Ground Motion Simulation Research Articles

A Physics-Based Seismic Risk Assessment of the Qujiang Fault: From Dynamic Rupture to Disaster Estimation

This study achieved the construction of earthquake disaster scenarios based on physics-based methods—from fault dynamic rupture to seismic wave propagation—and then population and economic loss estimations. The physics-based dynamic rupture and strong ground motion simulations can fully consider the three-dimensional complexity of physical parameters such as fault geometry, stress field, rock properties, and terrain. Quantitative analysis of multiple seismic disaster scenarios along the Qujiang Fault in western Yunnan Province in southwestern China based on different nucleation locations was achieved. The results indicate that the northwestern segment of the Qujiang Fault is expected to experience significantly higher levels of damage compared to the southeastern segment. Additionally, there are significant variations in human losses, even though the economic losses are similar across different scenarios. Dali Bai Autonomous Prefecture, Chuxiong Yi Autonomous Prefecture, Yuxi City, Honghe Hani and Yi Autonomous Prefecture, and Wenshan Zhuang and Miao Autonomous Prefecture were identified as at medium to high seismic risks, with Yuxi and Honghe being particularly vulnerable. Implementing targeted earthquake prevention measures in Yuxi and Honghe will significantly mitigate the potential risks posed by the Qujiang Fault. Notably, although the fault is within Yuxi, Honghe is likely to suffer the most severe damage. These findings emphasize the importance of considering rupture directivity and its influence on ground motion distribution when assessing seismic risk.

The 3D Physics-Based Broadband Ground-Motion Simulation, including Topography Effects Causing Damage to Structures, for the 2022 Mw 6.6 Menyuan, China, Earthquake

ABSTRACT On 8 January 2022, Menyuan County, China, was struck by an Mw 6.6 earthquake that caused surface rupture in the epicentral area and severe damage to an important railway bridge. The earthquake was recorded by only one strong-motion station, which presents a challenge for quantitatively estimating the extent of the ground-motion distribution caused by this event. In this study, the spectral element method (SPECFEM3D code), which solves the elastodynamic equations and can capture the full physics of seismic-wave propagation, is employed for broadband (0–10 Hz) ground-motion simulations of this earthquake. A hybrid kinematic source is developed in which the final slip distribution combines a prescribed asperity model based on Interferometric Synthetic Aperture Radar data (as a source for low-frequency radiation) and a stochastic part (as a source for high-frequency radiation), which introduces spatial heterogeneities to the prescribed asperity model. The numerical approach is first validated by modeling the well-recorded 1994 Northridge earthquake before modeling the Menyuan earthquake. The simulated ground motion is compared with the only observed strong-motion station record, as well as with empirical Next Generation Attenuation-West2 ground-motion models. Then, topography effect in Menyuan earthquake is studied in detail. The simulated ground motions with and without surface topography indicate that the topography tends to focus and scatter the seismic wavefield, resulting in amplification of the ground shaking. The results show a significant correlation between the peak ground velocity (PGV) and topography. The PGV amplification caused by topography effects is period dependent, and its peak amplification reaches up to 50% within a typical resonance period (1–2 s). It could be inferred that the railway bridge probably vibrated in resonance and suffered severe damage owing to the amplified long-period ground motion caused by the topography.

Ground-motion simulations using two-dimensional convolution condition adversarial neural network(2D-cGAN)

In this paper, an integrated framework based on conditional adversarial neural network (cGAN) is established to simulate ground motions for earthquake scenarios with different magnitude, distance, and local site conditions. A ground motion dataset is created for training the network, within which most data are observed accelerograms collected from PEER and gaps for certain magnitude-site conditions are filled with accelerograms simulated using stochastic finite-fault modeling. During the learning of cGAN, the dataset is classified first with multi-labels according to local site conditions, and the multi-labels are set to be the conditional information Y for the network. Effects of using one-dimensional convolution (Conv1D) and two-dimensional convolution (Conv2D) in cGAN are tested in terms of the time-domain and frequency-domain characteristics of the generated ground motion. The test proves the strengths of Conv2D in capturing high-dimensional temporal and spectral characteristics from one-dimensional time series of ground motion. Ground motions generated using 2D-cGAN network are compared to the measures predicted by widely-used ground motion prediction equations, through which the reliability of 2D-cGAN network on ground motion simulation is verified.

Simulation of strong ground motions from 2016 Kumamoto (Mw 7.1), Japan, earthquake using modified hybrid technique

Simulation of strong ground motions from 2016 Kumamoto (Mw 7.1), Japan, earthquake using modified hybrid technique

A Physical-based Spectrum-compatible Ground Motion Simulation Method for Multi-Point Excitations

A Physical-based Spectrum-compatible Ground Motion Simulation Method for Multi-Point Excitations

Nationwide investigation of systematic site effects in New Zealand: Residual analysis of physicsbased ground motion simulations

Nationwide investigation of systematic site effects in New Zealand: Residual analysis of physicsbased ground motion simulations

Comparing and evaluating alternative methods to account for shallow site effects in hybrid broadband ground-motion simulations

Comparing and evaluating alternative methods to account for shallow site effects in hybrid broadband ground-motion simulations

Understanding Effects of Evolutionary Arias Intensity on Nonlinear Behavior of Hysteretic Systems and Liquefiable Grounds

ABSTRACT The effects of evolutionary Arias intensity are thoroughly investigated based on ground motion simulation and nonlinear dynamic response. A new methodology is developed to generate a series of spectral-equivalent synthetic motions with different energy accumulation paths using wavelet packets. Systematic studies are performed on dynamic responses of hysteretic systems and liquefiable grounds using the simulated motions and actual recordings. An attempt is made to develop the relationship between liquefaction-induced deformation and shaking intensity rate which is used to quantify the rate of Arias intensity accumulation. The results indicate the need of considering evolutionary Arias intensity in nonlinear dynamic analysis.

Stochastic ground motion simulation of the 26 September 2019 Mw 5.8 Silivri (Istanbul) earthquake

Stochastic ground motion simulation of the 26 September 2019 Mw 5.8 Silivri (Istanbul) earthquake

Evaluation of the Inter-frequency Correlation of New Zealand CyberShake Crustal Earthquake Simulations

The inter-frequency correlation of ground-motion residuals is related to the width of peaks and troughs in the ground-motion spectra (either response spectra or Fourier amplitude spectra; FAS) and is therefore an essential component of ground-motion simulations for representing the variability of structural response. As such, this component of the simulations requires evaluation and validation when the intended application is seismic fragility and seismic risk. This article evaluates the CyberShake NZ [1] crustal earthquake ground-motion simulations for their inter-frequency correlation, including comparisons with an empirical model developed from a global catalogue of shallow crustal earthquakes in active tectonic regions, and with results from similar simulations (SCEC CyberShake; [2]). Compared with the empirical model, the CyberShake NZ simulations have a satisfactory level of total inter-frequency correlation between the frequencies 0.1 – 0.25 Hz. At frequencies above 0.25 Hz, the simulations have lower (statistically significant at 95% confidence level) total inter-frequency correlation than the empirical model and therefore require calibration. To calibrate the total correlation, it is useful to focus on the correlation of the residual components. The between-event residual correlations, physically related to source effects (e.g., stress drop) which drive ground motions over a broad frequency range, are low at frequencies greater than about 0.25 Hz. Modifications to the cross-correlation between source parameters in the kinematic rupture generator can improve the inter-frequency correlations in this range [3]. The between-site residual correlations, which represents the correlation between frequencies of the systematic site amplification deviations, are larger (statistically significant at 95% confidence level) than the empirical model for frequencies less than about 0.5 Hz. We postulate that this relates to the relative simplicity of site amplification methods in the simulations, which feature less variability than the amplification observed in the data. Additional insight would be gained from future evaluations accounting for repeatable path and basin effects, using simulations with refined or alternative seismic velocity models, and using simulations with a higher crossover frequency to deterministic methods (e.g., 1 Hz or higher).

Findings from a decade of ground motion simulation validation research and a path forward

Simulated ground motions have the potential to advance seismic hazard assessments and structural response analyses, particularly for conditions with limited recorded ground motions such as large magnitude earthquakes at short source-to-site distances. However, rigorous validation of simulated ground motions is needed for hazard analysts, practicing engineers, or regulatory bodies to be confident in their use. A decade ago, validation exercises were mainly limited to comparisons of simulated-to-observed waveforms and median values of spectral accelerations for selected earthquakes. The Southern California Earthquake Center (SCEC) Ground Motion Simulation Validation (GMSV) group was formed to increase coordination between simulation modelers and research engineers with the aim of devising and applying more effective methods for simulation validation. Here, we summarize what has been learned in over a decade of GMSV activities, principally reflecting the views of the SCEC research community but also extending our findings and suggestions for a path forward to broader United States and worldwide simulation validation efforts. We categorize different validation methods according to their approach and the metrics considered. Two general approaches are to compare validation metrics from simulations to those from historical records or to those from semi-empirical models. Validation metrics are categorized into ground motion characteristics and structural responses. We discuss example validation studies that have been impactful in the past decade and suggest future research directions. Key lessons learned are that validation is application-specific, our outreach and dissemination need improvement, and much validation-related research remains unexplored.

Site‐specific response spectra developed by considering near‐fault motion with finite‐fault simulation in Taiwan

AbstractA new methodology is proposed for developing a scenario‐based site‐specific response spectrum (RS) considering near‐fault effects in Taiwan. First, source parameters, together with reference rock site conditions, are defined according to the available geological and geophysical information at a target site close to a potential active fault in northern Taiwan. Secondly, the scenario‐based response spectrum for a reference rock site condition is developed theoretically through an empirical approach by using a ground motion prediction equation (GMPE). The effect of the pulse period and the occurrence probability of near‐fault pulse‐like ground motion on RS is evaluated by using the ground motion simulation (GMS) technique, in which the stochastic finite‐fault simulation method is validated and applied for evaluating velocity pulse. Third, site‐specific site amplification is incorporated into RS through a site transfer function calculated from the measured horizontal‐to‐vertical Fourier spectral ratio through the microtremor (MHVR) of the target site. Finally, the design spectrum of the target site is compared with the derived site‐specific RS to evaluate the impact of the neighbor fault on the structure of the target site.

City-scale buildings damage estimation based on broadband physics-based ground motion simulation of 2021 Ms 6.4 Yangbi, China, earthquake

This article proposed a computational workflow for city-scale building damage estimation based on broadband physics-based ground motion simulation. The dynamic stiffness matrix method in frequency-wavenumber domain is employed for broadband physics-based ground motion simulation of finite fault along with site response correction using equivalent-linear site response analysis approach. With simulated ground motion, seismic response of buildings, using multi-degree of freedom model, is simulated using nonlinear time history analysis, and building damage is evaluated based on a trilinear backbone curve of story’s nonlinear force-drift model. Main advantage of the framework lies in the employed dynamic stiffness matrix method for ground motion simulation, which can efficiently generate broadband ground motions in perfect parallel and naturally capture the physics of finite fault source, propagation path, and spatial variability characteristics of ground motion. To demonstrate the salient features of proposed workflow, the 2021 Ms 6.4 Yangbi earthquake is simulated with frequency resolution up to 20 Hz, and seismic damage of buildings in Yangbi county are estimated. Results show that most traditional wood-adobe structures suffer moderate to severe damage, and engineered seismic buildings (mostly RC frame) in Yangbi county suffer minor damage, which agrees with field investigation results.

Ground motion simulations of the 1887 Pinal de Amoles (MW = 5.53) and the 1989 Landa de Matamoros (MW = 4.94) earthquakes, Querétaro, Mexico

Ground motions characteristics of the 1887 Pinal de Amoles (MW = 5.53) and the 1989 Landa de Matamoros (MW = 4.94) Querétaro earthquakes were studied. For this purpose, the specific barrier model (SBM) was implemented in the context of the stochastic ground motion representation of earthquakes. The SBM was calibrated by modeling the peak ground acceleration (PGA) and the Fourier acceleration spectra (FAS) of the 11 May 2016 (MW = 4.80) Guadalajara earthquake. The calibration results showed that the SBM and selected source and path parameters were able to reproduce synthetic PGA and spectra in good agreement with observed waveforms; in particular, a stress drop of 160 bars fits the results better. Several rupture scenarios for the 1887 and 1989 events were performed by obtaining synthetic seismograms considering different values of stress drop (10, 30, 50, 100, 150, 200, 300, and 500 bars). For a typical stress-drop value of 100 bars, the PGA at distances of 10 and 200 km are in the following intervals: 2.57–295 cm/s2 and 1.72–186 cm/s2 for the Pinal de Amoles and Landa de Matamoros earthquakes, respectively. The results obtained in this study contribute toward a better understanding of strong ground motions in the region.

Construction and validation of a simulated ground motion dataset for Turkey

Construction and validation of a simulated ground motion dataset for Turkey

Earthquake response of reinforced concrete frames with infill and active external confinement: Tests and dataset

One option to retrofit reinforced concrete (RC) frames is the construction of infill walls. Infill increases lateral strength and stiffness but tends to reduce drift capacity relative to bare frames. Few studies have quantified the reductions in drift demand attributable to infills prior to failure. This report summarizes data from experiments designed to compare drift demands of frames with and without infill. Included data come from two experimental programs completed at Purdue University which focused on the in-plane dynamic response of reduced-scale, non-ductile RC frames to uniaxial simulated earthquake ground motions. 254 dynamic tests were conducted on bare frames, frames with masonry infill walls, and frames with timber infill walls. In 11 of 14 test series, active confinement was applied to columns using external post-tensioned reinforcement. The complete dataset is open-access online on Zenodo, DOI: 10.5281/zenodo.6954967.

Stochastic simulation of earthquake ground motions based on improved finite-fault model

In the seismic reliability analysis of engineering structures, it is often necessary to adopt stochastic ground motions as inputs. However, the current methods used to generate stochastic samples, such as the spectral representation method, the spectral transfer method, the dynamic source method, the physical source method, and the comprehensive method, etc., are not very convincing since they do not contain the complete information of seismic occurrence and propagation. In this study, an improved finite-fault model for stochastic simulation of ground motions is proposed. Compared to existing stochastic finite-fault model, the improved model considers the propagation law of phase spectrum, local site effect, and the impact of wave velocity on the arrival time of seismic waves. Besides, identification and statistics of model parameters are carried out based on ground motion records. Reasonable samples of stochastic ground motions are then obtained. In addition, parameter sensitivity analysis is conducted to determine critical random variables, which reduces the complexity of stochastic simulation. Simulation results are compared with recorded accelerograms from the 1999 Chi-Chi earthquake. It is shown that the improved stochastic finite-fault model is reliable, and the acceleration response spectra of simulated samples are consistent with those of station records collected at various site classes and the design spectra.

Long-period directivity pulses of strong ground motion during the 2023 Mw7.8 Kahramanmaraş earthquake

Damages due to large earthquakes are influenced by broadband source effects that remain enigmatic. Here we develop a broadband (0–10 Hz) source model of the disastrous 2023 Mw7.8 Kahramanmaraş, Türkiye, earthquake by modeling recordings of 100 stations. The model combines coherent and incoherent rupture propagation at low and high frequencies, respectively. We adopt a planar 300 km long kinked fault geometry from geology and pre-constrain the slip model from seismic and geodetic data. We demonstrate that the southwestward rupture propagation was delayed by ~15 s and that the observed strong waveform pulses can be explained by the directivity effect due to a specific combination of the coherent and incoherent components. We show that even a rough estimate of major rupture parameters makes the ground motion simulations of such large events possible, and may thus improve the efficiency of rapid, physics-based, shaking estimation for emergency response and seismic hazard assessment.

Ground motion prediction equation for NW Himalaya and its surrounding region

An attenuation relationship, also known as a Ground Motion Prediction Equation (GMPE), has been developed for the Northwest Himalaya and its surrounding region. This GMPE utilizes strong motion data recorded by two networks: the National Center for Seismology Network and the strong motion network installed by Indian Institute of Technology Roorkee named PESMOS. For the development of this GMPE, 309 strong motion records from 86 earthquakes that occurred between 2005 and 2021 were considered. The selected earthquakes have magnitudes ranging from 3.0 to 6.9. In this study, the average of Peak Ground Acceleration (PGA) of two horizontal components was used to develop the new attenuation relationship. A multi-regression model was chosen for the analysis. The proposed attenuation relationship is.Log10 PGA = 1.889 + 0.3996 × M - 0.95736 log10 (HD + exp (0.4114 × M)) ± 0.3646Where, PGA is peak horizontal acceleration in gal of strong ground motion, M is the magnitude, and HD is the hypocentral distance from the source. The standard error of the proposed relationship is 0.3646. This newly developed attenuation relationship holds significance for various applications, including site-specific studies, seismic hazard estimation, ground motion simulation, earthquake early warning (EEW), and engineering applications. It provides valuable insights into the behavior of ground motion in the Northwest Himalayan region, allowing for better preparedness and mitigation strategies against seismic hazards in the area.

ANN-based ground motion model for Turkey using stochastic simulation of earthquakes

SUMMARY Turkey is characterized by a high level of seismic activity attributed to its complex tectonic structure. The country has a dense network to record earthquake ground motions; however, to study previous earthquakes and to account for potential future ones, ground motion simulations are required. Ground motion simulation techniques offer an alternative means of generating region-specific time-series data for locations with limited seismic networks or regions with seismic data gaps, facilitating the study of potential catastrophic earthquakes. In this research, a local ground motion model (GMM) for Turkey is developed using region-specific simulated records, thus constructing a homogeneous data set. The simulations employ the stochastic finite-fault approach and utilize validated input-model parameters in distinct regions, namely Afyon, Erzincan, Duzce, Istanbul and Van. To overcome the limitations of linear regression-based models, artificial neural network is used to establish the form of equations and coefficients. The predictive input parameters encompass fault mechanism (FM), focal depth (FD), moment magnitude (Mw), Joyner and Boore distance (RJB) and average shear wave velocity in the top 30 m (Vs30). The data set comprises 7359 records with Mw ranging between 5.0 and 7.5 and RJB ranging from 0 to 272 km. The results are presented in terms of spectral ordinates within the period range of 0.03–2.0 s, as well as peak ground acceleration and peak ground velocity. The quantification of the GMM uncertainty is achieved through the analysis of residuals, enabling insights into inter- and intra-event uncertainties. The simulation results and the effectiveness of the model are verified by comparing the predicted values of ground motion parameters with the observed values recorded during previous events in the region. The results demonstrate the efficacy of the proposed model in simulating physical phenomena.