Elastic Block Research Articles

Disaggregated Cloud Memory with Elastic Block Management

With the growing importance of in-memory data processing, cloud service providers have launched large memory virtual machine services to accommodate memory intensive workloads. Such large memory services using low volume scaled-up machines are far less cost-efficient than scaled-out services consisting of high volume commodity servers. By exploiting memory usage imbalance across cloud nodes, disaggregated memory can scale up the memory capacity for a virtual machine in a cost-effective way. Disaggregated memory allows available memory in remote nodes to be used for the virtual machine requiring more memory than its locally available memory. It supports high performance with the faster direct memory while satisfying the memory capacity demand with the slower remote memory. This paper proposes a new hypervisor-integrated disaggregated memory system for cloud computing. The hypervisor-integrated design has several new contributions in its disaggregated memory design and implementation. First, with the tight hypervisor integration, it investigates a new page management mechanism and policy tuned for disaggregated memory in virtualized systems. Second, it restructures the memory management procedures and relieves the scalability concern for supporting large virtual machines. Third, exploiting page access records available to the hypervisor, it supports application-aware elastic block sizes for fetching remote memory pages with different granularities. Depending on the degrees of spatial locality for different regions of memory in a virtual machine, the optimal block size for each memory region is dynamically selected. The experimental results with the implementation integrated to the KVM hypervisor, show that the disaggregated memory can provide on average 6 percent performance degradation compared to the ideal local-memory only machine, even though the direct memory capacity is only 50 percent of the total memory footprint.

Bounding the Moment Deficit Rate on Crustal Faults Using Geodetic Data: Application to Southern California

AbstractThe interseismic moment deficit rate (MDR) constrains the potential for future moment release in earthquakes. Published estimates of the geodetic MDR in Southern California vary by a factor of 3 depending on the type of forward model, method of estimation, and data quality. It is our aim to determine to what degree these discrepancies may be explained by quantifying the uncertainty for a given class of forward models, accounting for data errors and limited model resolution. We apply a new method, the Constrained Optimization Bounding Estimator, to bound the MDR in Southern California using geodetic data and an elastic plate‐block model. Total MDR ranges from 1.3 to 2.0 × 1019 N m/yr, equivalent to one MW 8.17–8.31 over 160 years, higher than the observed seismic moment since 1850. This observation, together with published estimates of off‐fault moment rate, could imply that significant permanent (inelastic) deformation is taking place in Southern California or that future earthquakes will make up the difference. Uncertainty in MDR from Constrained Optimization Bounding Estimator using a single model is comparable to the range of published MDR estimates using elastic block models but about a factor of 8 smaller than the range of all published models. Thus, the choice of forward model dominates theuncertainty in MDR for Southern California. While additional data would be helpful for constraining the MDR, as much or more effort is needed to quantify the prediction errors associated with a given model and to develop observations that narrow the possible range of forward models under consideration.

Crustal Deformation of the Altyn Tagh Fault Based on GPS

AbstractKnowledge of the slip behavior of the Altyn Tagh fault (ATF) has significant implications for our understanding of the tectonic deformation of the Tibetan Plateau. In this study, we process Global Positioning System (GPS) data spanning 2009–2017 across the western ATF, merge the solution with recently published GPS velocities, and obtain a dense GPS velocity field for northern Tibet. We introduce an elastic block model and estimate the fault slip rate, interseismic fault coupling (ISC), and seismic moment accumulation rate along the ATF. The estimated left‐lateral strike‐slip rate of the ATF decreases eastward from 12.8 ± 0.4 mm/a to 0.1 ± 0.2 mm/a. Results show a heterogeneous distribution of ISC along the fault, with the fault locking depth varying from 5 to 20 km. The seismic moment accumulation rate is 2.16–2.37 × 1018 N m/km along three segments between Sulamu Tagh and Aksay bends, where the accumulated seismic moment over the last five centuries could be balanced by earthquakes with magnitudes of Mw 7.7, Mw 7.6, and Mw 7.8, respectively. We calculate the ratio of the Indo‐Eurasia convergence accommodated by the ATF and find that 10.3% of the convergence is accommodated along the fault by lateral extrusion; quantitative analysis of the strain rate, however, shows that a large part of the northern Tibet is not well described by elastic block rotation. Consequently, we suggest that a hybrid kinematic model that includes both block‐like and continuous deformation is needed to better delineate the crustal deformation of the Tibetan Plateau.

Fault Slip Rates and Seismic Moment Deficits on Major Faults in Ordos Constrained by GPS Observation

The Ordos Block, surrounded by numerous active faults, is a relatively rigid but dangerous area with many strong historical earthquakes. We derive the block rotation velocity and fault slip rates in this area by using GPS data recorded from 1999 to 2007 and implementing an elastic block model. Instead of assuming vertical faults, as did most previous studies in and around Ordos, we use an improved method to invert for the fault dip angles and construct a closed 3-D fault system in our inversion. The predicted slip rates range from <1 mm/yr to ~ 10 mm/yr. Our results are roughly consistent with geological and other geodetic observations. Using the estimated slip rates, we also calculate the cumulative seismic moment due to fault locking and the released moment from historical earthquake catalogues. A comparison of the two quantities indicates that the Hetao Rift has an unreleased seismic moment equal to a Mw 7.9 earthquake, which is also indicated by frequent earthquakes above M6 after 1900.

Theory of pressure acoustics with viscous boundary layers and streaming in curved elastic cavities.

The acoustic fields and streaming in a confined fluid depend strongly on the viscous boundary layer forming near the wall. The width of this layer is typically much smaller than the bulk length scale set by the geometry or the acoustic wavelength, which makes direct numerical simulations challenging. Based on this separation in length scales, the classical theory of pressure acoustics is extended by deriving a boundary condition for the acoustic pressure that takes viscous boundary-layer effects fully into account. Using the same length-scale separation for the steady second-order streaming, and combining it with time-averaged short-range products of first-order fields, the usual limiting-velocity theory is replaced with an analytical slip-velocity condition on the long-range streaming field at the wall. The derived boundary conditions are valid for oscillating cavities of arbitrary shape and wall motion, as long as both the wall curvature and displacement amplitude are sufficiently small. Finally, the theory is validated by comparison with direct numerical simulation in two examples of two-dimensional water-filled cavities: The well-studied rectangular cavity with prescribed wall actuation, and a more generic elliptical cavity embedded in an externally actuated rectangular elastic glass block.

Observation on the clinical efficacy of closed reduction and block compression Kirschner wire technique in the treatment of fresh bony Mallet finger

Objective To explore the surgical technique and treatment outcomes of closed reduction and block compression Kirschner wire technique in the treatment of fresh bony Mallet finger. Methods From June 2012 to May 2015, 20 cases of fresh bony Mallet finger were treated with close reduction and Kirschner wire fixation. One Kirschner wire was used to fix the avulsed fracture fragment with elastic block compression and the other wire kept the distal interphalangeal (DIP) joint in extension. The two wires were pressurized each other through the end of the hook. The pressure device between the Kirschner wires was disengaged 3 weeks after the operation. The Kirschner wires were removed 6 to 7 weeks postoperatively. Then the functional exercises were strengthened. Results All the patients obtained anatomical reduction and bony union. The follow-up time ranged from 6 to 24 months with an average of 10.5 months. According to the Patel’s evaluation method, the results were graded as excellent in 11 cases, good in 7 cases and fair in 2 cases. Conclusion The treatment of fresh bony Mallet fractures with closed reduction and block compression Kirschner wire technique is a simple procedure that provides stable internal fixation and good recovery with less complications. Key words: Finger injuries; Treatment outcome; Bony Mallet finger; Kirschner wire

Static and sliding contact of rough surfaces: Effect of asperity-scale properties and long-range elastic interactions

Friction in static and sliding contact of rough surfaces is important in numerous physical phenomena. We seek to understand macroscopically observed static and sliding contact behavior as the collective response of a large number of microscopic asperities. To that end, we build on Hulikal et al. (2015) and develop an efficient numerical framework that can be used to investigate how the macroscopic response of multiple frictional contacts depends on long-range elastic interactions, different constitutive assumptions about the deforming contacts and their local shear resistance, and surface roughness. We approximate the contact between two rough surfaces as that between a regular array of discrete deformable elements attached to a elastic block and a rigid rough surface. The deformable elements are viscoelastic or elasto/viscoplastic with a range of relaxation times, and the elastic interaction between contacts is long-range. We find that the model reproduces the main macroscopic features of evolution of contact and friction for a range of constitutive models of the elements, suggesting that macroscopic frictional response is robust with respect to the microscopic behavior. Viscoelasticity/viscoplasticity contributes to the increase of friction with contact time and leads to a subtle history dependence. Interestingly, long-range elastic interactions only change the results quantitatively compared to the meanfield response. The developed numerical framework can be used to study how specific observed macroscopic behavior depends on the microscale assumptions. For example, we find that sustained increase in the static friction coefficient during long hold times suggests viscoelastic response of the underlying material with multiple relaxation time scales. We also find that the experimentally observed proportionality of the direct effect in velocity jump experiments to the logarithm of the velocity jump points to a complex material-dependent shear resistance at the microscale.

Present-day crustal deformation and strain transfer in northeastern Tibetan Plateau

The three-dimensional present-day crustal deformation and strain partitioning in northeastern Tibetan Plateau are analyzed using available GPS and precise leveling data. We used the multi-scale wavelet method to analyze strain rates, and the elastic block model to estimate slip rates on the major faults and internal strain within each block. Our results show that shear strain is strongly localized along major strike-slip faults, as expected in the tectonic extrusion model. However, extrusion ends and transfers to crustal contraction near the eastern margin of the Tibetan Plateau. The strain transfer is abrupt along the Haiyuan Fault and diffusive along the East Kunlun Fault. Crustal contraction is spatially correlated with active uplifting. The present-day strain is concentrated along major fault zones; however, within many terranes bounded by these faults, intra-block strain is detectable. Terranes having high intra-block strain rates also show strong seismicity. On average the Ordos and Sichuan blocks show no intra-block strain, but localized strain on the southwestern corner of the Ordos block indicates tectonic encroachment.

On the load dependence of friction: Role of the long-range elastic coupling

Abstract When an elastic block is squeezed in contact with a substrate the contact will in general consist of many asperity contact regions. During sliding the long-range elastic coupling between the contact regions have a big influence on the sliding dynamics: when the loading force increases the density of contact regions increases, which affects the lateral coupling between the contact region, and introduces a dependence of the friction force on the loading force. Here we present a full three-dimensional model study of the role of the elastic coupling on the friction force. The theory is applied to rubber friction, but the mechanism for the dependence of the friction coefficient on the load is relevant for non-rubber materials as well.

Numerical Study of Stresses around Holes Drilled and Filled by Expansive Cement: Case of Isotropic Linear Elastic Block of Rock

This work dealt with an essential problem of fragmentation of rocks with expansive cement. The redistribution and magnitude of stresses and displacement generated around holes were done by using Ansys Inc. Code which is based on finite element code. Blocks of rock with one hole, two holes, and nine holes drilled in square mesh and staggered mesh have been considered. Numerical results reveal that many factors can influence the mechanism of fragmentation of a rock by using expansive cement: hole diameter, hole spacing, panel mesh, expansive pressure applied, and the elastic properties of the massif. Stresses and displacements generated globally decrease when spacing holes increase. Normal stresses allow a better stress interaction between holes in the case of square mesh disposition. Staggered mesh disposition generates higher stresses than the square mesh disposition. But the square mesh disposition can be useful for controlled fragmentation in order to obtain block of rock with square geometry. For each expansive cement and rock, there exist suitable range of diameter and spacing hole which can generate high stresses for breaking the rock.

Elastic block and strain modeling of GPS data around the Haiyuan-Liupanshan fault, northeastern Tibetan Plateau

Based on the dense GPS velocity field in the northeastern margin of the Tibetan Plateau from 1999 to 2016, we have produced the deformation and strain characteristics of the Haiyuan fault and the Liupanshan fault. Estimated long-term slip rate along the Haiyuan-Liupanshan fault zones show a gradual decrease from 6.4 ± 1.6 mm/yr at the Tuolaishan fault to 2.9 ± 1.2 mm/yr at the Southern Liupanshan fault. Left-lateral thrusting movement was inverted for the Xiangshan-Tianjingshan fault (XS-TJS), which has an average slip rate of 2.1 ± 3.4 mm/yr during the study period. We also calculated the heterogeneous distribution of interseismic coupling along the fault zones. Our result also shows the locking depth of the Tianzhu seismic gap is ∼22 km. The slip rate deficit, the seismic moment accumulation rate, and the Coulomb stress accumulation rate are high on the fault planes, whereas the second invariant of the strain rate is low at the surface. The Liupanshan fault is locked to a depth of ∼23 km, and the corresponding seismic moment accumulation rate on the fault plane is high, while the strain rate at the surface is low. The accumulated strain along the Tianzhu seismic gap and the Liupanshan fault could be balanced by earthquakes with magnitudes of Mw7.9 and Mw7.4, considering the absence of large earthquakes over the last 1000 years and 1400 years respectively. The Haiyuan segments had ruptured during 1920 Haiyuan earthquake, and the estimated locking depth for period 1999–2016 is 5–10 km. Its seismic moment accumulation rate at depth is low and the strain rate at the surface is high. Our result indicates that 70% of the strike-slip along the Haiyuan segments transforms into thrusting along the Liupanshan fault, while the remaining 30% is related to the orogeny of the Liupanshan. For slip between the Haiyuan fault and the XS-TJS, about 27–34% of the slip is partitioned on the XS-TJS.

Hydrogel-embedded nanocrystalline hydroxyapatite granules (elastic blocks) based on a cross-linked polyvinylpyrrolidone as bone grafting substitute in a rat tibia model.

PurposeThe aim of this study was to examine the in vivo characteristics and levels of integration and degradation of a ready-to-use bone grafting block with elastic properties (elastic block) for the use in surgery.Materials and methodsThirty-six male Wistar rats underwent surgical creation of a well-defined bone defect in the tibia. All created defects – one per animal – were filled with an unsintered nanocrystalline hydroxyapatite embedded either with a non-cross-linked hydrogel carrier (CONT, n=18) or a cross-linked hydrogel carrier (elastic block [EB], n=18) based on polyvinylpyrrolidone (PVP) and silica sol, respectively. The animals were killed after 12 (n=12), 21 (n=12) and 63 days (n=12). The bone formation and defect healing were quantified by histomorphometric measurements made in paraffin sections. Additionally, immunohistochemical (tartrate-resistant acid phosphatase [TRAP] and alkaline phosphatase [aP]), antibody-based examinations (CD68) and energy-dispersive x-ray scattering measurements of silica atom concentration were carried out.ResultsA larger remaining bone defect area overall was observed in EB after 12 days and 21 days. After 63 days, similar areas of remaining bone defects were found. The amount of the remaining carrier material in EB overall was higher at all times. In CONT no residual carrier material was found at 12 days and later. CD68 analyses showed significantly lower level of CD68-positive marked cells after 21 days in CONT, and nonsignificant differences at 12 and 63 days, respectively. Additionally, a significantly higher level of aP-positive marked cells was observed in CONT after 12 days. Later on, the levels of aP-positive marked cells were slightly higher in EB (21 and 63 days). Furthermore, no significant differences regarding the level of TRAP-positive marked cells in each group were observed.ConclusionThe bone substitute (EB) with the cross-linked PVP-based hydrogel carrier leads at the beginning to a higher amount of remaining carrier material and remaining bone substitute. This delayed degradation is supposed to be the reason for the observed lower level of bone remodeling and is caused by the irradiation changes (cross links) in the structure in PVP.

Present-day kinematics in the Eastern Mediterranean and Caucasus from dense GPS observations

The Eastern Mediterranean and Caucasus are located among the Eurasian, African and Arabian plates, and tectonic activities are very complex. In this paper, the kinematics and strain distribution in these regions are determined and investigated from dense GPS observations with over 1000 stations and longer observations. The elastic block model is used to constrain present-day plate motions and crustal deformation. The relative Euler vectors between the Nubian, Arabian, Caucasus, Anatolian and Central Iranian plates are estimated. The Arabian-Eurasia, Anatolian-Eurasia, Nubian-Eurasia, Caucasus-Eurasia and Central Iranian Euler vectors are 0.584±0.1Myr−1, 0.825±0.064Myr−1, 0.35±0.175Myr−1, 0.85±0.086Myr−1 and 0.126±0.016Myr−1. The strain rate in the East Mediterranean and Caucasus has been estimated from the GPS velocity field. The results show that the thrust dominated areas, the eastern Mediterranean-Middle East-Caucasus and Zagros have negative dilatation and the western Anatolia region has positive 2D dilatation rate with significant rotation. The west Anatolian shows the extension in NW-SE with about 150–199nstrain/yr in the W-E direction. The Central Anatolia shows compression rate below 50nstrain/yr and extensional strain rate adjacent to East Anatolian Fault and Dead Sea Fault is about 0–100nstrain/yr. The contraction strain rate is higher in Zagros and Caucasus between 100–150nstrain/yr and contraction orientation is along the NE-SW direction in Caucasus. The north part of Iran shows less contraction rate below 50nstrain/yr but North-East Zagros Mountains, Tabriz fault and Chalderan fault show extensional rate between 50–110nstrain/yr and principal axes rotation in the N-S direction. The maximum contraction observed in the Kopek Dag is about 100–194nstrain/yr and orientated in the NE-SW direction. East Zagros Mountain and Makran subduction zone have a large clockwise rotation with 70–85nradian and principal axes remains mostly along the N-S direction. The observed extension is along N-S by about 0–100nstrain/yr with counter clockwise rotation in Dead Sea Fault. The Sinai block shows shortening rate in the range of 0–100nstrain/yr.

Mechanical and acoustic emission characteristics of rock: Effect of loading and unloading confining pressure at the postpeak stage

The disturbance caused by excavation to surrounding rock structures during underground mining under complex geological conditions at great depth induces rock failure due to the effect of stress concentration and unloading. Therefore, the design, construction and maintenance of structures (i.e., pillars, drifts, chambers) are based not only on peak strength, but also on postpeak behavior and, subsequently, residual strength of rocks. Therefore, better understanding the characteristic features of rock at the postpeak stage is of paramount importance for underground construction and ground support design activities. Argillaceous limestone specimens loaded to the residual phase in the conventional triaxial compression test under different initial confining pressures were continuously loaded by loading and unloading cycles. Analysis of the variation characteristics of stress and strain were complemented with acoustic emission (AE) monitoring for investigating the effects of the confining pressure and the loading and unloading cycles on the mechanical properties of the rock in the residual phase. Besides, the yielding premonition information about the rock in the loading confining pressure stage was analyzed and calculated. The results show that because the deformation during the axial loading mainly comes from the sliding between the fracture planes, the bearing capacity is related to not only the confining pressure, but also the unloading path; the elastic modulus in the axial elastic deformation stage is larger than the corresponding elastic modulus of the prepeak stage, and the axial deformation presents good feature of elastic–plastic deformation; the bearing capacity of rock in the residual phase was provided by the frictional sliding between the elastic rock block under confining pressure. The precursor information about the rock yielding to plastic deformation in the loading confining pressure test of the failure rock could be confirmed based on the evolution characteristics of the AE amplitude.

Wrinkle surface instability of an inhomogeneous elastic block with graded stiffness

Surface instabilities have been studied extensively for both homogeneous materials and film/substrate structures but relatively less for materials with continuously varying properties. This paper studies wrinkle surface instability of a graded neo-Hookean block with exponentially varying modulus under plane strain by using the linear bifurcation analysis. We derive the first variation condition for minimizing the potential energy functional and solve the linearized equations of equilibrium to find the necessary conditions for surface instability. It is found that for a homogeneous block or an inhomogeneous block with increasing modulus from the surface, the critical stretch for surface instability is 0.544 (0.456 strain), which is independent of the geometry and the elastic modulus on the surface of the block. This critical stretch coincides with that reported by Biot (1963 Appl. Sci. Res. 12 , 168–182. ( doi:10.1007/BF03184638 )) 53 years ago for the onset of wrinkle instabilities in a half-space of homogeneous neo-Hookean materials. On the other hand, for an inhomogeneous block with decreasing modulus from the surface, the critical stretch for surface instability ranges from 0.544 to 1 (0–0.456 strain), depending on the modulus gradient, and the length and height of the block. This sheds light on the effects of the material inhomogeneity and structural geometry on surface instability.

Out-of-plane load–displacement model for two-way spanning masonry walls

This paper describes a methodology for modelling the nonlinear, inelastic load–displacement behaviour of two-way spanning unreinforced masonry walls subjected to out-of-plane loading. The model utilises a simplified macroblock approach that starts with the assumption of a collapse mechanism based on the wall’s boundary conditions. It then treats the wall as having zero tensile strength and assumes that the resistance comes entirety from two gravity-based resistance components: elastic rigid block rocking, and inelastic friction, with the total load resistance of the wall taken as the sum of these individual components. Analytical expressions for calculating the load and displacement capacities of the elastic rocking component of response are derived from the principles of statics using an integration approach well suited for the treatment of two-way mechanisms. Expressions for the associated frictional capacity component are obtained using the virtual work method. Comparison of the theoretical load–displacement response with experimentally measured data is favourable as demonstrated using data obtained via quasistatic cyclic tests on two-way spanning walls; the model is shown to provide an acceptable lower bound estimate of actual behaviour. The developed approach could be used to construct pushover curves for a range of different collapse mechanisms and therefore has the potential to be assimilated into a simplified displacement-based seismic design/assessment technique for two-way spanning walls against out-of-plane collapse.

The kinematics of crustal deformation in Java from GPS observations: Implications for fault slip partitioning

Our understanding of seismic risk in Java has been focused primarily on the subduction zone, where the seismic records during the last century have shown the occurrence of a number of tsunami earthquakes. However, the potential of the existence of active crustal structures within the island of Java itself is less well known. Historical archives show the occurrence of several devastating earthquake ruptures north of the volcanic arc in west Java during the 18th and the 19th centuries, suggesting the existence of active faults that need to be identified in order to guide seismic hazard assessment. Here we use geodetic constraints from the Global Positioning System (GPS) to quantify the present day crustal deformation in Java. The GPS velocities reveal a homogeneous counterclockwise rotation of the Java Block independent of Sunda Block, consistent with a NE–SW convergence between the Australian Plate and southeast Asia. Continuous GPS observations show a time-dependent change in the linear rate of surface motion in west Java, which we interpret as an ongoing long-term post-seismic deformation following the 2006 Mw 7.7 Java earthquake. We use an elastic block model in combination with a viscoelastic model to correct for this post-seismic transient and derive the long-term inter-seismic velocity, which we interpret as a combination of tectonic block motions and crustal faults strain related deformation. There is a north–south gradient in the resulting velocity field with a decrease in the magnitude towards the North across the Kendeng Thrust in the east and the Baribis Thrust in the west. We suggest that the Baribis Thrust is active and accommodating a slow relative motion between Java and the Sunda Block at about 5±0.2 mm/yr. We propose a kinematic model of convergence of the Australian Plate and the Sunda Block, involving a slip partitioning between the Java Trench and a left-lateral structure extending E–W along Java with most of the convergence being accommodated by the Java megathrust, and a much smaller parallel motion accommodated along the Baribis (∼5±0.2 mm/yr) and Kendeng (∼2.3±0.7 mm/yr) Thrusts. Our study highlights a correlation between the geodetically inferred active faults and historical seismic catalogs, emphasizing the importance of considering crustal fault activity within Java in future seismic assessments.

Earthquake Potential of Active Faults in Taiwan from GPS Observations and Block Modeling

Research Article| October 19, 2016 Earthquake Potential of Active Faults in Taiwan from GPS Observations and Block Modeling Wu‐Lung Chang; Wu‐Lung Chang aDepartment of Earth Sciences, National Central University, 300, Zhongda Road, Taoyuan 32001, Taiwanwuchang@ncu.edu.tw Search for other works by this author on: GSW Google Scholar Kuo‐En Ching; Kuo‐En Ching bDepartment of Geomatics, National Cheng Kung University, 1, University Road, Tainan 701, Taiwan Search for other works by this author on: GSW Google Scholar Chiou‐Hsien Lee; Chiou‐Hsien Lee aDepartment of Earth Sciences, National Central University, 300, Zhongda Road, Taoyuan 32001, Taiwanwuchang@ncu.edu.tw Search for other works by this author on: GSW Google Scholar Yi‐Rui Lee; Yi‐Rui Lee cSinotech Engineering Consultants, Inc., 14F, 171, Section 5, Nanking E. Road, Taipei 105, Taiwan Search for other works by this author on: GSW Google Scholar Chi‐Fang Lee Chi‐Fang Lee aDepartment of Earth Sciences, National Central University, 300, Zhongda Road, Taoyuan 32001, Taiwanwuchang@ncu.edu.tw Search for other works by this author on: GSW Google Scholar Seismological Research Letters (2016) 87 (6): 1274–1286. https://doi.org/10.1785/0220160094 Article history first online: 14 Jul 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Wu‐Lung Chang, Kuo‐En Ching, Chiou‐Hsien Lee, Yi‐Rui Lee, Chi‐Fang Lee; Earthquake Potential of Active Faults in Taiwan from GPS Observations and Block Modeling. Seismological Research Letters 2016;; 87 (6): 1274–1286. doi: https://doi.org/10.1785/0220160094 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySeismological Research Letters Search Advanced Search ABSTRACT Taiwan is located at the boundary between the Philippine Sea plate and the passive continental margin of the Eurasian plate and is one of the most seismically active regions in the world. In an attempt to evaluate the seismogenic potential of active faults in Taiwan, we separated the region into 34 blocks with 27 known active faults as their boundaries and employed a 3D elastic block modeling method to invert the Global‐Positioning‐System‐measured surface deformation for block rotations and the fault coupling. Additional constraints from an up‐to‐date dataset of geologic fault‐slip rates were introduced to reconcile the discrepancy between the geodetically and geologically determined long‐term slip rates. Our results show that the Hsinhua fault and the southern part of the Longitudinal Valley fault may be weakly coupled near the surface and therefore experience shallow creeping in the interseismic period. The slip‐deficit rates, which relate to how fast the elastic strain is accumulated on faults, are relatively low (0.8–2.2 mm/yr) for faults in northern Taiwan compared with up to 4 mm/yr in the Western foothill of the central and southwestern Taiwan. Evaluations of earthquake potential based on our new modeling results indicate that the frontal thrust and the westernmost branch faults of central Taiwan and the northern Longitudinal Valley fault of eastern Taiwan are capable of generating Mw 6.0–7.3 earthquakes in the next few decades. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Tensile Instability in a Thick Elastic Body.

A range of instabilities can occur in soft bodies that undergo large deformation. While most of them arise under compressive forces, it has previously been shown analytically that a tensile instability can occur in an elastic block subjected to equitriaxial tension. Guided by this result, we conducted centimeter-scale experiments on thick elastomeric samples under generalized plane strain conditions and observed for the first time this elastic tensile instability. We found that equibiaxial stretching leads to the formation of a wavy pattern, as regions of the sample alternatively flatten and extend in the out-of-plane direction. Our work uncovers a new type of instability that can be triggered in elastic bodies, enlarging the design space for smart structures that harness instabilities to enhance their functionality.

Fault locking and slip rate deficit of the Haiyuan-Liupanshan fault zone in the northeastern margin of the Tibetan Plateau

GPS-derived horizontal velocities, geologic fault slip rates and earthquake-derived fault slip vector azimuths are inverted simultaneously for fault coupling and slip rate deficit on the Haiyuan-Liupanshan fault in the northeastern margin of the Tibetan Plateau. Along the Haiyuan fault, the results show 3.2–6.2mm/yr of left-lateral strike-slip, and the strike-slip transformed into thrusting deformation (2.8–3.5mm/yr) along the Liupanshan fault. The results suggest full coupling down to ∼10km along the Haiyuan fault. Significant portions from the Jinqianghe fault to the Maomaoshan fault, however, are locked to ∼23km depth. The abrupt change in fault coupling coincides with the Tianzhu seismic gap. High slip rate deficit (3.0–4.5mm/yr) and seismic moment accumulation rate are also interpreted along the seismic gap. The Liupanshan fault is locked to 15–20km depth. A high seismic moment accumulation rate, low slip rate deficit (2.0–3.2mm/yr) and scarcity of large seismic event over the last 1400 years may imply high strain accumulation on the fault. The results demonstrate that crustal deformation in the northeastern Tibetan Plateau is dominated by elastic block rotation. We also conclude that deformation due to fault coupling is limited along the near-field (less than 50km with velocities less than 2mm/yr) of the Haiyuan-Liupanshan fault.