Spectral damping scaling factors for horizontal components of ground motions from subduction earthquakes using NGA-Subduction data

This article develops global models of damping scaling factors (DSFs) for subduction zone earthquakes that are functions of the damping ratio, spectral period, earthquake magnitude, and distance. The Next Generation Attenuation for subduction earthquakes (NGA-Sub) project has developed the largest uniformly processed database of recorded ground motions to date from seven subduction regions: Alaska, Cascadia, Central America and Mexico, South America, Japan, Taiwan, and New Zealand. NGA-Sub used this database to develop new ground motion models (GMMs) at a reference 5% damping ratio. We worked with the NGA-Sub project team to develop an extended database that includes pseudo-spectral accelerations (PSA) for 11 damping ratios between 0.5% and 30%. We use this database to develop parametric models of DSF for both interface and intraslab subduction earthquakes that can be used to adjust any subduction GMM from a reference 5% damping ratio to other damping ratios. The DSF is strongly influenced by the response spectral shape and the duration of motion; therefore, in addition to the damping ratio, the median DSF model uses spectral period, magnitude, and distance as surrogate predictor variables to capture the effects of the spectral shape and the duration of motion. We also develop parametric models for the standard deviation of DSF. The models presented in this article are for the RotD50 horizontal component of PSA and are compared with the models for shallow crustal earthquakes in active tectonic regions. Some noticeable differences arise from the considerably longer duration of interface records for very large magnitude events and the enriched high-frequency content of intraslab records, compared with shallow crustal earthquakes. Regional differences are discussed by comparing the proposed global models with the data from each subduction region along with recommendations on the applicability of the models.

Download Full-text

Hazard-consistent seismic losses and collapse capacities for light-frame wood buildings in California and Cascadia

Bulletin of Earthquake Engineering ◽

10.1007/s10518-021-01258-y ◽

2021 ◽

Author(s):

Robert E. Chase ◽

Abbie B. Liel ◽

Nicolas Luco ◽

Zach Bullock

Keyword(s):

Seismic Hazard ◽

Ground Motion ◽

Seismic Risk ◽

Ground Motions ◽

Spectral Shape ◽

Economic Losses ◽

Frequency Content ◽

Crustal Earthquakes ◽

Design Values ◽

American Society

AbstractWe evaluate the seismic performance of modern seismically designed wood light-frame (WLF) buildings, considering regional seismic hazard characteristics that influence ground motion duration and frequency content and, thus, seismic risk. Results show that WLF building response correlates strongly with ground motion spectral shape but weakly with duration. Due to the flatter spectral shape of ground motions from subduction events, WLF buildings at sites affected by these earthquakes may experience double the economic losses for a given intensity of shaking, and collapse capacities may be reduced by up to 50%, compared to those at sites affected by crustal earthquakes. These differences could motivate significant increases in design values at sites affected by subduction earthquakes to achieve the uniform risk targets of the American Society of Civil Engineers (ASCE) 7 standard.

Download Full-text

Comparison of Near-Fault Velocity Pulse-Like Ground Motions from the 2018 Mw 6.4 Hualien, Taiwan, Earthquake with the Next Generation Attenuation (NGA)-West2 Ground-Motion Models and Directivity Models

Bulletin of the Seismological Society of America ◽

10.1785/0120200141 ◽

2021 ◽

Author(s):

Xiaofen Zhao ◽

Zengping Wen ◽

Junju Xie ◽

Quancai Xie ◽

Kuo-En Ching

Keyword(s):

Ground Motion ◽

Hazard Analysis ◽

Ground Motions ◽

Spectral Shape ◽

Next Generation ◽

Motion Models ◽

Near Fault ◽

Short Period ◽

Shape Curve ◽

Ground Motion Models

ABSTRACT Pulse-like ground motions cause severe damage in structures at certain periods. Hence, pulse effects need to be considered during probabilistic seismic hazard analysis and seismic design in the near-fault region. Traditional ground-motion models used to quantify the hazard posed by pulse-like ground motions may underestimate them, but they are relatively suitable for describing the residual ground motions after extracting pulses. Nevertheless, the applicability of Next Generation Attenuation-West2 Project (NGA-West2) models to pulse and residual ground motions has not been evaluated. Moreover, the applicability of recently developed directivity models, including the Shahi and Baker (2011; hereafter, SB2011), Chang et al. (2018; hereafter, Chang2018), and Rupakhety et al. (2011; hereafter, Rupakhety2011) models, has not been investigated for this event. Here, based on the abundance of pulse-like ground motions recorded during the Mw 6.4 Hualien earthquake, the applicability of NGA-West2 models and directivity models was quantitatively evaluated. In summary, (1) The applicability of NGA-West2 models to the observed original and residual ground motions varies significantly at different periods. The suggests that NGA-West2 models overestimate the original and residual ground motions for short periods (T<1.0 s), but are suitable for describing the residual ground motions yet underestimate the original ground motions for long periods (T≥1.0 s). (2) Pulse periods and amplification bands due to pulses are unusually larger than previous events. Similar to the Chang2018 model, the plateau of this event starts and ends at the periods of 0.70 and 1.1 times the pulse period. However, the Chang2018 and SB2011 models underestimate the constant ordinate of this plateau. Spectral ordinates of the spectral shape curve due to pulses for the short period (∼Tn<1.3 s) are smaller than the predictions from the Rupakhety2011 model. The trend was reversed for long periods (∼Tn>3.0 s). Compared with the Rupakhety2011 model, the peak location of the spectral shape curve is shifted to the long period. These results will be helpful for updating these models in the near future.

Download Full-text

The effect of spectral shape on damping modification factors

Earthquake Spectra ◽

10.1177/8755293020936691 ◽

2020 ◽

Vol 36 (4) ◽

pp. 2086-2111

Author(s):

Sebastián Miranda ◽

Eduardo Miranda ◽

Juan Carlos de la Llera

Keyword(s):

Statistical Analysis ◽

Significant Influence ◽

Response Spectrum ◽

Ground Motions ◽

Damping Ratio ◽

Earthquake Magnitude ◽

Spectral Shape ◽

Site Class ◽

Shape Metrics ◽

Different Levels

The main objective of this study is to investigate the effect of spectral shape on damping modification factors η used in equivalent static and response spectrum analyses of structures with damping ratios that are different from 5% critical damping. Record-to-record variability of η is also evaluated through a statistical analysis of 5270 ground motions records from 1137 interface earthquakes recorded in Chile. The effect of spectral shape is studied using recently developed spectral shape metrics SaRatio and epsilon [Formula: see text] and evaluating their use as possible predictors for η. Similarly to previous investigations, this article also examines the effect of oscillator period, earthquake magnitude, and earthquake duration for different levels of damping ratio. Results suggest that SaRatio is an effective predictor of η, particularly for highly damped structures. However, results also indicate that for rock and firm sites, earthquake faulting mechanism and site class do not have a significant influence on η. A simple period-independent regression model for η as a function of SaRatio and damping ratio is proposed. A comparison between median η from this study and those in current Chilean seismic codes shows that code factors are unconservative.

Download Full-text

Collapse Risk of Buildings in the Pacific Northwest Region due to Subduction Earthquakes

Earthquake Spectra ◽

10.1193/012114eqs011m ◽

2015 ◽

Vol 31 (4) ◽

pp. 2087-2115 ◽

Cited By ~ 28

Author(s):

Meera Raghunandan ◽

Abbie B. Liel ◽

Nicolas Luco

Keyword(s):

Pacific Northwest ◽

Ground Motions ◽

Cascadia Subduction Zone ◽

Subduction Earthquakes ◽

Crustal Earthquakes ◽

The Pacific ◽

Dynamic Analyses ◽

Nonlinear Dynamic Analyses ◽

Northwest Region ◽

Modern Building

Subduction earthquakes similar to the 2011 Japan and 2010 Chile events will occur in the future in the Cascadia subduction zone in the Pacific Northwest. In this paper, nonlinear dynamic analyses are carried out on 24 buildings designed according to outdated and modern building codes for the cities of Seattle, Washington, and Portland, Oregon. The results indicate that the median collapse capacity of the ductile (post-1970) buildings is approximately 40% less when subjected to ground motions from subduction, as compared to crustal earthquakes. Buildings are more susceptible to earthquake-induced collapse when shaken by subduction records (as compared to crustal records of the same intensity) because the subduction motions tend to be longer in duration due to their larger magnitude and the greater source-to-site distance. As a result, subduction earthquakes are shown to contribute to the majority of the collapse risk of the buildings analyzed.

Download Full-text

Effects of Deep Basins on Structural Collapse during Large Subduction Earthquakes

Earthquake Spectra ◽

10.1193/071916eqs114m ◽

2017 ◽

Vol 33 (3) ◽

pp. 963-997 ◽

Cited By ~ 12

Author(s):

Nasser A. Marafi ◽

Marc O. Eberhard ◽

Jeffrey W. Berman ◽

Erin A. Wirth ◽

Arthur D. Frankel

Keyword(s):

Pacific Northwest ◽

Ground Motions ◽

Sedimentary Basins ◽

Spectral Shape ◽

Hazard Maps ◽

Structural Collapse ◽

Subduction Earthquakes ◽

Long Duration ◽

The Pacific ◽

Spectral Accelerations

Deep sedimentary basins are known to increase the intensity of ground motions, but this effect is implicitly considered in seismic hazard maps used in U.S. building codes. The basin amplification of ground motions from subduction earthquakes is particularly important in the Pacific Northwest, where the hazard at long periods is dominated by such earthquakes. This paper evaluates the effects of basins on spectral accelerations, ground-motion duration, spectral shape, and structural collapse using subduction earthquake recordings from basins in Japan that have similar depths as the Puget Lowland basin. For three of the Japanese basins and the Puget Lowland basin, the spectral accelerations were amplified by a factor of 2 to 4 for periods above 2.0 s. The long-duration subduction earthquakes and the effects of basins on spectral shape combined, lower the spectral accelerations at collapse for a set of building archetypes relative to other ground motions. For the hypothetical case in which these motions represent the entire hazard, the archetypes would need to increase up to 3.3 times its strength to compensate for these effects.

Download Full-text

Ground motion prediction equations for significant duration using the KiK-net database

Earthquake Spectra ◽

10.1177/8755293020970971 ◽

2020 ◽

pp. 875529302097097

Author(s):

Mahdi Bahrampouri ◽

Adrian Rodriguez-Marek ◽

Russell A Green

Keyword(s):

Ground Motion ◽

Structural Engineering ◽

Ground Motions ◽

Motion Prediction ◽

Ground Motion Prediction ◽

Subduction Earthquakes ◽

Significant Duration ◽

Crustal Earthquakes ◽

Active Tectonic ◽

The Difference

Significant duration of strong shaking quantifies the length of time during which strong earthquake-induced shaking occurs at a given site. Significant duration has multiple applications in Geotechnical and Structural Engineering. However, while multiple ground motion prediction (GMPE) equations for duration exist for shallow crustal tectonic environments, at the time of this publication, there are few published models for predicting significant duration of subduction earthquakes. To address this need and to identify the difference between significant duration of motions resulting from earthquakes in different tectonic regimes, we develop predictive equations for significant duration applicable to interface and intraslab subduction earthquakes and shallow crustal earthquakes in active tectonic regimes using the KiK-net ground motion database. The GMPEs are applicable to earthquakes with M4 to 9. In addition, the influence of earthquake magnitude on duration due to path effects is captured in the proposed relationships. Based on the relationships proposed in this study, we note that the duration of ground motions from subduction earthquakes is longer than those of shallow crustal earthquakes that have similar magnitudes and distances. The predictions of duration for shallow crustal earthquakes in active tectonic regimes developed in this study are consistent with those from previous studies.

Download Full-text

An NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra

Earthquake Spectra ◽

10.1193/1.2894832 ◽

2008 ◽

Vol 24 (1) ◽

pp. 173-215 ◽

Cited By ~ 501

Author(s):

BrianS-J. Chiou ◽

Robert R. Youngs

Keyword(s):

Ground Motion ◽

Ground Motions ◽

Hanging Wall ◽

Response Spectra ◽

Horizontal Component ◽

Smooth Functions ◽

Soil Response ◽

New Model ◽

Crustal Earthquakes ◽

Aleatory Variability

We present a model for estimating horizontal ground motion amplitudes caused by shallow crustal earthquakes occurring in active tectonic environments. The model provides predictive relationships for the orientation-independent average horizontal component of ground motions. Relationships are provided for peak acceleration, peak velocity, and 5-percent damped pseudo-spectral acceleration for spectral periods of 0.01 to 10 seconds. The model represents an update of the relationships developed by Sadigh et. al. (1997) and incorporates improved magnitude and distance scaling forms as well as hanging-wall effects. Site effects are represented by smooth functions of average shear wave velocity of the upper 30 m ( VS30) and sediment depth. The new model predicts median ground motion that is similar to Sadigh et. al. (1997) at short spectral period, but lower ground motions at longer periods. The new model produces slightly lower ground motions in the distance range of 10 to 50 km and larger ground motions at larger distances. The aleatory variability in ground motion amplitude was found to depend upon earthquake magnitude and on the degree of nonlinear soil response, For large magnitude earthquakes, the aleatory variability is larger than found by Sadigh et. al. (1997).

Download Full-text

Near-surface frequency-dependent nonlinear damping ratio observation of ground motions using SMART1

Soil Dynamics and Earthquake Engineering ◽

10.1016/j.soildyn.2021.106798 ◽

2021 ◽

Vol 147 ◽

pp. 106798

Author(s):

Chun-Hsiang Kuo ◽

Jyun-Yan Huang ◽

Che-Min Lin ◽

Chun-Te Chen ◽

Kuo-Liang Wen

Keyword(s):

Ground Motions ◽

Damping Ratio ◽

Nonlinear Damping ◽

Frequency Dependent ◽

Near Surface

Download Full-text

A Suite of Alternative Ground-Motion Models (GMMs) for Israel

Bulletin of the Seismological Society of America ◽

10.1785/0120210003 ◽

2021 ◽

Author(s):

Soumya Kanti Maiti ◽

Gony Yagoda-Biran ◽

Ronnie Kamai

Keyword(s):

Seismic Hazard ◽

Ground Motion ◽

Empirical Data ◽

Epistemic Uncertainty ◽

Ground Motions ◽

Plate Boundary ◽

Strong Motion ◽

Engineering Applications ◽

Motion Models ◽

Ground Motion Models

ABSTRACT Models for estimating earthquake ground motions are a key component in seismic hazard analysis. In data-rich regions, these models are mostly empirical, relying on the ever-increasing ground-motion databases. However, in areas in which strong-motion data are scarce, other approaches for ground-motion estimates are sought, including, but not limited to, the use of simulations to replace empirical data. In Israel, despite a clear seismic hazard posed by the active plate boundary on its eastern border, the instrumental record is sparse and poor, leading to the use of global models for hazard estimation in the building code and all other engineering applications. In this study, we develop a suite of alternative ground-motion models for Israel, based on an empirical database from Israel as well as on four data-calibrated synthetic databases. Two host models are used to constrain model behavior, such that the epistemic uncertainty is captured and characterized. Despite the lack of empirical data at large magnitudes and short distances, constraints based on the host models or on the physical grounds provided by simulations ensure these models are appropriate for engineering applications. The models presented herein are cast in terms of the Fourier amplitude spectra, which is a linear, physical representation of ground motions. The models are suitable for shallow crustal earthquakes; they include an estimate of the median and the aleatory variability, and are applicable in the magnitude range of 3–8 and distance range of 1–300 km.

Download Full-text

Testing non-linear amplification factors used in ground motion models

10.5194/egusphere-egu21-4829 ◽

2021 ◽

Author(s):

Karina Loviknes ◽

Danijel Schorlemmer ◽

Fabrice Cotton ◽

Sreeram Reddy Kotha

Keyword(s):

Ground Motion ◽

Site Effects ◽

Ground Motions ◽

Site Amplification ◽

Building Codes ◽

Linear Amplification ◽

Motion Models ◽

Earthquake Predictability ◽

Non Linear ◽

Ground Motion Models

Non-linear site effects are mainly expected for strong ground motions and sites with soft soils and more recent ground-motion models (GMM) have started to include such effects. Observations in this range are, however, sparse, and most non-linear site amplification models are therefore partly or fully based on numerical simulations. We develop a framework for testing of non-linear site amplification models using data from the comprehensive Kiban-Kyoshin network in Japan. The test is reproducible, following the vision of the Collaboratory for the Study of Earthquake Predictability (CSEP), and takes advantage of new large datasets to evaluate whether or not non-linear site effects predicted by site-amplification models are supported by empirical data. The site amplification models are tested using residuals between the observations and predictions from a GMM based only on magnitude and distance. When the GMM is derived without any site term, the site-specific variability extracted from the residuals is expected to capture the site response of a site. The non-linear site amplification models are tested against a linear amplification model on individual well-recording stations. Finally, the result is compared to building codes where non-linearity is included. The test shows that for most of the sites selected as having sufficient records, the non-linear site-amplification models do not score better than the linear amplification model. This suggests that including non-linear site amplification in GMMs and building codes may not yet be justified, at least not in the range of ground motions considered in the test (peak ground acceleration < 0.2 g).

Download Full-text