scholarly journals A Bayesian approach to determine the average shape of the slip-rate function and the rupture velocity using near-field phases: the 2003 Mw6.6 Bam earthquake example

2014 ◽  
Vol 199 (1) ◽  
pp. 604-613
Author(s):  
A. Ozgun Konca ◽  
Michel Bouchon
Keyword(s):  
Bayesian Approach ◽  
Near Field ◽  
Slip Rate ◽  
Rate Function ◽  
Rupture Velocity ◽  
Bam Earthquake ◽  
Average Shape

Multicycle Simulation of Strike-Slip Earthquake Rupture for Use in Near-Source Ground-Motion Simulations

2021 ◽  
Author(s):  
Percy Galvez ◽  
Anatoly Petukhin ◽  
Paul Somerville ◽  
Jean-Paul Ampuero ◽  
Ken Miyakoshi ◽  
...  
Keyword(s):  
Ground Motion ◽  
Stress Drop ◽  
Slip Rate ◽  
Rupture Process ◽  
Earthquake Rupture ◽  
Rupture Velocity ◽  
Source Inversion ◽  
Dynamic Rupture ◽  
Wide Range ◽  
Source Scaling

ABSTRACT Realistic dynamic rupture modeling validated by observed earthquakes is necessary for estimating parameters that are poorly resolved by seismic source inversion, such as stress drop, rupture velocity, and slip rate function. Source inversions using forward dynamic modeling are increasingly used to obtain earthquake rupture models. In this study, to generate a large number of physically self-consistent rupture models, rupture process of which is consistent with the spatiotemporal heterogeneity of stress produced by previous earthquakes on the same fault, we use multicycle simulations under the rate and state (RS) friction law. We adopt a one-way coupling from multicycle simulations to dynamic rupture simulations; the quasidynamic solver QDYN is used to nucleate the seismic events and the spectral element dynamic solver SPECFEM3D to resolve their rupture process. To simulate realistic seismicity, with a wide range of magnitudes and irregular recurrence, several realizations of 2D-correlated heterogeneous random distributions of characteristic weakening distance (Dc) in RS friction are tested. Other important parameters are the normal stress, which controls the stress drop and rupture velocity during an earthquake, and the maximum value of Dc, which controls rupture velocity but not stress drop. We perform a parametric study on a vertical planar fault and generate a set of a hundred spontaneous rupture models in a wide magnitude range (Mw 5.5–7.4). We validate the rupture models by comparison of source scaling, ground motion (GM), and surface slip properties to observations. We compare the source-scaling relations between rupture area, average slip, and seismic moment of the modeled events with empirical ones derived from source inversions. Near-fault GMs are computed from the source models. Their peak ground velocities and peak ground accelerations agree well with the ground-motion prediction equation values. We also obtain good agreement of the surface fault displacements with observed values.

scholarly journals Development of an inversion method to extract information on fault geometry from teleseismic data

2019 ◽  
Vol 220 (2) ◽  
pp. 1055-1065 ◽  
Author(s):  
Kousuke Shimizu ◽  
Yuji Yagi ◽  
Ryo Okuwaki ◽  
Yukitoshi Fukahata
Keyword(s):  
Fault Plane ◽  
Slip Rate ◽  
Rate Function ◽  
Fault Slip ◽  
Body Waves ◽  
Fault System ◽  
Inversion Method ◽  
Fault Geometry ◽  
Finite Fault ◽  
Extract Information

SUMMARY Teleseismic waveforms contain information on fault slip evolution during an earthquake, as well as on the fault geometry. A linear finite-fault inversion method is a tool for solving the slip-rate function distribution under an assumption of fault geometry as a single or multiple-fault-plane model. An inappropriate assumption of fault geometry would tend to distort the solution due to Green’s function modelling errors. We developed a new inversion method to extract information on fault geometry along with the slip-rate function from observed teleseismic waveforms. In this method, as in most previous studies, we assumed a flat fault plane, but we allowed arbitrary directions of slip not necessarily parallel to the assumed fault plane. More precisely, the method represents fault slip on the assumed fault by the superposition of five basis components of potency-density tensor, which can express arbitrary fault slip that occurs underground. We tested the developed method by applying it to real teleseismic P waveforms of the MW 7.7 2013 Balochistan, Pakistan, earthquake, which is thought to have occurred along a curved fault system. The obtained spatiotemporal distribution of potency-density tensors showed that the focal mechanism at each source knot was dominated by a strike-slip component with successive strike angle rotation from 205° to 240° as the rupture propagated unilaterally towards the south-west from the epicentre. This result is consistent with Earth’s surface deformation observed in optical satellite images. The success of the developed method is attributable to the fact that teleseismic body waves are not very sensitive to the spatial location of fault slip, whereas they are very sensitive to the direction of fault slip. The method may be a powerful tool to extract information on fault geometry along with the slip-rate function without requiring detailed assumptions about fault geometry.

scholarly journals A combinatorial approach to determine earthquake magnitude distributions on a variable slip-rate fault

2019 ◽  
Vol 219 (2) ◽  
pp. 734-752 ◽  
Author(s):  
Eric L Geist ◽  
Tom Parsons
Keyword(s):  
Spatial Distribution ◽  
Integer Programming ◽  
Slip Rate ◽  
Rate Function ◽  
Programming Method ◽  
Sequential Algorithm ◽  
Rate Variation ◽  
Finite Sample ◽  
Decision Vector ◽  
Lower Magnitude

SUMMARY Combinatorial methods are used to determine the spatial distribution of earthquake magnitudes on a fault whose slip rate varies along strike. Input to the problem is a finite sample of earthquake magnitudes that span 5 kyr drawn from a truncated Pareto distribution. The primary constraints to the problem are maximum and minimum values around the target slip-rate function indicating where feasible solutions can occur. Two methods are used to determine the spatial distribution of earthquakes: integer programming and the greedy-sequential algorithm. For the integer-programming method, the binary decision vector includes all possible locations along the fault where each earthquake can occur. Once a set of solutions that satisfy the constraints is found, the cumulative slip misfit on the fault is globally minimized relative to the target slip-rate function. The greedy algorithm sequentially places earthquakes to locally optimize slip accumulation. As a case study, we calculate how earthquakes are distributed along the megathrust of the Nankai subduction zone, in which the slip rate varies significantly along strike. For both methods, the spatial distribution of magnitudes depends on slip rate, except for the largest magnitude earthquakes that span multiple sections of the fault. The greedy-sequential algorithm, previously applied to this fault (Parsons et al., 2012), tends to produce smoother spatial distributions and fewer lower magnitude earthquakes in the low slip-rate section of the fault compared to the integer-programming method. Differences in results from the two methods relate to how much emphasis is placed on minimizing the misfit to the target slip rate (integer programming) compared to finding a solution within the slip-rate constraints (greedy sequential). Specifics of the spatial distribution of magnitudes also depend on the shape of the target slip-rate function: that is, stepped at the section boundaries versus a smooth function. This study isolates the effects of slip-rate variation along a single fault in determining the spatial distribution of earthquake magnitudes, helping to better interpret results from more complex, interconnected fault systems.

Source Characteristics of the 2017 Ms 6.6 (Mw 6.3) Jinghe Earthquake in the Northeastern Tien Shan

2020 ◽  
Vol 91 (2A) ◽  
pp. 745-757
Author(s):  
Xu Zhang ◽  
Li-Sheng Xu ◽  
Jun Luo ◽  
Wanpeng Feng ◽  
Hai-Lin Du ◽  
...  
Keyword(s):  
Energy Release ◽  
Joint Inversion ◽  
Near Field ◽  
Tien Shan ◽  
Rupture Velocity ◽  
The West ◽  
Waveform Data ◽  
Source Characteristics ◽  
Seismic Waveform ◽  
Finite Fault

Abstract On 8 August 2017, an Ms 6.6 earthquake occurred in the northeastern Tien Shan orogenic belt. To reveal the source characteristics of this earthquake completely, the teleseismic and near-field seismic waveform data were collected as well as the coseismic Interferometric Synthetic Aperture Radar displacement data, and the methods of the backprojection and the finite-fault joint inversion were adopted. The backprojection of the teleseismic recordings indicates a unilateral rupture propagating 15 km westward. Two stages of the rupture were recognized from the backprojection results: in the first ∼5  s, the rupture took place near the hypocenter, with an accelerating energy release but a small rupture velocity; then the rupture extended to the west, with a decelerating energy release but a relatively fast rupture velocity. The joint inversion of the multiple datasets shows a major slip asperity of about 24  km × 18  km. The asperity extended mainly to the west, with a duration of approximately 10 s. The average rupture velocity over the asperity was estimated to be approximately 2.0  km/s, which is close to that 1.9  km/s estimated by the backprojection. It is interesting that the high-frequency sources were aligned almost on the margin of the slip asperity. Moreover, the occurrence of the earthquake sequence is found to relate with the low-VP/VS zone, implying a tectonic property, which controls the nucleation and rupture of earthquakes.

scholarly journals The Effect of Alternative Seismotectonic Models on PSHA Results – a Sensitivity Study for the Case of Israel

2017 ◽  
Author(s):  
Matan Avital ◽  
Michael Davis ◽  
Ory Dor ◽  
Ronnie Kamai
Keyword(s):  
Epistemic Uncertainty ◽  
Near Field ◽  
Uncertainty Propagation ◽  
Slip Rate ◽  
Parametric Uncertainty ◽  
Sensitivity Study ◽  
Prediction Equation ◽  
Fault System ◽  
Model Parameters ◽  
Alternative Source

Abstract. We present a full PSHA sensitivity analysis for two sites in southern Israel – one in the near-field of a major fault system and one farther away. The PSHA analysis is conducted for alternative source representations, using alternative model parameters for the main seismic sources, such as slip-rate and Mmax, among others. The analysis also considers the effect of the Ground-Motion Prediction Equation (GMPE) on the hazard results. In this way, the two types of epistemic uncertainty – modelling uncertainty and parametric uncertainty are treated and addressed. We quantify the uncertainty propagation by testing its influence of the final calculated hazard, such that the controlling knowledge gaps are identified and can be treated in future studies. We find that current practice in Israel, as represented by the most current version of the building code grossly underestimates the hazard, due to a combination of factors, including source definitions as well as the GMPE used for analysis.

scholarly journals Rupture velocity inferred from near-field shear strain analysis

2014 ◽  
Vol 199 (3) ◽  
pp. 1709-1712 ◽  
Author(s):  
M. Causse ◽  
C. Cornou ◽  
J. Bécasse
Keyword(s):  
Shock Waves ◽  
Phase Velocity ◽  
Shear Strain ◽  
Fractured Rock ◽  
Near Field ◽  
Strain Analysis ◽  
Rupture Velocity ◽  
Fault Trace ◽  
A New Technique ◽  
Rupture Direction

Abstract We propose a new technique to determine the rupture velocity of large strike slip earthquakes. By means of simple numerical ground motion simulations, we show that when the rupture penetrates a shallow layer of sediment or fractured rock, shock waves propagate along the surface fault trace in the forward rupture direction. Such shock waves, which are insensitive to the complexity of slip over the fault plane, propagate at a phase velocity equal to the rupture speed. We show that those shock waves can be easily isolated in the frequency domain, and that phase velocity can then be simply obtained from shear strain.

scholarly journals The effect of alternative seismotectonic models on PSHA results – a sensitivity study for two sites in Israel

2018 ◽  
Vol 18 (2) ◽  
pp. 499-514 ◽  
Author(s):  
Matan Avital ◽  
Ronnie Kamai ◽  
Michael Davis ◽  
Ory Dor
Keyword(s):  
Epistemic Uncertainty ◽  
Hazard Analysis ◽  
Near Field ◽  
Slip Rate ◽  
Parametric Uncertainty ◽  
Sensitivity Study ◽  
Fault System ◽  
Model Parameters ◽  
Return Periods ◽  
Alternative Source

Abstract. We present a full probabilistic seismic hazard analysis (PSHA) sensitivity analysis for two sites in southern Israel – one in the near field of a major fault system and one farther away. The PSHA analysis is conducted for alternative source representations, using alternative model parameters for the main seismic sources, such as slip rate and Mmax, among others. The analysis also considers the effect of the ground motion prediction equation (GMPE) on the hazard results. In this way, the two types of epistemic uncertainty – modelling uncertainty and parametric uncertainty – are treated and addressed. We quantify the uncertainty propagation by testing its influence on the final calculated hazard, such that the controlling knowledge gaps are identified and can be treated in future studies. We find that current practice in Israel, as represented by the current version of the building code, grossly underestimates the hazard, by approximately 40 % in short return periods (e.g. 10 % in 50 years) and by as much as 150 % in long return periods (e.g. 10E−5). The analysis shows that this underestimation is most probably due to a combination of factors, including source definitions as well as the GMPE used for analysis.

scholarly journals Spatial–temporal properties of afterslip associated with the 2015 Mw 8.3 Illapel earthquake, Chile

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Yunfei Xiang ◽  
Jianping Yue ◽  
Zhongshan Jiang ◽  
Yin Xing
Keyword(s):  
Early Stage ◽  
Near Field ◽  
Temporal Distribution ◽  
Slip Rate ◽  
Fault Slip ◽  
Coseismic Slip ◽  
Temporal Properties ◽  
Time Period ◽  
Illapel Earthquake ◽  
Postseismic Slip

AbstractIn order to characterize the spatial–temporal properties of postseismic slip motions associated with the 2015 Illapel earthquake, the daily position time series of 13 GNSS sites situated at the near-field region are utilized. Firstly, a scheme of postseismic signal extraction and modeling is introduced, which can effectively extract the postseismic signal with consideration of background tectonic movement. Based on the extracted postseismic signal, the spatial–temporal distribution of afterslip is inverted under the layered medium model. Compared with coseismic slip distribution, the afterslip is extended to both deep and two sides, and two peak slip patches are formed on the north and south sides. The afterslip is mainly cumulated at the depth of 10–50 km, and the maximum slip reaches 1.46 m, which is situated at latitude of − 30.50°, longitude of − 71.78°, and depth of 18.94 m. Moreover, the postseismic slip during the time period of 0–30 days after this earthquake is the largest, and the maximum of fault slip and corresponding slip rate reaches 0.62 m and 20.6 mm/day. Whereas, the maximum of fault slip rate during the time period of 180–365 days is only around 1 mm/day. The spatial–temporal evolution of postseismic slip motions suggests that large postseismic slip mainly occurs in the early stage after this earthquake, and the fault tend to be stable as time goes on. Meanwhile, the Coulomb stress change demonstrate that the postseismic slip motions after the Illapel earthquake may be triggered by the stress increase in the deep region induced by coseismic rupture.

scholarly journals Spatial Variability of Near-field Ground Motions from Pseudo-Dynamic Rupture Simulations

2021 ◽  
Author(s):  
Jayalakshmi Sivasubramonian ◽  
Paul Martin Mai
Keyword(s):  
Ground Motion ◽  
Rise Time ◽  
Time Distribution ◽  
Velocity Structure ◽  
Ground Motions ◽  
Near Field ◽  
Source Parameters ◽  
Rupture Velocity ◽  
Earthquake Source Parameters ◽  
Ground Motion Variability

<p>We analyze the effect of earthquake source parameters on ground-motion variability based on near-field wavefield simulations for large earthquakes. We quantify residuals in simulated ground motion intensities with respect to observed records, the associated variabilities are then quantified with respect to source-to-site distance and azimuth. Additionally, we compute the variabilities due to complexities in rupture models by considering variations in hypocenter location and slip distribution that are implemented a new Pseudo-Dynamic (PD) source parameterization.</p><p>In this study, we consider two past events – the Mw 6.9 Iwate Miyagi Earthquake (2008), Japan, and the Mw 6.5 Imperial Valley Earthquake, California (1979). Assuming for each case a 1D velocity structure, we first generate ensembles of rupture models using the pseudo-dynamic approach of Guatteri et.al (2004), by assuming different hypocenter and asperities locations (Mai and Beroza, 2002, Mai et al., 2005; Thingbaijam and Mai, 2016). In order to efficiently include variations in high-frequency radiation, we adopt a PD parameterization for rupture velocity and rise time distribution in our rupture model generator. Overall, we generate a database of rupture models with 50 scenarios for each source parameterization. Synthetic near-field waveforms (0.1-2.5Hz) are computed out to Joyner-Boore distances Rjb ~ 150km using a discrete-wavenumber finite-element method (Olson et al., 1984). Our results show that ground-motion variability is most sensitive to hypocenter locations on the fault plane. We also find that locations of asperities do not alter waveforms significantly for a given hypocenter, rupture velocity and rise time distribution. We compare the scenario-event simulated ground motions with simulations that use the rupture models from the SRCMOD database (Mai and Thingbaijam, 2014), and find that the PD method is capable of reducing the ground motion variability at high frequencies. The PD models are calibrated by comparing the mean residuals with the residuals from SRCMOD models. We present the variability due to each source parameterization as a function of Joyner-Boore distance and azimuth at different natural period.</p>

scholarly journals Parameter interdependence of dynamic self-similar crack with distance-weakening friction

2020 ◽  
Vol 223 (3) ◽  
pp. 1584-1596
Author(s):  
Shiro Hirano ◽  
Hiromichi Itou
Keyword(s):  
Energy Release Rate ◽  
Fracture Energy ◽  
Energy Release ◽  
Crack Growth ◽  
Release Rate ◽  
Process Zone ◽  
Slip Rate ◽  
Zone Size ◽  
Rupture Velocity ◽  
Self Similar

SUMMARY In several analytical and numerical studies, the slip rate function and energy release rate for dynamic self-similar crack growth have been investigated, and the results obtained have contributed to a theoretical understanding and estimation of on-fault energetics. However, the relationships among physical parameters, including stress state, process zone size, rupture velocity, peak slip rate and energy release rate, are still unclear. Therefore, the aim of this study is to derive an analytical solution of the slip rate distribution of antiplane self-similar crack growth under distance-weakening friction that mimics slip-weakening friction. To satisfy the condition that the slip rate starts from zero at the rupture front, a trade-off relationship among rupture velocity, process zone size and breakdown stress-to-stress drop ratio is proposed. The peak slip rate, slip-weakening distance and fracture energy obtained using the proposed model provide a possible mechanism for the determination of the rupture velocity and the estimation of the fracture energy of the self-similar crack growth, based on the seismic observables.

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