Hybrid Simulation of Near-Fault Ground Motion for a Potential Mw 7 Earthquake in Lebanon

2021 ◽  
Vol 111 (5) ◽  
pp. 2441-2462 ◽  
Author(s):  
Rosemary Fayjaloun ◽  
Mayssa Dabaghi ◽  
Cecile Cornou ◽  
Mathieu Causse ◽  
Yang Lu ◽  
...  
Keyword(s):  
Ground Motion ◽  
Velocity Structure ◽  
Ground Motions ◽  
Seismic Energy ◽  
Velocity Model ◽  
Historical Seismicity ◽  
Stochastic Simulations ◽  
Hybrid Technique ◽  
Rupture Directivity ◽  
Near Fault

ABSTRACT Lebanon is a densely populated country crossed by major faults. Historical seismicity shows the potential of earthquakes with magnitudes >7, but large earthquakes have never been instrumentally recorded in Lebanon. Here, we propose a method to simulate near-fault broadband ground motions for a potential Mw 7 earthquake on the Yammouneh fault (YF)—the largest branch of the Dead Sea Transform fault that bisects Lebanon from north to south. First, we performed the first 3D tomography study of Lebanon using ambient noise correlation, which showed that Lebanon could be approximated by a 1D velocity structure for low-frequency (LF) ground-motion simulation purposes. Second, we generated suites of kinematic rupture models on the YF, accounting for heterogeneity of the rupture process, and uncertainty of the rupture velocity and hypocenter location. The radiated seismic energy was next propagated in the inferred 1D velocity model to obtain suites of LF ground motions (<1 Hz) at four hypothetical near-fault seismic stations. These LF simulations included the main features of near-fault ground motions, such as the impulsive character of ground velocity due to the rupture directivity or fling-step effects (so-called pulse-like ground motions). Third, to obtain broadband ground motions (up to 10 Hz), we proposed a hybrid technique that combined the simulated LF ground motions with high-frequency (HF) stochastic simulations, which were empirically calibrated using a worldwide database of near-fault recordings. Contrary to other hybrid approaches, in which the LF and HF motions are generally computed independently, the characteristics of stochastic HF ground motions were conditioned on those of LF ground motions (namely on the characteristics of the velocity pulse, if it existed, or on the absence of a pulse). The simulated peak ground accelerations were in agreement with the ones reported in the Next Generation Attenuation-West2 (NGA-West2) database for similar magnitude and distances and with three NGA-West2 ground-motion prediction equations.

Deterministic 3D Ground-Motion Simulations (0–5 Hz) and Surface Topography Effects of the 30 October 2016 Mw 6.5 Norcia, Italy, Earthquake

2021 ◽  
Author(s):  
Arben Pitarka ◽  
Aybige Akinci ◽  
Pasquale De Gori ◽  
Mauro Buttinelli
Keyword(s):  
Surface Topography ◽  
Ground Motion ◽  
Seismic Station ◽  
Ground Motions ◽  
Peak Ground Velocity ◽  
Earth Model ◽  
Rupture Directivity ◽  
Epicentral Area ◽  
Near Fault ◽  
Local Topography

ABSTRACT The Mw 6.5 Norcia, Italy, earthquake occurred on 30 October 2016 and caused extensive damage to buildings in the epicentral area. The earthquake was recorded by a network of strong-motion stations, including 14 stations located within a 5 km distance from the two causative faults. We used a numerical approach for generating seismic waves from two hybrid deterministic and stochastic kinematic fault rupture models propagating through a 3D Earth model derived from seismic tomography and local geology. The broadband simulations were performed in the 0–5 Hz frequency range using a physics-based deterministic approach modeling the earthquake rupture and elastic wave propagation. We used SW4, a finite-difference code that uses a conforming curvilinear mesh, designed to model surface topography with high numerical accuracy. The simulations reproduce the amplitude and duration of observed near-fault ground motions. Our results also suggest that due to the local fault-slip pattern and upward rupture directivity, the spatial pattern of the horizontal near-fault ground motion generated during the earthquake was complex and characterized by several local minima and maxima. Some of these local ground-motion maxima in the near-fault region were not observed because of the sparse station coverage. The simulated peak ground velocity (PGV) is higher than both the recorded PGV and predicted PGV based on empirical models for several areas located above the fault planes. Ground motions calculated with and without surface topography indicate that, on average, the local topography amplifies the ground-motion velocity by 30%. There is correlation between the PGV and local topography, with the PGV being higher at hilltops. In contrast, spatial variations of simulated PGA do not correlate with the surface topography. Simulated ground motions are important for seismic hazard and engineering assessments for areas that lack seismic station coverage and historical recordings from large damaging earthquakes.

Three-dimensional simulation of the near-fault ground motion for the 1995 Hyogo-Ken Nanbu (Kobe), Japan, earthquake

1998 ◽  
Vol 88 (2) ◽  
pp. 428-440 ◽  
Author(s):  
Arben Pitarka ◽  
Kojiro Irikura ◽  
Tomotaka Iwata ◽  
Haruko Sekiguchi
Keyword(s):  
Ground Motion ◽  
Velocity Structure ◽  
Ground Motions ◽  
Three Dimensional ◽  
High Amplitude ◽  
Near Fault ◽  
Basin Edge ◽  
Dimensional Simulation ◽  
Near Fault Ground Motion ◽  
East West

Abstract The 17 January 1995 Hyogo-ken Nanbu earthquake is a typical example showing that the ground motions along basin-edge faults can be very destructive. In this study, we simulate the near-fault ground motion from this earthquake based on a kinematic fault model and a simplified 3D velocity structure of the Kobe area. The kinematic earthquake rupture and the wave propagation are modeled using a 3D finite-difference method (FDM). Our simulation identifies the basin-edge effect as an important factor that influenced the ground-motion amplification pattern in the Kobe area. We found that the coupling of the source directivity and basin-edge effects causes impulsive ground motions with extremely high amplitude at periods greater than 1 sec and in a narrow zone offset less than 1 km from the basin edge. The combination of these effects acted to create a fairly continuous band of amplification that extends about 30 km in an elongated zone parallel to the basin-edge boundary. In some areas, localized site effects might have been as important as the abovementioned effects, but they cannot explain the continuity of the extended east-west zone of damage.

scholarly journals Simulation of non-stationary stochastic ground motions based on recent Italian earthquakes

2021 ◽  
Author(s):  
Fabio Sabetta ◽  
Antonio Pugliese ◽  
Gabriele Fiorentino ◽  
Giovanni Lanzano ◽  
Lucia Luzi
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Strong Motion ◽  
Stochastic Simulations ◽  
Model Parameters ◽  
Motion Model ◽  
Arias Intensity ◽  
Time Frequency ◽  
Ground Motion Model ◽  
Ground Motion Records

AbstractThis work presents an up-to-date model for the simulation of non-stationary ground motions, including several novelties compared to the original study of Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996). The selection of the input motion in the framework of earthquake engineering has become progressively more important with the growing use of nonlinear dynamic analyses. Regardless of the increasing availability of large strong motion databases, ground motion records are not always available for a given earthquake scenario and site condition, requiring the adoption of simulated time series. Among the different techniques for the generation of ground motion records, we focused on the methods based on stochastic simulations, considering the time- frequency decomposition of the seismic ground motion. We updated the non-stationary stochastic model initially developed in Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996) and later modified by Pousse et al. (Bull Seism Soc Am 96:2103–2117, 2006) and Laurendeau et al. (Nonstationary stochastic simulation of strong ground-motion time histories: application to the Japanese database. 15 WCEE Lisbon, 2012). The model is based on the S-transform that implicitly considers both the amplitude and frequency modulation. The four model parameters required for the simulation are: Arias intensity, significant duration, central frequency, and frequency bandwidth. They were obtained from an empirical ground motion model calibrated using the accelerometric records included in the updated Italian strong-motion database ITACA. The simulated accelerograms show a good match with the ground motion model prediction of several amplitude and frequency measures, such as Arias intensity, peak acceleration, peak velocity, Fourier spectra, and response spectra.

Numerical Modeling of Near Fault Seismic Ground Motion for Denali Fault

2021 ◽  
Vol 12 (2) ◽  
pp. 0-0
Keyword(s):  
Ground Motion ◽  
Peak Ground Acceleration ◽  
Numerical Study ◽  
Ground Motions ◽  
Numerical Results ◽  
Fault Rupture ◽  
Ground Acceleration ◽  
Denali Fault ◽  
Near Fault ◽  
Good Agreement

An effective earthquake (Mw 7.9) struck Alaska on 3 November, 2002. This earthquake ruptured 340 km along Susitna Glacier, Denali and Totschunda faults in central Alaska. The peak ground acceleration (PGA) was recorded about 0.32 g at station PS10, which was located 3 km from the fault rupture. The PGA would have recorded a high value, if more instruments had been installed in the region. A numerical study has been conducted to find out the possible ground motion record that could occur at maximum horizontal slip during the Denali earthquake. The current study overcomes the limitation of number of elements to model the Denali fault. These numerical results are compared with observed ground motions. It is observed that the ground motions obtained through numerical analysis are in good agreement with observed ground motions. From numerical results, it is observed that the possible expected PGA is 0.62 g at maximum horizontal slip of Denali fault.

Evaluation of Earthquake Response Spectra Directionality Using Stochastic Simulations

2021 ◽  
Author(s):  
Alan Poulos ◽  
Eduardo Miranda ◽  
Jack W. Baker
Keyword(s):  
Stochastic Process ◽  
Ground Motion ◽  
Ground Motions ◽  
Gaussian White Noise ◽  
Response Spectra ◽  
Orientation Dependence ◽  
Stochastic Simulations ◽  
Earthquake Ground Motion ◽  
Significant Duration ◽  
Simulated Ground Motions

ABSTRACT For earthquake-resistant design purposes, ground-motion intensity is usually characterized using response spectra. The amplitude of response spectral ordinates of horizontal components varies significantly with changes in orientation. This change in intensity with orientation is commonly known as ground-motion directionality. Although this directionality has been attributed to several factors, such as topographic irregularities, near-fault effects, and local geologic heterogeneities, the mechanism behind this phenomenon is still not well understood. This work studies the directionality characteristics of earthquake ground-motion intensity using synthetic ground motions and compares their directionality to that of recorded ground motions. The two principal components of horizontal acceleration are sampled independently using a stochastic model based on finite-duration time-modulated filtered Gaussian white-noise processes. By using the same stochastic process to sample both horizontal components of motion, the variance of horizontal ground acceleration has negligible orientation dependence. However, these simulations’ response spectral ordinates present directionality levels comparable to those found in real ground motions. It is shown that the directionality of the simulated ground motions changes for each realization of the stochastic process and is a consequence of the duration being finite. Simulated ground motions also present similar directionality trends to recorded earthquake ground motions, such as the increase of average directionality with increasing period of vibration and decrease with increasing significant duration. These results suggest that most of the orientation dependence of horizontal response spectra is primarily explained by the finite significant duration of earthquake ground motion causing inherent randomness in response spectra, rather than by some physical mechanism causing polarization of shaking.

scholarly journals Analysis of the Seismic Demand of High-Performance Buckling-Restrained Braces under a Strong Earthquake and Its Aftershocks

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Luqi Xie ◽  
Jing Wu ◽  
Qing Huang ◽  
Chao Tong
Keyword(s):  
Plastic Deformation ◽  
Ground Motion ◽  
Strong Earthquake ◽  
High Performance ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Threshold Value ◽  
Seismic Demand ◽  
Near Fault ◽  
Probabilistic Seismic Demand

The analysis of the ductility and cumulative plastic deformation (CPD) demand of a high-performance buckling-restrained brace (HPBRB) under a strong earthquake and its aftershocks is conducted in this paper. A combination of three continuous excitations with the same ground motion is used to simulate the affection of a strong earthquake and its aftershocks. A six-story HPBRB frame (HPBRBF) is taken as an example to conduct the incremental dynamic analysis (IDA). The seismic responses of the HPBRBF under one, two, and three constant continuous ground motions are compared. The IDA result indicates that the ductility and CPD demand of the BRBs under the three constant continuous ground motions are significantly larger than that excited by only one. Probabilistic seismic demand analysis (PSDA) is performed using seven near-fault ground motions and seven far-fault ground motions to consider the indeterminacy of ground motion. The probabilistic seismic demand curves (PSDCs) for the ductility and CPD demand for the HPBRB under the strong earthquake and its aftershocks are obtained in combining the probabilistic seismic hazard analysis. The results indicate that the AISC threshold value of the CPD with 200 is excessively low for a HPBRBF which suffers the continuous strong aftershocks with near-fault excitations, and a stricter threshold value should be suggested to ensure the ductility and plastic deformation capacity demand of the HPBRB.

Conditional Ground-Motion Model for Damaging Characteristics of Near-Fault Ground Motions Based on Instantaneous Power

2020 ◽  
Vol 110 (6) ◽  
pp. 2828-2842
Author(s):  
Esra Zengin ◽  
Norman Abrahamson
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Accurate Estimation ◽  
Spectral Acceleration ◽  
Motion Model ◽  
Velocity Pulse ◽  
Near Fault ◽  
Instantaneous Power ◽  
Ground Motion Model ◽  
Short Time

ABSTRACT The velocity pulse in near-fault ground motions has been used as a key characteristic of damaging ground motions. Characterization of the velocity pulse involves three parameters: presence of the pulse, period of the pulse, and amplitude of the pulse. The basic concept behind the velocity pulse is that a large amount of seismic energy is packed into a short time, leading to larger demands on the structure. An intensity measure for near-fault ground motions, which is a direct measure of the amount of energy arriving in short time, called instantaneous power (IP (T1)), is defined as the maximum power of the bandpass-filtered velocity time series measured over a time interval of 0.5T1, in which T1 is the fundamental period of the structure. The records are bandpass filtered in the period band (0.2T1−3T1) to remove the frequencies that are not expected to excite the structure. Zengin and Abrahamson (2020) showed that the drift is better correlated with the IP (T1) than with the velocity pulse parameters for records scaled to the same spectral acceleration at T1. A conditional ground-motion model (GMM) for the IP is developed based on the 5%-damped spectral acceleration at T1, the earthquake magnitude, and the rupture distance. This conditional GMM can be used for record selection for near-fault ground motions that captures the key features of velocity pulses and can lead to a better representation of the median and variability of the maximum interstory drift. The conditional GMM can also be used in a vector hazard analysis for spectral acceleration (T1) and IP (T1) that can be used for more accurate estimation of drift hazard and seismic risk.

Performance of Seismic-Isolated Bridges in Relation to Near-Fault Ground-Motion and Isolator Characteristics

2006 ◽  
Vol 22 (4) ◽  
pp. 887-907 ◽  
Author(s):  
Murat Dicleli
Keyword(s):  
Ground Motion ◽  
Seismic Isolation ◽  
Elastic Stiffness ◽  
Rupture Directivity ◽  
Directivity Effect ◽  
Critical Design ◽  
Near Fault ◽  
Near Fault Ground Motion ◽  
Isolated Bridges ◽  
Forward Rupture Directivity

This paper investigates the performance of seismic-isolated bridges (SIBs) subjected to near-fault (NF) earthquakes with forward rupture directivity effect (FRDE) in relation to the isolator, substructure, and NF earthquake properties, and examines some critical design clauses in AASHTO's Guide Specifications for Seismic Isolation Design. It is found that the SIB response is a function of the number of velocity pulses, magnitude of the NF ground motion, and distance from the fault. Particularly, a reasonable estimation of the expected magnitude of the NF ground motion according to the characteristics of the bridge site is crucial for a correct design of the SIB. It is also found that the characteristic strength and post-elastic stiffness of the isolator may be chosen based on the characteristics of the NF earthquake. Furthermore, some of the AASHTO clauses are found to be not applicable to SIBs subjected to NF ground motions with FRDE.

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