Ground-Motion Model for Crustal Events in Italy by Applying the Multisource Geographically Weighted Regression (MS-GWR) Method

ABSTRACT In this article, we implement a new approach to calibrate ground-motion models (GMMs) characterized by spatially varying coefficients, using the calibration dataset of an existing GMM for crustal events in Italy. The model is developed in the methodological framework of the multisource geographically weighted regression (MS-GWR, Caramenti et al., 2020), which extends the theory of multiple linear regression to the case with model coefficients that are spatially varying, thus allowing for capturing the multiple sources of nonstationarity in ground motion related to event and station locations. In this way, we reach the aim of regionalizing the ground motion in Italy by specializing the model in a nonergodic framework. Such an attempt at regionalization also addresses the purpose of capturing the regional effects in the modeling, which is needed for the Italian country, where ground-motion properties vary significantly across space. Because the proposed model relies on the italian GMM (ITA18) (Lanzano et al., 2019) dataset and functional form, it could be considered the ITA18 nonstationary version, thus allowing one to predict peak ground acceleration and velocity, as well as 36 ordinates of the 5%-damped acceleration response spectra in the period interval T=0.01–10 s. The resulting MS-GWR model shows an improved ability to predict the ground motion locally, compared with stationary ITA18, leading to a significant reduction of the total variability at all periods of about 15%–20%. The article also provides scenario-dependent uncertainties associated with the median predictions to be used as a part of the epistemic uncertainty in the context of probabilistic seismic hazard analyses. Results show that the approach is promising for improving the model predictions, especially on densely sampled areas, although further studies are necessary to resolve the observed trade-off inherent to site and path effects, which limits their physical interpretation.

Download Full-text

A Non-Ergodic Effective Amplitude Ground-Motion Model for California

10.21203/rs.3.rs-287658/v1 ◽

2021 ◽

Author(s):

Grigorios Lavrentiadis ◽

Norman A. Abrahamson ◽

Nicolas M. Kuehn

Keyword(s):

Standard Deviation ◽

Ground Motion ◽

Epistemic Uncertainty ◽

Amplitude Spectrum ◽

Time History ◽

Motion Model ◽

Small Magnitude ◽

Varying Coefficients ◽

Ground Motion Model ◽

Systematic Effects

Abstract A new non-ergodic ground-motion model (GMM) for effective amplitude spectral (EAS) values for California is presented in this study. EAS, which is defined in Goulet et al. (2018), is a smoothed rotation-independent Fourier amplitude spectrum of the two horizontal components of an acceleration time history. The main motivation for developing a non-ergodic EAS GMM, rather than a spectral acceleration GMM, is that the scaling of EAS does not depend on spectral shape, and therefore, the more frequent small magnitude events can be used in the estimation of the non-ergodic terms. The model is developed using the California subset of the NGAWest2 dataset Ancheta et al. (2013). The Bayless and Abrahamson (2019b) (BA18) ergodic EAS GMM was used as backbone to constrain the average source, path, and site scaling. The non-ergodic GMM is formulated as a Bayesian hierarchical model: the non-ergodic source and site terms are modeled as spatially varying coefficients following the approach of Landwehr et al. (2016), and the non-ergodic path effects are captured by the cell-specific anelastic attenuation attenuation following the approach of Dawood and Rodriguez-Marek (2013). Close to stations and past events, the mean values of the non-ergodic terms deviate from zero to capture the systematic effects and their epistemic uncertainty is small. In areas with sparse data, the epistemic uncertainty of the non-ergodic terms is large, as the systematic effects cannot be determined. The non-ergodic total aleatory standard deviation is approximately 30 to 40% smaller than the total aleatory standard deviation of BA18. This reduction in the aleatory variability has a significant impact on hazard calculations at large return periods. The epistemic uncertainty of the ground motion predictions is small in areas close to stations and past event.

Download Full-text

A Comparison of Nonergodic Ground-Motion Models based on Geographically Weighted Regression and the Integrated Nested Laplace Approximation

10.31224/osf.io/bvjuy ◽

2021 ◽

Author(s):

Nicolas Kuehn

Keyword(s):

Ground Motion ◽

Geographically Weighted Regression ◽

Seismic Hazard Assessment ◽

Predictive Performance ◽

Laplace Approximation ◽

Weighted Regression ◽

Integrated Nested Laplace Approximation ◽

Motion Models ◽

Spatially Varying ◽

Ground Motion Models

Different nonergodic Ground-Motion Models based on spatially varying coefficient models are compared for ground-motion data in Italy. The models are based different methodologies: Multi-source geographically weighted regression (Caramenti et al., 2020), and Bayesian hierarchical models estimated with the integrated nested Laplace approximation (Rue et al., 2009). The different models are compared in terms of their predictive performance, their spatial coefficients, and their predictions. Models that include spatial terms perform slightly better than a simple base model that includes only event and station terms, in terms of out-of sample error based on cross-validation. The Bayesian spatial models have slightly lower generalization error, which can be attributed to the fact that they can include random effects for events and stations. The different methodologies give rise to different dependencies of the spatially varying terms on event and station locations, leading to between-model uncertainty in their predictions, which should be accommodated in a nonergodic seismic hazard assessment.

Download Full-text

A Nonergodic Ground‐Motion Model for California with Spatially Varying Coefficients

Bulletin of the Seismological Society of America ◽

10.1785/0120160118 ◽

2016 ◽

Vol 106 (6) ◽

pp. 2574-2583 ◽

Cited By ~ 31

Author(s):

Niels Landwehr ◽

Nicolas M. Kuehn ◽

Tobias Scheffer ◽

Norman Abrahamson

Keyword(s):

Ground Motion ◽

Motion Model ◽

Varying Coefficients ◽

Ground Motion Model ◽

Spatially Varying

Download Full-text

Ground-motion relations for eastern North America

Bulletin of the Seismological Society of America ◽

10.1785/bssa0850010017 ◽

1995 ◽

Vol 85 (1) ◽

pp. 17-30 ◽

Cited By ~ 27

Author(s):

Gail M. Atkinson ◽

David M. Boore

Keyword(s):

Ground Motion ◽

Ground Motions ◽

Response Spectra ◽

Model Parameters ◽

Eastern North America ◽

Motion Model ◽

Ground Acceleration ◽

Ground Motion Model ◽

Definition Of ◽

Validation Of Results

Abstract Predictive relations are developed for ground motions from eastern North American earthquakes of 4.0 ≦ M ≦ 7.25 at distances of 10 ≦ R ≦ 500 km. The predicted parameters are response spectra at frequencies of 0.5 to 20 Hz, and peak ground acceleration and velocity. The predictions are derived from an empirically based stochastic ground-motion model. The relations differ from previous work in the improved empirical definition of input parameters and empirical validation of results. The relations are in demonstrable agreement with ground motions from earthquakes of M 4 to 5. There are insufficient data to adequately judge the relations at larger magnitudes, although they are consistent with data from the Saguenay (M 5.8) and Nahanni (M 6.8) earthquakes. The underlying model parameters are constrained by empirical data for events as large as M 6.8.

Download Full-text

Ground Motion Model for the Vertical-to-Horizontal (V/H) Ratios of PGA, PGV, and Response Spectra

Earthquake Spectra ◽

10.1193/100614eqs151m ◽

2016 ◽

Vol 32 (2) ◽

pp. 951-978 ◽

Cited By ~ 36

Author(s):

Yousef Bozorgnia ◽

Kenneth W. Campbell

Keyword(s):

Ground Motion ◽

Site Response ◽

Hanging Wall ◽

Strong Dependence ◽

Response Spectra ◽

Peak Ground Velocity ◽

Motion Model ◽

Fault Rupture ◽

Ground Acceleration ◽

Ground Motion Model

We present a ground motion model (GMM) for the vertical-to-horizontal (V/H) ratios of peak ground acceleration, peak ground velocity, and 5%-damped pseudo-acceleration response spectra at periods ranging from 0.01 s to 10 s. The V/H GMM includes formulations for the median V/H ratio and for the aleatory within-event, between-event, and total standard deviations. The V/H model is based on the GMMs we have developed for the vertical and “average” horizontal components of ground motion using a mathematical formation that accounts for the correlation between these two components. We validated the V/H model against the NGA-West2 empirical database. We consider our V/H model to be valid for worldwide shallow crustal earthquakes in active tectonic regions for moment magnitudes ranging from 3.3 to 8.5, depending on the style of faulting, and for fault rupture distances ranging from 0 km to 300 km. Our V/H model incorporates period-dependent effects of magnitude saturation, style of faulting, hypocentral depth, fault-rupture dip, geometric attenuation, regionally dependent anelastic attenuation and site response, hanging-wall geometry, and magnitude-dependent between-event and within-event aleatory variabilities. The V/H ratios predicted from the model show a strong dependence on spectral period and site response.

Download Full-text

Vertical Ground Motion Model for PGA, PGV, and Linear Response Spectra Using the NGA-West2 Database

Earthquake Spectra ◽

10.1193/072814eqs121m ◽

2016 ◽

Vol 32 (2) ◽

pp. 979-1004 ◽

Cited By ~ 31

Author(s):

Yousef Bozorgnia ◽

Kenneth W. Campbell

Keyword(s):

Ground Motion ◽

Response Spectra ◽

Peak Ground Velocity ◽

Motion Model ◽

Acceleration Response ◽

Ground Acceleration ◽

Ground Motion Model ◽

Crustal Earthquakes ◽

Active Tectonic ◽

Vertical Ground

We summarize the development of the NGA-West2 Bozorgnia-Campbell empirical ground motion model (GMM) for the vertical components of peak ground acceleration (PGA), peak ground velocity (PGV), and 5%-damped elastic pseudo-absolute acceleration response spectra (PSA) at vertical periods ranging from 0.01 s to 10 s. In the development of the vertical GMM, similar to our 2014 horizontal GMM, we used the extensive PEER NGA-West2 worldwide database. We consider our new vertical GMM to be valid for shallow crustal earthquakes in active tectonic regions for magnitudes ranging from 3.3 to 7.5–8.5, depending on the style of faulting, and for distances as far as 300 km from the fault.

Download Full-text

Lessons Learned from Applying Varying Coefficient Model to Controlled Simulation Datasets

10.21203/rs.3.rs-947112/v1 ◽

2021 ◽

Author(s):

Xiaofeng Meng ◽

Christine Goulet

Keyword(s):

Ground Motion ◽

Epistemic Uncertainty ◽

Velocity Model ◽

Lessons Learned ◽

Point Sources ◽

Varying Coefficient Model ◽

Varying Coefficient ◽

Varying Coefficients ◽

3D Velocity Model ◽

Spatially Varying

Abstract The development of site- and path-specific (i.e., non-ergodic) ground motion models (GMMs) can drastically improve the accuracy of probabilistic seismic hazard analyses (PSHA). The Varying Coefficient Model (VCM) is a novel technique for developing non-ergodic GMMs, which puts epistemic uncertainty into spatially varying coefficients. The coefficients at nearby locations are correlated by placing a Gaussian process prior on them. The correlation structure is determined by the data, and later used to predict coefficients and their epistemic uncertainties at new locations. It is important to carefully verify the technique before its results can be accepted by the engineering community. In this study, we used a series of simulation-based controlled ground motion datasets from CyberShake to test a modified VCM technique, which partitions the epistemic uncertainty into spatially varying source, site and path terms. Because the simulation parameters (inputs) are known, it is straightforward to verify what is recovered by the VCM from CyberShake simulation. We find that the site effects in CyberShake datasets can be reliably recovered by the VCM. However, the densely-located self-similar events in CyberShake datasets lead to large correlation lengths, which violates the isotropic assumption underlying the method and prevents the VCM from capturing the genuine source effects. For path effects, cell-specific attenuation approaches fail to recover the anelastic attenuation pattern of the 3D velocity model, most likely due to inappropriate assumption of point sources and straight-line wave propagation. Instead, a midpoint approach that only considers the aggregated path effects can better recover the strong attenuation within basins by fixing the correlation length of path effects. Lessons learned in this study not only provide important guidance for future applications of VCM to both simulation and empirical datasets, but also help further development of the technique, notably for the recovery of path effects.

Download Full-text

Framework for a Ground-Motion Model for Induced Seismic Hazard and Risk Analysis in the Groningen Gas Field, The Netherlands

Earthquake Spectra ◽

10.1193/082916eqs138m ◽

2017 ◽

Vol 33 (2) ◽

pp. 481-498 ◽

Cited By ~ 46

Author(s):

Julian J. Bommer ◽

Peter J. Stafford ◽

Benjamin Edwards ◽

Bernard Dost ◽

Ewoud van Dedem ◽

...

Keyword(s):

Seismic Hazard ◽

Ground Motion ◽

Quantitative Estimation ◽

Epistemic Uncertainty ◽

Induced Earthquakes ◽

Gas Field ◽

Small Magnitude ◽

Ground Motion Model ◽

Hazard And Risk ◽

Groningen Gas Field

The potential for building damage and personal injury due to induced earthquakes in the Groningen gas field is being modeled in order to inform risk management decisions. To facilitate the quantitative estimation of the induced seismic hazard and risk, a ground motion prediction model has been developed for response spectral accelerations and duration due to these earthquakes that originate within the reservoir at 3 km depth. The model is consistent with the motions recorded from small-magnitude events and captures the epistemic uncertainty associated with extrapolation to larger magnitudes. In order to reflect the conditions in the field, the model first predicts accelerations at a rock horizon some 800 m below the surface and then convolves these motions with frequency-dependent nonlinear amplification factors assigned to zones across the study area. The variability of the ground motions is modeled in all of its constituent parts at the rock and surface levels.

Download Full-text

Probabilistic seismic hazard analysis using the logic tree approach – Patna district (India)

Natural Hazards and Earth System Science ◽

10.5194/nhess-19-2097-2019 ◽

2019 ◽

Vol 19 (10) ◽

pp. 2097-2115 ◽

Cited By ~ 1

Author(s):

Panjamani Anbazhagan ◽

Ketan Bajaj ◽

Karanpreet Matharu ◽

Sayed S. R. Moustafa ◽

Nassir S. N. Al-Arifi

Keyword(s):

Epistemic Uncertainty ◽

Hazard Analysis ◽

Response Spectra ◽

Maximum Magnitude ◽

Logic Tree ◽

Ground Acceleration ◽

Incremental Method ◽

Seismicity Parameters ◽

Hazard Response ◽

Tree Approach

Abstract. Peak ground acceleration (PGA) and study area (SA) distribution for the Patna district are presented considering both the classical and zoneless approaches through a logic tree framework to capture the epistemic uncertainty. Seismicity parameters are calculated by considering completed and mixed earthquake data. Maximum magnitude is calculated using three methods, namely the incremental method, Kijko method, and regional rupture characteristics approach. The best suitable ground motion prediction equations (GMPEs) are selected by carrying out an “efficacy test” using log likelihood. Uniform hazard response spectra have been compared with Indian standard BIS 1893. PGA varies from 0.38 to 0.30 g from the southern to northern periphery considering 2 % probability of exceedance in 50 years.

Download Full-text

Preliminary results of ground-motion characteristics

Annals of Geophysics ◽

10.4401/ag-6121 ◽

2012 ◽

Vol 55 (4) ◽

Author(s):

Francesca Bozzoni ◽

Carlo Giovanni Lai ◽

Laura Scandella

Keyword(s):

Ground Motion ◽

Site Response ◽

Response Spectrum ◽

Field Tests ◽

Response Spectra ◽

Ground Acceleration ◽

Preliminary Results ◽

Emilia Earthquake ◽

Particle Orbit ◽

2012 Emilia Earthquake

The preliminary results are presented herein for the engineering applications of the characteristics of the ground motion induced by the May 20, 2012, Emilia earthquake. Shake maps are computed to provide estimates of the spatial distribution of the induced ground motion. The signals recorded at the Mirandola (MRN) station, the closest to the epicenter, have been processed to obtain acceleration, velocity and displacement response spectra. Ground-motion parameters from the MRN recordings are compared with the corresponding estimates from recent ground-motion prediction equations, and with the spectra prescribed by the current Italian Building Code for different return periods. The records from the MRN station are used to plot the particle orbit (hodogram) described by the waveform. The availability of results from geotechnical field tests that were performed at a few sites in the Municipality of Mirandola prior to this earthquake of May 2012 has allowed preliminary assessment of the ground response. The amplification effects at Mirandola are estimated using fully stochastic site-response analyses. The seismic input comprises seven actual records that are compatible with the Italian code-based spectrum that refers to a 475-year return period. The computed acceleration response spectrum and the associated dispersion are compared to the spectra calculated from the recordings of the MRN station. Good agreement is obtained for periods up to 1 s, especially for the peak ground acceleration. For the other periods, the spectral acceleration of the MRN recordings exceeds that of the computed spectra.<br />

Download Full-text