Theoretical Synthesis and Analysis of Strong Motion Spectra of Earthquakes

1974 ◽  
Vol 11 (2) ◽  
pp. 278-297 ◽  
Author(s):  
H. S. Hasegawa
Keyword(s):  
Surface Waves ◽  
Ground Motion ◽  
Nuclear Reactor ◽  
Attenuation Factor ◽  
Strong Motion ◽  
Response Spectra ◽  
Acceleration Response ◽  
Response Level ◽  
Motion Signal ◽  
Predicted Values

A comparison of theoretical Fourier amplitude spectra of strong ground motion (FS) with the corresponding spectra of real earthquake accelerograms is useful in elucidating the physical processes that contribute significantly to the ground motion signal. At low freqencies the contribution from surface waves tends to predominate. At intermediate frequencies the joint contributions from the direct shear wave and from complex crustal reverberations are important. At high frequencies the attenuation factor and/or source mechanism effects tend to dominate, depending on type of material and distance traversed.For a specified ground motion spectra and a particular acceleration response level, there are many theoretically predicted smoothed response spectra for velocity and displacement, depending on the particular combination of earthquake magnitude and source-to-receiver distance selected. In contrast the Newmark–Hall method (for nuclear reactor facilities) predicts a single value for the velocity and displacement response level when the acceleration response level is specified; the Newmark–Hall response values for velocity and displacement are somewhat greater than the corresponding maximum theoretically predicted values. Much of this difference is likely due to the fact that, in the theoretical spectra used for comparison purposes, contributions from complex crustal reverberations and from surface waves were not included.

Concurrent Design Forces in Structures under Three-Component Orthotropic Seismic Excitation

2002 ◽  
Vol 18 (1) ◽  
pp. 1-17 ◽  
Author(s):  
K. Anastassiadis ◽  
I. E. Avramidis ◽  
P. Panetsos
Keyword(s):  
Ground Motion ◽  
Design Procedure ◽  
Strong Motion ◽  
Response Spectra ◽  
Concurrent Design ◽  
Motion Model ◽  
Specific Point ◽  
Extreme Stress ◽  
Seismic Motion

According to the model of Penzien and Watabe, the three translational ground motion components on a specific point of the ground are statistically noncorrelated along a well-defined orthogonal system of axes p, w, and v, whose orientation remains reasonably stable over time during the strong motion phase of an earthquake. This orthotropic ground motion is described by three generally independent response spectra Sa, Sb, and Sc, respectively. The paper presents an antiseismic design procedure for structures according to the above seismic motion model. This design includes a) determination of the critical orientation of the seismic input, i.e., the orientation that gives the largest response, b) calculation of the maximum and the minimum values of any response quantity, and c) application of either the Extreme Stress Method or the Extreme Force Method for determining the most unfavorable combinations of several stress resultants (or sectional forces) acting concurrently at a specified section of a structural member.

Engineering observations on ground motion at the Van Norman Complex after the 1994 Northridge earthquake

1996 ◽  
Vol 86 (1B) ◽  
pp. S333-S349 ◽  
Author(s):  
J. P. Bardet ◽  
C. Davis
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Low Frequency ◽  
Strong Motion ◽  
Response Spectra ◽  
Vertical Acceleration ◽  
Northridge Earthquake ◽  
Peak Acceleration ◽  
Geotechnical Earthquake Engineering ◽  
1994 Northridge Earthquake

Abstract During the 1994 Northridge earthquake, the Van Norman Complex yielded an unprecedented number of recordings with high acceleration, in the close proximity of the fault rupture. These strong-motion recordings exhibited the pulses of the main event. One station recorded the largest velocity ever instrumentally recorded (177 cm/sec), resulting from a 0.86 g peak acceleration with a low frequency. Throughout the complex, the horizontal accelerations reached peak values ranging from 0.56 to 1.0 g, except for the complex center, where the peak acceleration did not exceed 0.43 g. The vertical acceleration reached maximum peak values comparable with those of the horizontal acceleration. The acceleration response spectra in the longitudinal and transverse directions were significantly different. Such a difference, which is not yet well documented in the field of geotechnical earthquake engineering, indicates that the amplitude and frequency content of the ground motion was directionally dependent in the Van Norman Complex.

Basin Amplification Effects in the Puget Lowland, Washington, from Strong-Motion Recordings and 3D Simulations

2020 ◽  
Vol 110 (2) ◽  
pp. 534-555 ◽  
Author(s):  
Mika Thompson ◽  
Erin A. Wirth ◽  
Arthur D. Frankel ◽  
J. Renate Hartog ◽  
John E. Vidale
Keyword(s):  
Surface Waves ◽  
Ground Motion ◽  
Puget Sound ◽  
Strong Motion ◽  
Sedimentary Basins ◽  
Amplification Factors ◽  
Megathrust Earthquakes ◽  
Local Earthquakes ◽  
Basin Effects ◽  
Basin Edge

ABSTRACT Sedimentary basins in the Puget Sound region, Washington State, increase ground-motion intensity and duration of shaking during local earthquakes. We analyze Pacific Northwest Seismic Network and U.S. Geological Survey strong-motion recordings of five local earthquakes (M 3.9–6.8), including the 2001 Nisqually earthquake, to characterize sedimentary basin effects within the Seattle and Tacoma basins. We observe basin-edge generated surface waves at sites within the Seattle basin for most ray paths that cross the Seattle fault zone. We also note previously undocumented basin-edge surface waves in the Tacoma basin during one of the local earthquakes. To place quantitative constraints on basin amplification, we determine amplification factors by computing the spectral ratios of inside-basin sites to outside-basin sites at 1, 2, 3, and 5 s periods. Ground shaking is amplified in the Seattle basin for all the earthquakes analyzed and for a subset of events in the Tacoma basin. We find that the largest amplification factors in the Seattle basin are produced by a shallow earthquake located to the southwest of the basin. Our observation suggests that future shallow crustal and megathrust earthquakes rupturing west of the Puget Lowland will produce greater amplification within the Seattle basin than has been seen for intraslab events. We also perform ground-motion simulations using a finite-difference method to validate a 3D Cascadia velocity model (CVM) by comparing properties of observed and synthetic waveforms up to a frequency of 1 Hz. Basin-edge effects are well reproduced in the Seattle basin, but are less well resolved in the Tacoma basin. Continued study of basin effects in the Tacoma basin would improve the CVM.

scholarly journals A Procedure to Select Earthquake Time Histories for Deterministic Seismic Hazard Analysis: Case Studies of Major Cities in Taiwan

2017 ◽  
Author(s):  
Duruo Huang ◽  
Wenqi Du
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Surface ◽  
Strong Motion ◽  
Response Spectra ◽  
Dynamic Responses ◽  
Motion Time ◽  
Acceleration Time Histories ◽  
Time Histories ◽  
Deterministic Seismic Hazard

Abstract. In performance-based seismic design, ground-motion time histories are needed for analyzing dynamic responses of nonlinear structural systems. However, the number of strong-motion data at design level is often limited. In order to analyze seismic performance of structures, ground-motion time histories need to be either selected from recorded strong-motion database, or numerically simulated using stochastic approaches. In this paper, a detailed procedure to select proper acceleration time histories from the Next Generation Attenuation (NGA) database for several cities in Taiwan is presented. Target response spectra are initially determined based on a local ground motion prediction equation under representative deterministic seismic hazard analyses. Then several suites of ground motions are selected for these cities using the Design Ground Motion Library (DGML), a recently proposed interactive ground-motion selection tool. The selected time histories are representatives of the regional seismic hazard, and should be beneficial to earthquake studies when comprehensive seismic hazard assessments and site investigations are yet available. Note that this method is also applicable to site-specific motion selections with the target spectra near the ground surface considering the site effect.

Spatial Variability of Source and Attenuation Characteristics in Large Ground-Motion Datasets

2020 ◽  
Author(s):  
Sreeram Reddy Kotha ◽  
Graeme Weatherill ◽  
Dino Bindi ◽  
Fabrice Cotton
Keyword(s):  
Spatial Variability ◽  
Ground Motion ◽  
Ground Motions ◽  
Low Frequency ◽  
Strong Motion ◽  
Response Spectra ◽  
Large Datasets ◽  
Earthquake Scenarios ◽  
Crustal Earthquakes ◽  
Geographical Regions

<p>Ground-Motion Models (GMMs) characterize the random distributions of ground-motions for a combination of earthquake source, wave travel-path, and the effected site’s geological properties. Typically, GMMs are regressed over a compendium of strong ground-motion recordings collected from several earthquakes recorded at multiple sites scattered across a variety of geographical regions. The necessity of compiling such large datasets is to expand the range of magnitude, distance, and site-types; in order to regress a GMM capable of predicting realistic ground-motions for rare earthquake scenarios, e.g. large magnitudes at short distances from a reference rock site. The European Strong-Motion (ESM) dataset is one such compendium of observations from a few hundred shallow crustal earthquakes recorded at a several hundred seismic stations in Europe and Middle-East.</p><p>We developed new GMMs from the ESM dataset, capable of predicting both the response spectra and Fourier spectra in a broadband of periods and frequencies, respectively. However, given the clear tectonic and geological diversity of the data, possible regional and site-specific differences in observed ground-motions needed to be quantified; whilst also considering the possible contamination of data from outliers. Quantified regional differences indicate that high-frequency ground-motions attenuate faster with distance in Italy compared to the rest of Europe, as well as systematically weaker ground-motions from central Italian earthquakes. In addition, residual analyses evidence anisotropic attenuation of low frequency ground-motions, imitating the pattern of shear-wave energy radiation. With increasing spatial variability of ground-motion data, the GMM prediction variability apparently increases. Hence, robust mixed-effects regressions and residual analyses are employed to relax the ergodic assumption.</p><p>Large datasets, such as the ESM, NGA-West2, and from KiK-Net, provide ample opportunity to identify and evaluate the previously hypothesized event-to-event, region-to-region, and site-to-site differences in ground-motions. With the appropriate statistical methods, these variabilities can be quantified and applied in seismic hazard and risk predictions. We intend to present the new GMMs: their development, performance and applicability, prospective improvements and research needs.</p>

On-site Earthquake Early Warning: Predictive Models for Acceleration Response Spectra Considering Site-Effects

2020 ◽  
Author(s):  
Antonio Giovanni Iaccarino ◽  
Matteo Picozzi ◽  
Dino Bindi ◽  
Daniele Spallarossa
Keyword(s):  
Ground Motion ◽  
Site Effects ◽  
Cross Validation ◽  
Prediction Models ◽  
Random Effect ◽  
Response Spectra ◽  
Site Effect ◽  
Ground Motion Prediction ◽  
Acceleration Response ◽  
Effect Regression

<p>Including site specific amplification factors in ground motion prediction models represented an advance for PSHA (Atkinson 2006; Rodríguez-Marek et al. 2013; Kotha et al. 2017) that has become nowadays a standard. However, this issue has only recently received attention by the seismological community of earthquake early warning (EEW) (Spallarossa et al., 2019; Zhao and Zhao, 2019), which applications require a real-time prediction of ground motion and the delivery of alert messages to users for mitigating their exposure to seismic risk. Indeed, all EEW systems are high-technological infrastructures devoted to the real-time and automatic detection of earthquakes, rapid assessment of the associated seismic hazard for targets and the prompt delivery of alerts trough fast telecommunication networks. Among them, the on-site approaches are based on seismic networks placed near to the target, indifferently by the location of seismic threats and they issue the alert predicting the ground motion at the target from P-wave parameter. This configuration cause that On-Site EEWS are generally highly affected by site conditions.</p><p>In this work, we calibrated ground motion prediction models for on-site EEW considering acceleration response spectra (RSA) and the P-waves EEW parameters Iv2 and Pd, and we investigated the role of site-effects. We considered a dataset of nearly 60 earthquakes belonging to the Central Italy 2016-17 sequence. The high density of stations near to the sequence has allowed us to use a non-ergodic random-effect regression approach to explore and to reduce the contribution of site-effects to the uncertainty of the On-site laws predictions. We grouped the records in two ways: by stations and by EC8 classification. Then, we validated the estimated models by the Leave One Out (L1Out) technique and applied a K-means analysis to assess the performance of the EC8 classification.</p><p>The residuals analysis proved that grouping by station provides a set of relations that improves the predictions at many stations. On the contrary, L1Out cross-validation proved that the regressions retrieved grouping by EC8 classification produce higher uncertainties on the predictions than the others. Furthermore, the cross-validation proved that Iv2 is more correlated to RSA than Pd. Finally, the analysis of the random effect vs period curves confirmed that EC8 classification is unrelated to the site effect on RSA even looking only at the trend of these curves.</p><p>In conclusion, non-ergodic random-effect regression can be used also in the EEW applications to predict site-specific ground motion. EEWS that use this approach are less dependent by site-effect and able to provide more precise and reliable alerts.</p>

Strong motion accelerograph records from the 1993 Napierville earthquake

1995 ◽  
Vol 22 (1) ◽  
pp. 190-196
Author(s):  
René Tinawi ◽  
André Filiatrault ◽  
Pierre Léger
Keyword(s):  
Ground Motion ◽  
Energy Content ◽  
Strong Motion ◽  
Response Spectra ◽  
High Energy ◽  
Period Range ◽  
Attenuation Relationships ◽  
Acceleration Time Histories ◽  
Short Period ◽  
Time Histories

An earthquake of magnitude ML = 4.3 occurred near Napierville, Quebec, on November 16, 1993. An accelerograph at the liquefaction, storage, and regasification plant of Gaz Metropolitain in Montreal, about 55 km from the epicentre, recorded the ground motion. Although the maximum accelerations and velocities from this event are small, the acceleration time histories do confirm the high energy content in the very short period range. The recorded ground motion and corresponding absolute acceleration response spectra are presented and various attenuation relationships, proposed for eastern North America, are utilized to compare the measured and predicted ground motion parameters. Key words: Napierville earthquake, attenuation relationships, acceleration spectra, strong motion records.

scholarly journals Strong motion earthquake records

1974 ◽  
Vol 7 (2) ◽  
pp. 53-61
Author(s):  
P. W. Taylor
Keyword(s):  
Strong Motion ◽  
Response Spectra ◽  
Elementary Level ◽  
Acceleration Response ◽  
Earthquake Intensity ◽  
Earthquake Records ◽  
Earthquake Resistant ◽  
Earthquake Resistant Structures ◽  
San Fernando ◽  
Initial Concept

This article reviews, at an elementary level, the ways in which information from strong-motion earthquake records may be presented. The various methods of presentation are illustrated with reference to the strong-motion records obtained at Pacoima Dam, in the San Fernando earthquake of 1971. As acceleration response spectra from the basis of most codes for the design of earthquake resistant structures, the historical development of response spectra is traced from the initial concept. Simplification of presentation by the use of 'pseudo' response spectra, and the use of spectra to define earthquake intensity are outlined.

Surface-wave dispersion analysis in Mexico City

1995 ◽  
Vol 85 (4) ◽  
pp. 1116-1126
Author(s):  
Francisco J. Chávez-García ◽  
Jaime Ramos-Martínez ◽  
Evangelina Romero-Jiménez
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Ground Motion ◽  
Mexico City ◽  
Rayleigh Waves ◽  
Strong Motion ◽  
Clay Layer ◽  
Period Range ◽  
Wave Trains ◽  
Refraction Data

Abstract In this article, we present an observational investigation of ground motion at Mexico City focused on surface waves. Our purpose is 2-fold; first, to understand incident ground motion during the great Michoacán earthquake of 19 September 1985, and second, to characterize surface waves propagating in the lake-bed zone. To this end we analyze the strong-motion records obtained at Mexico City for the large (MS = 8.1) earthquake of 19 September 1985. It is shown that, in the low-frequency range, we observe the Rayleigh fundamental mode in both the vertical and the radial components, and the Love fundamental mode in the transverse component at all the strong-motion stations. The vertical component also shows the first higher mode of Rayleigh waves. We use a very broadband record obtained at station CU for the smaller (MS = 6.7) earthquake of 14 May 1993 to verify that the dispersion computed from the model of Campillo et al. (1989) represents well the average surface-wave propagation between the coast and Mexico City in the 7- to 10-sec period range. We use this result to assign absolute times to the strong-motion records of the Michoacán event. This allowed us to identify additional wave trains that propagate laterally in directions other than great circle in the 3- to 5-sec period range. These wave trains are identified as Love waves. In a second analysis, we study a set of refraction data obtained during a small-scale (250 m) experiment on the virgin clay of the lake-bed zone. Phase-velocity dispersion curves for several modes of Rayleigh waves are identified in the refraction data and inverted to obtain an S-wave velocity profile. This profile is used as the uppermost layering in a 2D model of Mexico City valley. The results of numerical simulation show that surface waves generated by lateral finiteness of the clay layer suffer large dispersion and attenuation. We conclude that surface waves generated by the lateral heterogeneity of the upper-most stratigraphy very significantly affect ground motion near the edge of the valley, but their importance is negligible for distances larger than 1.5 km from the edge. Thus, locally generated surface waves propagating through the clay layer cannot explain late arrivals observed for the 1985 event. We suggest that the long duration of strong motion is due to the interaction between lateral propagation of waves guided by deep layers (1 to 4 km) and the surficial clay layer. This interaction is possible by the coincidence of the dominant frequency of the uppermost layers and the frequency of the deeply guided waves.

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