Slip Vectors Research Articles

The relationship between kinematics and fault geometry for surface coseismic ruptures on across-strike faults: New observations of slip vectors and displacements along the Pisia and Skinos faults from the 1981 Eastern Gulf of Corinth, Greece earthquakes

The relationships between kinematics and fault geometry for the coseismic ruptures from the 24th and February 25, 1981 earthquake sequence in the eastern Gulf of Corinth (Ms 6.7 and 6.4) are analysed. The two earthquakes ruptured faults located across strike rather than along strike as typifies other earthquake sequences. In detail, surface ruptures formed on the sub-parallel Pisia and Skinos Faults, with an 8 km along-strike overlap zone, separated across strike by < 2 km. The largest coseismic offsets occurred in the overlap zone. The 41-year-old ruptures are still well preserved as bedrock fault plane lichen-free stripes and colluvial ruptures, allowing detailed structural mapping at 213 rupture localities. A comparison between our measurements and Jackson et al. (1982) showed no overall consistent signal of post-seismic slip as some of our measurements were greater and some smaller than those recorded in 1981. The ruptures produced a single maximum asymmetric profile (Pisia: maximum throw of 223 cm) and a double maxima profile (Skinos: maximum throw of 109 cm and 130 cm). The shapes of the profiles differed in previous earthquakes on these faults, as evidenced by an older lichen-free stripe, implying non-characteristic earthquakes. Summing the two overlapping throw profiles across-strike reveals a single maximum symmetric bell-like profile. Using the above observations on coseismic offsets, kinematic information, and the geometry of faults, a rupture scenario has been proposed in terms of fault bends and corrugation orientations which suggests that parts of each fault may have ruptured in each earthquake.

GEODETIC EVIDENCE FOR POST-SEISMIC DEFORMATIONS FOLLOWING THE 2014 NORTH AEGEAN MW 6.9 EARTHQUAKE

The 2014 North Aegean Sea earthquake was a strong (Mw 6.9) event that caused significant crustal deformations. In the present study we investigate the long-term impact of the earthquake on the kinematics of the North Aegean Trough (NAT). For this purpose, we analyzed GPS observations collected from May 2010 to April 2022 at five permanent GPS reference stations. Two of these stations are located close to the epicenter(s) on the Islands of Lemnos and Samothrace. We processed the data using the Precise Point Positioning (PPP) technique. The analysis of the obtained coordinate time-series revealed a post-seismic deformation (PSD) period lasting for more than two years leading to cumulative 2D post-seismic displacement of 22 mm and 27 mm for Samothrace and Lemnos, respectively. The magnitudes of these post-seismic slip vectors correspond to 23% and 49% of the co-seismic vectors at Samothrace and Lemnos, respectively. The long-term analysis showed that after the end of the PSD period the stations are characterized by stable velocities that are noticeably different compared to the velocities prior to the event. We observed a change in the velocity in the order of 2 mm/yr for both Samothrace and Lemnos. It is the first time that PSD and velocity changes have been reported for the 2014 North Aegean Sea earthquake shedding light on the characteristics and the impact of this important earthquake on the kinematics of NAT.

Rapid acquisition of digital fingerprints of Ti-6Al-4V macrotexture from machining force measurement data

Titanium alloys display anisotropic deformation properties due to the hexagonal close-packed (hcp) crystal structure of the α-phase. When subjected to localised deformation during machining, this behaviour influences fluctuations in the cutting force response of the material as the tool encounters grains of different orientations. In this research, cutting force signals acquired during face turning of Ti–6Al–4V possessing a lamellar α colony structure have been spatially mapped demonstrating the ability to identify microstructural features such as prior-β grain boundaries, grain boundary α, and α colonies. Measured cutting forces have been correlated to texture using orientation information acquired from large area EBSD analysis. A relationship between the misalignment of the crystallographic a slip vector with respect to the cutting direction and the passive cutting force response has been established, demonstrating a rise in cutting forces as this misalignment is increased. This novel approach to in-process materials evaluation offers manufacturers the potential of a powerful digital quality assurance tool, with the results presented here demonstrating the possibility for rapid characterisation of entire component surfaces, revealing microstructural features, and inferring the crystallographic orientation of macrotextured regions in Ti–6Al–4V.

Quantitative determination of fault slip magnitude: a review

In geology, a fault is a rock fracture with perceptible relative displacement of the opposite sides of the fracture. Quantitatively obtaining the activity history of faults depends mainly on the estimation of fault slip and the study of markers, which can be used to understand and analyze the tectonic evolution of the faulted regions. Fault slip is calculated by restoring points that were originally adjacent before the deformation, those points are named piercing points. In this paper, we review some published methods to determine fault slip, using: (1) the offset of contours on structural contour maps; (2) offset on seismic reflection sections; (3) a known slip vector (fault striae) and one marker; (4) two known markers. Cases (3) and (4) are commonly applied to field work and geological maps.

The Geometry and Kinematics of the Latest Paleozoic Allatoona Fault, One of the Youngest Thrusts in the Southernmost Appalachian Hinterland, Alabama and Georgia, U.S.A.

The Allatoona thrust fault in the southernmost hinterland of the Appalachian Blue Ridge-Piedmont megathrust sheet is among the latest structures in the kinematic sequence of events along the west flank of the orogen. It is an out-of-sequence, craton-directed thrust fault that cuts metamorphic isograds and earlier thrusts, and it has a nearly linear trace of ≥280 km, making it one of the major thrust faults in the orogen. On the northwest, the fault cuts Pennsylvanian or younger(?) regional cross antiforms that cause significant orogenic curvature of older underlying thrust sheets and is likely Permian in age. To the southeast, however, units within the fault hanging wall maintain a nearly constant width resulting in a significant change in the regional structural architecture of the orogen. In the central segment of the fault, where it marks the western/eastern Blue Ridge domain boundary, a ~20 km-long eyelid window (Mulberry Rock window) framed by three amphibolite facies thrust sheets overlying the greenschist facies Talladega belt allochthon, allows a 3-D view into the structural architecture, kinematics, and trajectories of the regional thrusts. Two earlier thrusts within the window (Mulberry Rock and Burnt Hickory Ridge thrusts, with a combined minimum horizontal net slip component of 27 km) are cut by the Allatoona fault, which is a ~15 m-wide high strain zone with top-to-the-northwest displacement, and a &gt;17.2 km horizontal net slip vector. Structural branch points between the Allatoona and Mulberry Rock thrusts indicate that the Mulberry Rock allochthon is a large north-trending horse beneath the Allatoona fault, centered on the Mulberry Rock window, which is likely the result of oblique ramp thrusting over the massive Mulberry Rock Gneiss. The Allatoona fault cuts down obliquely into the tectonostratigraphy progressively deeper both to the northeast and northwest, locally approaching underlying foreland thrust sheets, and cutting older regional structures. To the northeast, the Allatoona fault lies at the base of the Dahlonega gold belt, becoming an internal eastern Blue Ridge thrust at Dawsonville, Georgia. Although that sequence extends another 120 km into North Carolina, continuation of the Allatoona fault that additional distance is in debate. Regardless, the Allatoona is one of the kinematically latest and longest faults in the southern Appalachian orogen.

Seismotectonics of the Blanco Transform Fault System, Northeast Pacific: Evidence for an Immature Plate Boundary

AbstractAt the Blanco transform fault system (BTFS) off Oregon, 138 local earthquakes and 84 double‐couple focal mechanisms from ocean‐bottom‐seismometer recordings jointly discussed with bathymetric features reveal a highly segmented transform system without any prominent fracture zone traces longer than 100 km. In the west, seismicity is focused at deep troughs (i.e., the West and East Blanco, and Surveyor Depressions). In the east, the BTFS lacks a characteristic transform valley and instead developed the Blanco Ridge, which is the most seismically active feature, showing strike‐slip and dip‐slip faulting. Sandwiched between the two main segments of the BTFS is the Cascadia Depression, representing a short intra‐transform spreading segment. Seismic slip vectors reveal that stresses at the eastern BTFS are roughly in line with plate motion. In contrast, stresses to the west are clockwise skewed, indicating ongoing reorganization of the OTF system. As we observed no prominent fracture zones at the BTFS, plate tectonic reconstructions suggest that the BTFS developed from non‐transform offsets rather than pre‐existing transform faults during a series of ridge propagation events. Our observations suggest that the BTFS can be divided into two oceanic transform systems. The eastern BTFS is suggested to be a mature transform plate boundary since ∼0.6 Ma. In contrast, the western BTFS is an immature transform system, which is still evolving to accommodate far‐field stress change. The BTFS acts as a natural laboratory to yield processes governing the development of oceanic transform faults.

Complex 3‐D Surface Deformation in the 1971 San Fernando, California Earthquake Reveals Static and Dynamic Controls on Off‐Fault Deformation

AbstractThe shallow 1971 MW6.6 San Fernando, California earthquake involved a complex rupture process on an immature thrust fault with a non‐planar geometry, and is notable for having a higher component of left‐lateral surface slip than expected from seismic source models. We extract its 3‐D coseismic surface displacement field from aerial stereo photographs and document the amount and width of the vertical and fault trace‐parallel components of distributed deformation along strike. The results confirm the significant left‐lateral surface offsets, suggesting a slip vector rotation at shallow depths. Comparing our offsets against field measurements of fault slip, we observe that most of the offset was accommodated in the damage zone, with off‐fault deformation averaging 69% in both the fault trace‐parallel and vertical components. However, the magnitude and width of off‐fault deformation behave differently between the vertical and fault trace‐parallel components, which, along with the rotation in rake near the surface, can be explained by dynamic rupture effects.

New Insights Into Crustal Deformation of the Indonesia–Australia–New Guinea Collision Zone From a Broad‐Scale Kinematic Model

AbstractThe Indonesia‐Australia‐New Guinea collision zone comprises a complex system of tectonic blocks whose relative motion accommodates convergence of the Sunda Block, Pacific, Australian, and Philippine Sea plates. Previous studies have considered either the western or eastern ends of this system, in eastern Indonesia and Papua New Guinea, respectively. However, these studies had limited ability to characterize either the kinematics of the central part of the system or transitions in tectonic regime across it. In this study, we perform a simultaneous inversion of 492 earthquake slip vectors and 267 GPS velocities to quantify the block movement spanning the Sunda‐Banda Arc, Western New Guinea, and Papua New Guinea. Our best‐fitting kinematic block model comprises 23 elastic blocks, for which we estimate the rotation rates and block boundary slip rates. We show how the Cenderawasih Bay sphenochasm was likely formed by a combination of both rotations (2.82 ± 0.11°/Myr anticlockwise) of the Bird's Head Block and southwest‐directed convergence (39.9 ± 1.7 mm/yr) along the Lowlands fault. Our estimated relative slip vectors across the New Guinea Fold‐and‐Thrust Belt indicate a transition in the tectonic regime of the block boundary from predominately thrust faulting at its western segment, with a convergence rate up to 19.5 ± 0.6 mm/yr, to predominately sinistral motion in the center segment with slip rate ∼7 mm/yr, and returning to thrust in the eastern segment with a convergence rate up to 9.0 ± 0.5 mm/yr, implying the combined effect of multiple driving mechanisms.

Geometric Control on Seismic Rupture and Earthquake Sequence Along the Yingxiu‐Beichuan Fault With Implications for the 2008 Wenchuan Earthquake

AbstractThe 2008 Mw 7.9 Wenchuan earthquake is the most disastrous seismic event in China since 1976. Both field and seismological investigations suggest a multi‐stage coseismic rupture with most damage associated with the Yingxiu‐Beichuan Fault (YBF) of spatially variable fault strike and dip angles. To investigate the effect of fault geometric complexity on coseismic rupture and paleoseismic pattern on the YBF, we perform earthquake sequence modeling on 3D fault geometry in the framework of rate‐and‐state friction law. Our model produces a long‐term earthquake sequence with quasi‐regular recurrences of whole‐fault ruptures and segmented ruptures. The along‐strike rupture segmentation, earthquake propagation speed, and slip rate are mainly controlled by along‐strike variations of fault dip and strike angles. Particularly, the YBF can be divided into two segments: the southern segment featured by large events (Mw &gt; 8.0) and the northern segment with smaller events (Mw &lt; 7.5), with recurrence intervals primarily determined by the tectonic loading rate. In a whole‐rupture event, the rupture speed mainly correlates with the fault dip angle; a smaller dip angle results in a wider seismogenic zone and higher rupture speeds, whereas the small‐scale variation in rupture speed is regulated by the fault strike angle. The effect of strike variation on the total coseismic slip amount is more pronounced due to the large strike angle gradient along the YBF. After varying the slip vector to reflect the northward transition from the dominant thrust‐slip to strike‐slip faulting during the Wenchuan coseismic rupture, we obtain reasonably good agreement of model simulated coseismic surface displacements with GPS observations.

Fault Friction Derived From Fault Bend Influence on Coseismic Slip During the 2019 Ridgecrest Mw 7.1 Mainshock

AbstractThe variation of stress on faults is important for our understanding of fault friction and the dynamics of earthquake ruptures. However, we still have little observational constraints on their absolute magnitude, or their variations in space and in time over the seismic cycle. Here we use a new geodetic imaging technique to measure the 3D coseismic slip vectors along the 2019 Ridgecrest surface ruptures and invert them for the coseismic stress state. We find that the coseismic stresses show an eastward rotation that becomes increasingly transtensional from south‐to‐north along the rupture, that matches the known background stress state. We find that the main fault near the Mw 7.1 mainshock hypocenter was critically stressed. Coseismic slip was maximum there and decreased gradually along strike as the fault became less optimally oriented due its curved geometry. The variations of slip and stress along the curved faults are used to infer the static and dynamic fault friction assuming Mohr‐Coulomb failure. We find shear stresses of 4–9 MPa in the shallow crust (∼1.3 km depth) and that fault friction drops from a static, Byerlee‐type, value of 0.61 0.14 to a dynamic value of 0.29 0.04 during seismic slip. These values explain quantitatively the slip variations along a transpressional fault bend.

Tools to analyse misleading kinematic interpretations of faults offsetting inclined or folded surfaces: Applications to Asturian Basin (NW Iberian Peninsula) examples

When working with geological maps and cross-sections, and no kinematic criteria on fault motion are available, we usually classify the type of fault (dip-slip, strike-slip, oblique) according to the observed separation of planar markers, usually bedding. Although in many cases the separation agrees with fault slip, and therefore, the deduced type of fault is correct, these deductions can be completely wrong in certain circumstances. Amongst other parameters, the observed separation depends on the angular relationship between the cut-off line of the planar marker on the fault plane and the slip vector. In this paper, we elaborate on this relationship and present a tool to facilitate classifications of faults whose motion does not involve rotation of the fault blocks, and cut and offset previously tilted or folded surfaces. This tool consists of graphs that predict how the observed separation will be in cross sections and maps. In addition, the influence of different parameters on the magnitude of the separation in a geological section across a fault is discussed. The validity of the presented tool is demonstrated through its application to two field examples of strike-slip faults offsetting inclined layers and a fold train in the Asturian Basin. Our graphs can be used to improve geological interpretations, in a predictive way when constructing geological maps and cross-sections, and to decipher the existence of layers tilted or folded before fault development.

Monitoring the slip of helical wires in a flexible riser under combined tension and bending

When a flexible pipe is subjected to combined tension and bending, the helical wires in the external tension armour layer are most failure prone. Understanding the true relative slippage of helical wires is very important to accurately predict the mechanical behaviour of flexible risers under complex loads. This study proposes a monitoring method for the relative slippage of helical wires in flexible risers under combined tension and bending, using three-dimensional digital image correlation technology. For the flexible riser test specimen with an internal diameter of 8 inches, a four-point quasi-static test was carried out, and full-field displacement vectors of helical wires marked by a range of scattered spots were accurately monitored. Thereafter, the relative slip character of the helical wires is obtained by processing the measurement data. The results indicate that the measured relative slip vectors are essentially tangential to the surface of the internal cylinder, while the measured total slip distances and angles are compared with the results from the existing theoretical model and the good agreement is achieved, thus verifying the correctness of the measurement method. Additionally, the laws of slip responses, such as the total slip distance, slip direction, and slip components along the axial and lateral wire directions, of helical wires in flexible risers are investigated, and the slip responses of the helical wire under different axial tensions are discussed.

Giant sheath-folded nappe stack demonstrates extreme subhorizontal shear strain in an Archean orogen

Abstract Giant sheath-folded nappes are associated with suture zones and emplacement of far-traveled allochthons in Phanerozoic orogens, demonstrating a rare but significant geologic phenomenon indicative of modern-style plate tectonics. We document the world's oldest-known subhorizontal mega-scale sheath fold from Archean Alpine-style nappes of the Central orogenic belt, North China craton. The Zanhuang nappes are recumbent Alpine-style forearc-affinity metabasaltic and metasedimentary nappes emplaced over a passive continental margin in the Archean, marking an ancient suture zone. Field evidence shows multiscale sheath folds from decimeters to tens of meters in size, and our three-dimensional fence profile, fold hinges, kinematic lineations, and lithological traces define an ~1-km-long (parallel to the x-axis) sheath fold in the core of the nappe stack. Structural analysis statistically demonstrates the macro-scale recumbent sheath-folded nappe preserves a complete 180° hinge-line curvature. The giant sheath fold plunges northwest, reflecting its formation during non-coaxial, top-to-the-southeast shearing with extremely high shear strain (γ ≥10), equated to &amp;gt;10 km of ductile slip on the bounding surfaces. Slip vectors derived from S-C fabrics on overturned limbs are consistent with rotation into the southeast-directed transport direction, parallel to the similarly rotated fold hinges. Comparison of the giant sheath-folded nappes from the Archean Zanhuang example with mega-scale sheath folds in Phanerozoic and Proterozoic orogens shows that Neoarchean lithosphere was stiff enough to allow tectonics to operate in a manner analogous to modern-style plate tectonics.

COMPARISON OF MODERN GEODYNAMIC MODES OF FRAMING OF THE EUROASIAN LITHOSPHERIC PLATE

The purpose of the work is to analyze the modern geodynamic mode of framing of the Eurasian lithospheric plate to determine the types of deformations in the structures of spreading, subduction and rift genesis and favorable conditions for oil and gas formation at certain stages of structure development. The authors have analyzed the Arctic spreading zone, the Kamchatka subduction zone, the southwestern part of Eurasia and the Baikal rift system. The author's development of calculation of slip vectors of rock masses in foci of earthquakes and methods of tensor analysis of mechanics of fractured media were used in the work. Differences and similarities between the Arctic spreading zone, the Kamchatka subduction zone, the southwestern part of Eurasia and the Baikal rift system are shown. All of the above structures have a complex layered-block structure. That is, in a layered-block medium in layers, and in individual blocks and in time, the stress-strain state of the lithosphere changes, which directly depends on the direction of the axes of compressive stresses

New insight into the 24 January 2020, Mw 6.8 Elazığ earthquake (Turkey): An evidence for rupture-parallel pull-apart basin activation along the East Anatolian Fault Zone constrained by Geodetic and Seismological data

In this study, we investigated the main features of the causative fault of the 24 January 2020, Mw 6.8 Elazığ earthquake (Turkey) using seismological and geodetic data sets to provide new insight into the East Anatolian Fault Zone (EAFZ). We first constrained the co-seismic surface deformation and the rupture geometry of the causative fault segment using Interferometric Synthetic Aperture Radar (InSAR) interferograms (Sentinel-1A/B satellites) and teleseismic waveform inversion, respectively. Also, we determined the centroid moment tensor (CMT) solutions of focal mechanisms of the 27 aftershocks using the regional waveform inversion method. Finally, we evaluated the co-seismic slip distribution and the CMT solutions of the causative fault as well as of adjacent segments using the 27 focal solutions of the aftershocks, superimposed on the surface deformation pattern. The CMT solution of the 24 January 2020Elazığ earthquake reveals a pure strike-slip focal mechanism, consistent with the structural pattern and left-lateral motion of the EAFZ. The rupture process of the Elazığ event indicated that the rupture is started at 12 km around the hypocenter, and then propagated bilaterally along the NE-SW but mainly toward the southwest. The rupture slip has initially propagated toward the southwest (first 10 s) and northeast (4 s), and again toward the southwest (9 s). Maximum displacement is calculated as 1.3 m about 20 km southwest of the hypocenter at 6 km depth (centroid depth). The rupture stopped to down-dip around 20 km depth toward the southwest. The distribution of the slip vectors indicates that the rupture continued mostly through a normal oblique movement. Most of the moment release was released SW of the hypocenter and the rupture reached up to around 50 km. The focal mechanisms of analyzed 27 aftershocks show strike-slip, but mostly normal and normal oblique-slip faulting with an orientation of the tensional axes (NNE-SSW), indicating a normal oblique-slip, “transtensional” stress regime, parallel-subparallel to the strike of the EAFZ, consistent with SW-rupture directivity and co- seismic deformation pattern. Finally, based on the co-seismic surface deformation compatible with the distributional pattern of normal focal solutions, normal and normal oblique-slip focals of the aftershocks evidence the rupture-parallel pull-apart basin activation as a segment boundary of the left-lateral strike-slip movement of the EAFZ.

A taxonomy of grain boundary migration mechanisms via displacement texture characterization

Atomistic simulations provide the most detailed picture of grain boundary (GB) migration currently available. Nevertheless, extracting unit mechanisms from atomistic simulation data is difficult because of the zoo of competing, geometrically complex 3D atomic rearrangement processes. In this work, we introduce the displacement texture characterization framework for analyzing atomic rearrangement events during GB migration, combining ideas from slip vector analysis, bicrystallography and optimal transportation. Two types of decompositions of displacement data are described: the shear-shuffle and min-shuffle decomposition. The former is used to extract shuffling patterns from shear coupled migration trajectories and the latter is used to analyze temperature dependent shuffling mechanisms. As an application of the displacement texture framework, we characterize the GB geometry dependence of shuffling mechanisms for a crystallographically diverse set of mobile GBs in FCC Ni bicrystals. Two scientific contributions from this analysis include 1) an explanation of the boundary plane dependence of shuffling patterns via metastable GB geometry and 2) a taxonomy of multimodal constrained GB migration mechanisms which may include multiple competing shuffling patterns, period doubling effects, distinct sliding and shear coupling events, and GB self diffusion.

Evaluating 9 m of near-surface transpressional displacement during the Mw 7.8 2016 Kaikōura earthquake: re-excavation of a pre-earthquake paleoseismic trench, Kekerengu Fault, New Zealand

ABSTRACT During the Kaikōura earthquake, a paleoseismic trench was dextrally displaced ∼9 m and shortened by 1.3 ± 0.4 m – the largest globally recorded displacement of a trench. Analysis showed that two processes accommodated subequal amounts of slip at the surface: (1) discrete dextral-slip on two steeply-dipping faults bounding a <3.5 m wide central deformation zone; and (2) coseismic clockwise rotation of turf rafts and pervasive sediment deformation in that zone. The second (successive) process resulted in upward (<1 m) and outward (<2 m) bulging along low-angle thrusts, creating horizontal fault-perpendicular shortening that exceeds the heave (∼1.3 m). This discrepancy results from coseismic rotation of rafts, that shorten upon approaching perpendicularity with the fault – creating extra apparent shortening (in fault-orthogonal view). Comparison of pre- and post-earthquake trench logs indicates that strike-slip ruptures at the same site can be expressed differently over time; fault strands carrying major displacement in 2016 were not the locus of deformation in the previous earthquake(s), suggesting temporal unpredictability is important in defining fault zones. The last several paleoearthquakes at the trench produced cm-dm scale normal-sense dip separations across faults; however, the 2016 earthquake created compressive structures including up-bulging and low-angle reverse faulting, as well as fissuring. This contrast in deformation style likely resulted from an >8° clockwise rotation of the local slip vector in 2016 (becoming transpressive), highlighting that small changes in slip kinematics may affect rupture zone structures.

Revisiting the Source Rupture Process of the Mainshock of the 2016 Kumamoto Earthquake and Implications for the Generation of Near-Fault Ground Motions and Forward-Directivity Pulse

ABSTRACT Strong near-fault ground motions associated with the MJMA 7.3 mainshock of the 2016 Kumamoto, central Kyushu, Japan, earthquake sequence have received attention by seismological and engineering communities. In this study, the kinematic source rupture process was reanalyzed based on an improved approach for the representation of source faults. The slips at densely distributed point sources were defined via the bilinear interpolation of those at surrounding control points. The result shows that the rupture started on the Hinagu fault with a small initial rupture and propagated beyond the junction to the Futagawa fault. The rupture on the Futagawa fault mainly propagated up and northeastward. A large slip area with a peak slip of 4.9 m and peak slip velocity of 3.1 m/s was detected at depths ranging from 3 to 15 km in the central part of the Futagawa fault. This asperity spatially coincides with a body with moderate-seismic velocity (VP∼6 km/s) and low-seismic attenuation. The slips on the Futagawa fault have significant normal-slip components, whereas the slip vectors of the Hinagu fault represent almost pure right-lateral strike slip. The shallower part of the fault segments in the western Aso caldera is characterized by relatively large normal slips. The estimated slip-velocity functions at shallower depths (&amp;lt;3 km) are almost temporally symmetric and relatively long. The shallower portion of the source fault significantly contributes to the velocity and displacement waveforms at near-fault sites. On the contrary, the slip-velocity functions at deeper depths (&amp;gt;3 km) are temporally asymmetric and have a sharp peak. The simulation of the ground-motion evolution suggests that the lateral flow in the Aso Valley was primarily triggered by the strong forward-directivity pulse generated from the asperity on the Futagawa fault.

The inferences on the Aegean geodynamic context from 30 October 2020 Samos earthquake (Mw:6.8)

On October 30, 2020, an earthquake with a magnitude of 6.8 (Mw) struck the northern coast of Samos Island in the Kuşadası Gulf. The solution to the focal mechanism indicates that the earthquake of 30 October 2020 occurred on a normal fault with nodal planes of E-W strike; thus, indicating extension in N-S direction. The fault plane solutions show a N-S trending extension for normal faults, which are obtained by inverting the moment tensor waveforms of 23 earthquakes and the P-wave first motion polarities of 11 aftershocks. A normal fault stress regime of approximately N-S (N6°E) σ3 axis is given by the inversion of slip vectors measured at sites located on land in Kuşadası. The mean R value is 0.84, suggesting that the stress regime is triaxial extensional stress state. The inversion of the focal mechanism of earthquakes occurring on land and in the Gulf of Kuşadası describes an extensional stress regime active today, characterized by an approximately N-S (N9°E) σ3 axis. The calculated R value of 0.31 indicates a triaxial stress state. For the 30 October 2020 earthquake (Mw:6.8), the Coulomb failure stress change analysis shows a substantial reduction in stress in the N-S direction supporting the kinematic results. The N-S extension in Western Anatolia-Aegean is largely influenced by the relatively fast movement of the Hellenic trench southwards, related to the sinking of the African plate beneath Aegean.

Reconfigurable Slip Vectoring Control in Four In-Wheel Drive Electric Vehicles

Controllability, maneuverability, fault-tolerance/isolation and safety are significantly enhanced in electric vehicles (EV) equipped with the redundant actuator configuration of four-in-wheel electric motors (4IWM). A highly reconfigurable architecture is proposed and illustrated for the adaptive, nonmodel-based control of 4IWM-EVs. Given the longitudinal force, yaw-moment requests and the reconfiguration matrix, each IWM is given a slip reference according to a Slip Vectoring (SV) allocation strategy, which minimizes the overall slip vector norm. The distributed electric propulsion and the slip vector reference allow for a decentralized online estimation of the four-wheel torque-loads, which are uncertain depending on loading and road conditions. This allows for the allocation of four different torques depending on individual wheel conditions and to determine in which region (linear/nonsaturated or nonlinear/saturated) of the torque/slip characteristics each wheel is operating. Consequently, the 4IWMs can be equalized or reconfigured, including actuator fault-isolation as a special case, so that they are enforced to operate within the linear tire region. The initial driving-mode selection can be automatically adjusted and restored among eighteen configurations to meet the safety requirements of linear torque/slip behavior. Three CarSim realistic simulations illustrate the equalization algorithm, the quick fault-isolation capabilities and the importance of a continuous differential action in a critical double-lane-change maneuver.