed structures in the foothills of north Canterbury provide insights into the tectonic processes of the blind structures now emerging from under the northern and eastern Canterbury Plains, where thrust and strike-slip fault activity are closely linked. The east-striking faults separate relative motion between thrust segments and accommodate oblique transpressive shear. Early stages of thrust emergence are dominated by anticlinal growth and blind, or partially buried, thrusts and backthrusts. The east-striking transecting faults therefore record timing of coseismic episodes of uplift and shortening with variable horizontal to vertical ratios and displacement rates on the hidden adjacent thrusts. The Greendale and blind Port Hills faults, with their associated aftershock patterns, are compatible with this style.

Lode-gold mineralization in convergent wrench structures: Examples from South Eastern Desert, Egypt