Uniform slip-rate along the Kunlun Fault: Implications for seismic behaviour and large-scale tectonics

Research on seismic behaviour of shear walls with high-strength steel is limited. A combined experimental and analytical investigation was conducted to assess seismic behaviour of flexure-dominant shear walls. A large-scale concrete shear wall with Grade 690 MPa (ASTM A1035) reinforcement and 84 MPa concrete was tested under simulated seismic loading. The wall was a ¼ -scale of a 6-storey shear wall, with 4.53 m height and 1.45 m length. It sustained a lateral drift of 1.8% prior to developing failure due to the rupturing of longitudinal reinforcement. This is 35% less than the drift capacity of a companion wall reinforced with 400 MPa reinforcement tested earlier. VecTor2 software was used to conduct an analytical parametric study to expand the experimental findings. The results indicate that the reinforcement grade has a significant impact on strength, ductility and hysteretic behaviour of shear walls.

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How to reveal the present-day mechanism of the 600 km long Doruneh fault in eastern Iran ?

10.5194/egusphere-egu2020-11110 ◽

2020 ◽

Author(s):

Fateme Khorrami ◽

Andrea Walpersdorf ◽

Zahra Mousavi ◽

Erwan Pathier ◽

Hamid Nankali ◽

...

Keyword(s):

Spatial Variability ◽

Large Scale ◽

Sand Dunes ◽

Slip Rate ◽

Seismic Velocities ◽

Slip Rates ◽

Radar Images ◽

Eastern Iran ◽

Spatial Coverage ◽

Satellite Radar

The enigmatic 600 km long E-W trending left-lateral Doruneh fault in eastern Iran is certified to be active by its well preserved geomorphological features all along its trace, but it is lacking recent seismic activity that could be attributed to its motion. Instead, the high seismogenic potential of the study zone is highlighted by the two M=7 earthquakes on the left-lateral E-W trending Dasht-e-Bayaz fault just south of Doruneh, in 1968 and 1979. Therefore, it remains important to understand the role of the Doruneh fault in the kinematics of the Arabia-Eurasia collision that takes place inside Iran&#8217;s political boundaries.Many different slip-rates have been estimated for the left-lateral motion of the Doruneh fault: 2.5 mm/yr by geomorphological marker offset dating, 1 mm/yr from preliminary GNSS measurements, and 5 mm/yr from a local InSAR study. &#160;These rather local estimates on the 600 km long fault highlight either temporal or spatial variability of the Doruneh present-day behavior. The spatial variability of the fault slip is still badly constraint as the western half of the fault is located in the Great Kavir desert. The analysis of satellite radar images was supposed to provide good constraints on the inter-seismic deformation with a full spatial coverage of the fault, especially thanks to the favorable E-W orientation of the Doruneh fault and the arid Iranian climate. However, decorrelation due to sand dunes and unexpected large tropospheric noise prohibited precise results from a first large-scale ENVISAT study, yielding an upper limit of the slip rate of 4 mm/yr. The high resolution SENTINEL-1 constellation (operational since 2014) is predicted to provide constraints on inter-seismic velocities down to 2 mm/yr from 2020 on. In complement, a dense GNSS survey has been conducted in 2012 and 2018 on a temporary network of 18 sites around a large part of the fault. This network densifies and completes the 17 permanent GNSS stations in up to 200 km distance to the fault trace situated mostly in the eastern, more populated part of the fault.In this work, we will point out our recent GNSS, InSAR and tectonic studies on the present-day characteristics of the Doruneh fault, to better understand the mechanism of this major fault in the kinematics of the Arabia-Eurasia collision, and to contribute to a better assessment of the seismic hazard in eastern Iran.

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Feasibility of Using Neural Networks to Obtain Simplified Capacity Curves for Seismic Assessment

Buildings ◽

10.3390/buildings8110151 ◽

2018 ◽

Vol 8 (11) ◽

pp. 151 ◽

Cited By ~ 6

Author(s):

João Estêvão

Keyword(s):

Neural Networks ◽

Large Scale ◽

Seismic Vulnerability ◽

Seismic Assessment ◽

Small Scale ◽

Eurocode 8 ◽

Seismic Behaviour ◽

Capacity Curves ◽

N2 Method ◽

Building Typology

The selection of a given method for the seismic vulnerability assessment of buildings is mostly dependent on the scale of the analysis. Results obtained in large-scale studies are usually less accurate than the ones obtained in small-scale studies. In this paper a study about the feasibility of using Artificial Neural Networks (ANNs) to carry out fast and accurate large-scale seismic vulnerability studies has been presented. In the proposed approach, an ANN was used to obtain a simplified capacity curve of a building typology, in order to use the N2 method to assess the structural seismic behaviour, as presented in the Annex B of the Eurocode 8. Aiming to study the accuracy of the proposed approach, two ANNs with equal architectures were trained with a different number of vectors, trying to evaluate the ANN capacity to achieve good results in domains of the problem which are not well represented by the training vectors. The case study presented in this work allowed the conclusion that the ANN precision is very dependent on the amount of data used to train the ANN and demonstrated that it is possible to use ANN to obtain simplified capacity curves for seismic assessment purposes with high precision.

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The heuristic vulnerability model: fragility curves for masonry buildings

Bulletin of Earthquake Engineering ◽

10.1007/s10518-021-01063-7 ◽

2021 ◽

Author(s):

Sergio Lagomarsino ◽

Serena Cattari ◽

Daria Ottonelli

Keyword(s):

Large Scale ◽

Fragility Curves ◽

Expert Elicitation ◽

Total Risk ◽

Seismic Behaviour ◽

Ground Acceleration ◽

Intensity Measures ◽

Bull Earthquake ◽

Damage Scenarios ◽

Vulnerability Model

AbstractIn the framework of seismic risk analyses at large scale, among the available methods for the vulnerability assessment the empirical and expert elicitation based ones still represent one of most widely used options. In fact, despite some drawbacks, they benefit of a direct correlation to the actual seismic behaviour of buildings and they are easy to handle also on huge stocks of buildings. Within this context, the paper illustrates a macroseismic vulnerability model for unreinforced masonry existing buildings that starts from the original proposal of Lagomarsino and Giovinazzi (Bull Earthquake Eng 4(4):445–463, 2006) and has further developed in recent years. The method may be classified as heuristic, in the sense that: (a) it is based on the expertise that is implicit in the European Macroseismic Scale (EMS98), with fuzzy assumptions on the binomial damage distribution; (b) it is calibrated on the observed damage in Italy, available in the database Da.D.O. developed by the Italian Department of Civil Protection (DPC). This approach guarantees a fairly well fitting with actual damage but, at the same time, ensures physically consistent results for both low and high values of the seismic intensity (for which observed data are incomplete or lacking). Moreover, the method provides a coherent distribution between the different damage levels. The valuable data in Da.D.O. allowed significant improvements of the method than its original version. The model has been recently applied in the context of ReLUIS project, funded by the DPC to support the development of Italian Risk Maps. To this aim, the vulnerability model has been applied for deriving fragility curves. This step requires to introduce a correlation law between the Macroseismic Intensity (adopted for the calibration of the model from a wide set of real damage data) and the Peak Ground Acceleration (at present, one of most used instrumental intensity measures); this conversion further increases the potential of the macroseismic method. As presented in the paper, the first applications of the model have produced plausible and consistent results at national scale, both in terms of damage scenarios and total risk (economic loss, consequences to people).

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Palaeoseismologic and geomorphic investigations along the middle portion of the Ovindoli-Pezza Fault (Central Italy)

Annals of Geophysics ◽

10.4401/ag-3998 ◽

1996 ◽

Vol 39 (3) ◽

Author(s):

G. D' Addezio ◽

D. Pantosti ◽

P. M. De Martini

Keyword(s):

Central Italy ◽

Slip Rate ◽

Vertical Movement ◽

The Other ◽

Recurrence Time ◽

Middle Portion ◽

Seismic Behaviour ◽

Horizontal Movement ◽

Seismogenic Faults ◽

Using Data

his paper presents the results of a detailed investigation performed along the central part of the Ovindoli- Pezza Fault with the aim of improving our understanding of the seismic behaviour of this fault within Central Italy seismogenesis. Results of the trenching investigations we performed across the central part of the fault confirm and strengthen the results obtained at other sites located in the northern part. There is clear evidence that the two most recent surface faulting events occurred within the same interval of time at the different trench sites and thus, at least during these two events, the fault was activated for its entire length. The most recent surface faulting event occurred between 860 and 1300 A.D. Geomorphic and microtopographic investigations indicate that although the trace of the fault shows an important bend, the kinematics of the fault seem to be prevalently normal, consistent with the other seismogenic faults that accommodate the NE-SW extension in this part of the Apennines. The maximum horizontal movement derived using geomorphic methods along the central part of the Ovindoli-Pezza Fault did not exceed 30% of the vertical movement. Slip rate and average recurrence interval were obtained using data both from trenching and Late Pleistocene-Holocene geomorphology. Resulting slip rate ranges between 0.7 and 1.2 mm/year whereas the average recurrence time varies between 1000 and 3000 years.

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3D Linked Subduction, Dynamic Rupture, Tsunami, and Inundation Modeling: Dynamic Effects of Supershear and Tsunami Earthquakes, Hypocenter Location, and Shallow Fault Slip

Frontiers in Earth Science ◽

10.3389/feart.2021.626844 ◽

2021 ◽

Vol 9 ◽

Author(s):

Sara Aniko Wirp ◽

Alice-Agnes Gabriel ◽

Maximilian Schmeller ◽

Elizabeth H. Madden ◽

Iris van Zelst ◽

...

Keyword(s):

Subduction Zones ◽

Large Scale ◽

Slip Rate ◽

Building Blocks ◽

Fault Slip ◽

Tsunami Source ◽

Dynamic Rupture ◽

Earthquake Scenarios ◽

Sloping Beach ◽

Tsunami Amplitude

Physics-based dynamic rupture models capture the variability of earthquake slip in space and time and can account for the structural complexity inherent to subduction zones. Here we link tsunami generation, propagation, and coastal inundation with 3D earthquake dynamic rupture (DR) models initialized using a 2D seismo-thermo-mechanical geodynamic (SC) model simulating both subduction dynamics and seismic cycles. We analyze a total of 15 subduction-initialized 3D dynamic rupture-tsunami scenarios in which the tsunami source arises from the time-dependent co-seismic seafloor displacements with flat bathymetry and inundation on a linearly sloping beach. We first vary the location of the hypocenter to generate 12 distinct unilateral and bilateral propagating earthquake scenarios. Large-scale fault topography leads to localized up- or downdip propagating supershear rupture depending on hypocentral depth. Albeit dynamic earthquakes differ (rupture speed, peak slip-rate, fault slip, bimaterial effects), the effects of hypocentral depth (25–40 km) on tsunami dynamics are negligible. Lateral hypocenter variations lead to small effects such as delayed wave arrival of up to 100 s and differences in tsunami amplitude of up to 0.4 m at the coast. We next analyse inundation on a coastline with complex topo-bathymetry which increases tsunami wave amplitudes up to ≈1.5 m compared to a linearly sloping beach. Motivated by structural heterogeneity in subduction zones, we analyse a scenario with increased Poisson's ratio of ν = 0.3 which results in close to double the amount of shallow fault slip, ≈1.5 m higher vertical seafloor displacement, and a difference of up to ≈1.5 m in coastal tsunami amplitudes. Lastly, we model a dynamic rupture “tsunami earthquake” with low rupture velocity and low peak slip rates but twice as high tsunami potential energy. We triple fracture energy which again doubles the amount of shallow fault slip, but also causes a 2 m higher vertical seafloor uplift and the highest coastal tsunami amplitude (≈7.5 m) and inundation area compared to all other scenarios. Our mechanically consistent analysis for a generic megathrust setting can provide building blocks toward using physics-based dynamic rupture modeling in Probabilistic Tsunami Hazard Analysis.

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The Río Grío–Pancrudo Fault Zone (central Iberian Chain, Spain): recent extensional activity revealed by drainage reversal

Geological Magazine ◽

10.1017/s0016756821000790 ◽

2021 ◽

pp. 1-16

Author(s):

Alba Peiro ◽

José L. Simón

Keyword(s):

Fault Zone ◽

Large Scale ◽

Hanging Wall ◽

Slip Rate ◽

Vertical Displacement ◽

Geological Mapping ◽

Fault Segment ◽

Iberian Chain ◽

Basin Margin ◽

Erosion Surface

Abstract The NNW–SSE-trending extensional Río Grío–Pancrudo Fault Zone is a large-scale structure that obliquely cuts the Neogene NW–SE Calatayud Basin. Its negative inversion during the Neogene–Quaternary extension gave rise to structural and geomorphological rearrangement of the basin margin. Geological mapping has allowed two right-relayed fault segments to be distinguished, whose recent extensional activity has been mainly characterized using a deformed planation surface (Fundamental Erosion Surface (FES) 3; 3.5 Ma) as a geomorphic marker. Normal slip along the Río Grío–Lanzuela Fault Segment has induced hanging-wall tilting, subsequent drainage reversal at the Güeimil valley after the Pliocene–Pleistocene transition, as well as morphological scarps and surficial ruptures in Pleistocene materials. In this sector, an offset of FES3 indicates a total throw of c. 240 m, resulting in a slip rate of 0.07 mm a–1, while retrodeformation of hanging-wall tilting affecting a younger piedmont surface allows the calculation of a minimum throw in the range of 140–220 m after the Pliocene–Pleistocene transition, with a minimum slip rate of 0.07–0.11 mm a–1. For the late Pleistocene period, vertical displacement of c. 20 m of a sedimentary level dated to 66.6 ± 6.5 ka yields a slip rate approaching 0.30–0.36 mm a–1. At the Cucalón–Pancrudo Fault Segment, the offset of FES3 allows the calculation of a maximum vertical slip of 300 m for the last 3.5 Ma, and hence a net slip rate close to 0.09 mm a–1. Totalling c. 88 km in length, the Río Grío–Pancrudo Fault Zone could be the largest recent macrostructure in the Iberian Chain, probably active, with the corresponding undeniable seismogenic potential.

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Interseismic Deformation in the Gulf of Aqaba Inferred from GPS Measurements

10.5194/egusphere-egu2020-13045 ◽

2020 ◽

Author(s):

Nicolas Castro-Perdomo ◽

Renier Viltres ◽

Frédéric Masson ◽

Patrice Ulrich ◽

Jean-Daniel Bernard ◽

...

Keyword(s):

Large Scale ◽

Slip Rate ◽

Fault System ◽

Arabian Plate ◽

Gulf Of Aqaba ◽

Postseismic Deformation ◽

Euler Pole ◽

Finite Fault ◽

Starting Point ◽

Interseismic Deformation

The Dead Sea Transform fault forms the boundary between the Arabian plate and the Sinai-Levant subplate. Several aspects of this fault system have been extensively studied during the last century. However, the present-day kinematics and deformation along its southern end in the Gulf of Aqaba remain poorly understood. Here we present a crustal motion velocity field based on three GPS surveys conducted between 2015 and 2019 at 30 campaign sites, complemented by 12 permanent stations operating near the gulf. We constrained a pole of rotation for the Sinai-Levant subplate based on five selected stations on the Sinai Peninsula. This Euler pole predicts a left-lateral slip rate of ~4.5 mm/yr on the fault system in the gulf, consistent with earlier findings. We find that standard models of interseismic deformation, such as back-slip and screw dislocation models do not provide a reasonable constraint on fault locking depths due to limited near-fault measurements. Despite this, our results reveal a small (~1 mm/yr) but systematic left-lateral residual motion across the gulf that cannot be resolved by elastic models of strain accumulation. We further find that the orientation of these residuals agrees with modelled postseismic transient motions caused by the 1995 MW 7.2 Nuweiba earthquake in the NE and SW quadrants relative to the gulf trend. Combined, these observations suggest that postseismic deformation caused by the Nuweiba earthquake may still be ongoing. We anticipate our findings to be a starting point for future geodetic studies in the northern Red Sea region where large-scale infrastructure mega-projects, such as the NEOM city and the King Salman bridge across the gulf are being developed. Future studies would benefit from incorporating additional GPS stations on the Sinai side of the gulf, refined finite-fault models, seafloor geodetic measurements and better information about past earthquakes.

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Joint inversion of InSAR and GPS for fine slip rate and locking degree distribution along the Haiyuan fault zone

10.5194/egusphere-egu2020-2539 ◽

2020 ◽

Author(s):

Chunyan Qu ◽

Xin Qiao

Keyword(s):

Fault Zone ◽

Deformation Rate ◽

Large Scale ◽

Joint Inversion ◽

Slip Rate ◽

High Density ◽

Fault System ◽

Tibet Plateau ◽

Dislocation Model ◽

Fault Deformation

The left-lateral strike-slip Haiyuan fault system is a major boundary fault zone on the northeast margin of the Qinghai -Tibet Plateau&#65292;separating active Tibet block and stable Alaxan & rdos blocks, and accommodating the eastward motion of Tibet Plateau. It consists of several sections, including Lenglongling segment (LLL), the Jinqianghe segment (JQH), the Maomaoshan segment (MMS), the Laohushan segment (LHS) and the rupture of the Haiyuan earthquake in 1920 from the west to the east. In 1920, a M8.5 Haiyuan earthquake occurred in the eastern segment of the fault zone, resulting in a surface rupture zone of about 240 km, with a maximum left-lateral coseismic displacement of 10 m. In the past 100 years after the earthquake, Haiyan fault is in a state of calm, no destructive earthquake of M 6.0 or above occurred. It is worth studying that how the fault activity and seismic hazard of each section of Haiyuan fault zone are at present.We use geodetic data (High density InSAR and wide scale GPS) to study the present slip rate and locking degree of Haiyuan fault zone. we first use the Envisat/ASAR long-strip data of five tracks and the PSInSAR time series processing technology based on high coherence point target to obtain the average deformation rate field of the fault system during 2003~2010, and transform the deformation rate from line-of-sight (LOS) direction to the parallel fault direction. Then,we use two-dimensional screw dislocation model to fit the cross-fault deformation rate profiles, and obtain the fault kinematic parameters such as the fault slip rate and the locking depth. At the same time,&#160;we adopt the three-dimensional block model to invert the distribution characteristics of fault locking degree and slip rate deficit along the Haiyuan fault zone. We compare the difference of inversion results of different data individually and jointly, including large-scale sparse GPS data, high-density InSAR data and the combination of them. Finally we get the continuous strain accumulation state of the fault zone. The results show that from west to east, the slip rate decreases gradually, while the locking depth changes along the fault. The Laohushan section shows shallow surface creep. The analysis of the high-density cross-fault deformation rate profile of the Laohushan segment indicates that the creep length is about 19 km. Other segments in a locked state. But in the middle of the 1920 erathquake fracture section, the locking degree is weaker and shallower than other segments. These results are helpful to understand the present activity and assess regional seismic risk of Haiyuan fault zone.

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