scholarly journals An analysis of strong-motion accelerometer data from the San Francisco earthquake of March 22, 1957

1958 ◽  
Vol 48 (3) ◽  
pp. 253-268
Author(s):  
D. E. Hudson ◽  
G. W. Housner
Keyword(s):  
San Francisco ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Motion ◽  
Geodetic Survey ◽  
Accelerometer Data ◽  
Structural Dynamic ◽  
Local Geology ◽  
The Relationship ◽  
Area Response

Abstract The San Francisco earthquake of March 22, 1957, was recorded simultaneously by accelerometers at five United States Coast and Geodetic Survey stations in the San Francisco area. Response spectrum curves were computed from the acceleration-time records, and from these response spectrum curves the spectrum intensities have been determined. From these spectrum intensities certain conclusions are drawn as to: (1) the effects of local geology on the recorded ground motions; (2) the calculation of total energy released by the earthquake from strong-motion accelerometer records; (3) possible influence of structural dynamic behavior on the accelerations recorded in building basements, and the relationship between basement accelerations and ground accelerations; and (4) the applicability of a simplified type of strong-motion earthquake instrument for investigations of local distribution effects. A general comparison is made between the present earthquake and typical Pacific Coast earthquakes.

Preliminary Study of the Unsteady Response Spectrum Based on Time-Varying

2011 ◽  
Vol 346 ◽  
pp. 58-62
Author(s):  
Pei Qiang ◽  
Ping Guan ◽  
Jing Tian ◽  
Er Liang Chen
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Strong Motion ◽  
Maximum Response ◽  
Time Varying ◽  
Structural Failure ◽  
Time Duration ◽  
Structure Response ◽  
Preliminary Study ◽  
The Relationship

Engineering characteristics of ground motion can be defined by three factors that are respectively amplitude, frequency and duration. Any one of them in isolation are not fully made known for the ground notions affecting on the structure. Response spectrum theory is one of the principal methods in seismic analysis. The maximum response of structure under earthquake input is only varying with period in traditional response spectrum during the whole time duration. The relationship between the maximum response and duration can not be shown in the response spectrum of earthquake. The concept of unsteady response spectrum is based on moveable spectrum in this paper. Based on the conventional response spectrum, the factor of time is taken into account in unsteady response spectrum research. Then the response spectrum can be studied according to time varying. As examples for strong motion records obtained from WenChuan earthquake, two methods are proposed to research the effect of duration on response spectrum. The result of unsteady response spectrum can play an important role in the further study of the structural failure mechanism and cumulative damage under earthquake loadings.

Bi-Directional Pseudo-Acceleration Response Spectra

2016 ◽  
Vol 10 (04) ◽  
pp. 1650007
Author(s):  
Anat Ruangrassamee ◽  
Chitti Palasri ◽  
Panitan Lukkunaprasit
Keyword(s):  
Seismic Design ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Motion ◽  
Response Spectra ◽  
Acceleration Response ◽  
Acceleration Response Spectra ◽  
Acceleration Response Spectrum ◽  
Two Degree Of Freedom ◽  
Ratio Response

In seismic design, excitations are usually considered separately in two perpendicular directions of structures. In fact, the two components of ground motions occur simultaneously. This paper clarifies the effects of bi-directional excitations on structures and proposes the response spectra called “bi-directional pseudo-acceleration response spectra”. A simplified analytical model of a two-degree-of-freedom system was employed. The effect of directivity of ground motions was taken into account by applying strong motion records in all directions. The analytical results were presented in the form of the acceleration ratio response spectrum defined as the bi-directional pseudo-acceleration response spectrum normalized by a pseudo-acceleration response spectrum.

scholarly journals Estimation of strong ground motions in Mexico City expected for large earthquakes in the Guerrero seismic gap

1993 ◽  
Vol 83 (3) ◽  
pp. 811-829 ◽  
Author(s):  
Hiroo Kanamori ◽  
Paul C. Jennings ◽  
Shri Krishna Singh ◽  
Luciana Astiz
Keyword(s):  
Ground Motion ◽  
Mexico City ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Motion ◽  
Response Spectra ◽  
Simulation Method ◽  
Propagation Path ◽  
Seismic Gap ◽  
Large Earthquakes

Abstract We performed simulations of ground motions in Mexico City expected for large earthquakes in the Guerrero seismic gap in Mexico. The simulation method uses as empirical Green's functions the accelerograms recorded in Mexico City during four small to moderate earthquakes (8 Feb. 1988, Ms = 5.8; 25 April 1989, Mw = 6.9; 11 May 1990, Mw = 5.5; and 31 May 1990, Mw = 6.0) in the Guerrero gap. Because these events occurred in the Guerrero gap, and have typical thrust mechanisms, the propagation path and site effects can be accurately included in our simulation. Fault rupture patterns derived from the 1985 Michoacan earthquake and source scaling relations appropriate for Mexican subduction zone earthquakes are used. If the Guerrero event is similar to the 1985 Michoacan event, the resulting response spectrum in Mexico City will be approximately twice as large as that of the 1985 Michoacan earthquake at periods longer than 2 sec. At periods shorter than 2 sec, the amplitude will be 2 to 3 times larger than that for the Michoacan earthquake. If the events in the Guerrero seismic gap occur as a sequence of magnitude 7.5 to 7.8 events, as they did in the previous sequence around the turn of the century, the strong motion in Mexico City is estimated to be about half that experienced during the 1985 Michoacan earthquake at periods longer than 2 sec. However, several factors affect this estimate. The magnitude of the possible events has a significant range and, if a rupture sequence is such that it enhances ground-motion amplitude with constructive interference, as occurred during the second half of the Michoacan sequence, some components of the ground motion could be amplified by a factor of 2 to 3. To aid in the interpretation of the simulated motion for purposes of design or hazard assessment, design spectra for the CDAO site in Mexico City are derived from the response spectra of the simulated ground motions.

scholarly journals Frequency-dependent site factors for the Icelandic strong-motion array from a Bayesian hierarchical model of the spatial distribution of spectral accelerations

2021 ◽  
pp. 875529302110369
Author(s):  
Sahar Rahpeyma ◽  
Benedikt Halldorsson ◽  
Birgir Hrafnkelsson ◽  
Sigurjón Jónsson
Keyword(s):  
Ground Motion ◽  
Hierarchical Model ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Motion ◽  
Bayesian Hierarchical Model ◽  
Site Factors ◽  
Ground Acceleration ◽  
Small Aperture ◽  
Bayesian Hierarchical

The earthquake ground motions of over 1700 earthquakes recorded on a small-aperture strong-motion array in south Iceland (ICEARRAY I) that is situated on a relatively uniform site condition characterized as rock, exhibit a statistically significant spatial variation of ground-motion amplitudes across the array. Both earthquake and microseismic horizontal-to-vertical spectral ratios (HVSR) have been shown to exhibit distinct and in some cases, bimodal peaks in amplification, indicating site resonance at periods of 0.1–0.3 s, a phenomenon that has been attributed to a surface layer of lava rock lying above a sedimentary layer, a structure that is then repeated with depth under the array. In this study, we implement a Bayesian hierarchical model (BHM) of the seismic ground motions that partitions the model residuals into earthquake event term, station term, and event–station term. We analyzed and compared peak ground acceleration (PGA) with the 5% damped pseudo-acceleration response spectrum (PSA) at oscillator periods of T = 0.05–1.0 s. The results show that the event terms, dominate the total variability of the ground-motion amplitudes over the array. However, the station terms are shown to increase in the period range of 0.1–0.3 s on most stations and to different extents, leading to an increase in the overall variability of ground motions at those periods, captured by a larger inter-station standard deviation. As the station terms are a measure of how much the ground motions at those stations deviate from the array average, they act as proxies for localized site effects and amplification factors. These results, improve our understanding of the key factors that affect the variation of seismic ground motions across the relatively small area of ICEARRAY I. This approach can help to improve the accuracy of earthquake hazard assessments on local scales, which in turn could contribute to more refined seismic risk assessments and engineering decision-making.

scholarly journals Identification of Far-Field Long-Period Ground Motions Using Phase Derivatives

2019 ◽  
Vol 2019 ◽  
pp. 1-20
Author(s):  
Minghui Dai ◽  
Yingmin Li ◽  
Shuoyu Liu ◽  
Yinfeng Dong
Keyword(s):  
Response Spectrum ◽  
Ground Motions ◽  
Strong Motion ◽  
Sedimentary Basins ◽  
Corner Frequency ◽  
Training Dataset ◽  
Far Field ◽  
Long Period ◽  
Velocity Waveform ◽  
Attenuation Models

The characteristics of long-period ground motions are of significant concern to engineering communities largely due to resonance-induced responses of long-period structures to far-field long-period ground motions which are excited by the existence of distant sedimentary basins. Classifications of records enable applications of far-field long-period ground motions in seismology and engineering practices, such as attenuation models and dynamic analysis of structures. Accordingly, the study herein aims to develop an approach for identifying the far-field long-period ground motions in terms of the later-arriving long-period surface waves. Envelope delays derived from phase derivatives are employed to determine the later-arriving long-period components on the basis of phase dispersion. A quantitative calibration for long-period properties is defined in terms of the ratio of energy from later-arriving long-period components to the total energy of a ground motion. In order to increase the accuracy of candidate far-field long-period records caused by sediments, recording stations within basins or plains are collected from the K-NET and KiK-net strong-motion networks. Subsequently, the motions are manually classified into two categories in order to form a training dataset by visual examinations on their velocity waveform. The two predictive variables, including the corner frequency obtained from envelope delays and the corresponding energy ratio, are used for the establishment of the classification criterion. Furthermore, the analysis of classification results provides insight into the causes for discrepancy and verifies the effectiveness of the proposed method. Finally, comparisons of the mean normalized acceleration response spectrum with respect to the predictors, as well as the local site effects, are performed.

An Empirical Relationship between Fourier and Response Spectra Using Spectrum-Compatible Times Series

2017 ◽  
Vol 33 (1) ◽  
pp. 179-199 ◽  
Author(s):  
Luis A. Montejo ◽  
Aidcer L. Vidot-Vega
Keyword(s):  
Time Series ◽  
Earthquake Engineering ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Dependence ◽  
Empirical Relationship ◽  
Amplitude Spectrum ◽  
Strong Motion ◽  
Response Spectra ◽  
Elastic Response

The Fourier amplitude spectrum (FAS) is widely used in seismology and earthquake engineering as it provides valuable information regarding frequency dependent amplitude of the ground motion. However, for structural design and assessment, the preferred representation of seismic hazard continues to be based on the elastic response spectrum. Therefore, conversions between these spectra are often required. In this article, the connection between FAS and the 5% damping pseudo-acceleration response spectrum (5% PSA) is explored using large data sets of spectrum-compatible time series generated from white noise. The strong dependence of the relation between FAS and 5% PSA with strong motion duration is evidenced and a duration dependent empirical relationship between the both spectra is developed. The equation is validated using recorded ground motions and spectrum-compatible time series generated from the modification of these ground motions. The equation allows simpler one-step conversions when compared to iterative approaches based on RVT theory or time-consuming methodologies that require the generation of spectrum-compatible time series.

scholarly journals A simplified instrument for recording strong motion earthquakes

1961 ◽  
Vol 51 (2) ◽  
pp. 159-174
Author(s):  
W. K. Cloud ◽  
D. E. Hudson
Keyword(s):  
Direct Measurement ◽  
Spectrum Analysis ◽  
Response Spectrum ◽  
Strong Motion ◽  
Geodetic Survey ◽  
Initial Cost ◽  
Large Numbers ◽  
Standard Spectrum ◽  
Geological Conditions ◽  
Spectrum Curve

Abstract A strong-motion earthquake recorder for the direct measurement of one point on the response spectrum curve is described, and results obtained with the instrument under field conditions are compared with those obtained by a standard spectrum analysis of accelerograph records. The device has the advantages of low initial cost and of low maintenance expense, and can thus be installed in relatively large numbers. A network of such instruments located at points having various local geological conditions is proposed as a supplement to the U. S. Coast and Geodetic Survey strong-motion seismograph system.

Ground-motion model for subduction earthquakes in northern South America

2021 ◽  
pp. 875529302110275
Author(s):  
Carlos A Arteta ◽  
Cesar A Pajaro ◽  
Vicente Mercado ◽  
Julián Montejo ◽  
Mónica Arcila ◽  
...  
Keyword(s):  
South America ◽  
Ground Motion ◽  
Ground Motions ◽  
Strong Motion ◽  
Motion Prediction ◽  
Depth Range ◽  
Ground Motion Prediction ◽  
Natural Period ◽  
Nazca Plate ◽  
Northern South America

Subduction ground motions in northern South America are about a factor of 2 smaller than the ground motions for similar events in other regions. Nevertheless, historical and recent large-interface and intermediate-depth slab earthquakes of moment magnitudes Mw = 7.8 (Ecuador, 2016) and 7.2 (Colombia, 2012) evidenced the vast potential damage that vulnerable populations close to earthquake epicenters could experience. This article proposes a new empirical ground-motion prediction model for subduction events in northern South America, a regionalization of the global AG2020 ground-motion prediction equations. An updated ground-motion database curated by the Colombian Geological Survey is employed. It comprises recordings from earthquakes associated with the subduction of the Nazca plate gathered by the National Strong Motion Network in Colombia and by the Institute of Geophysics at Escuela Politécnica Nacional in Ecuador. The regional terms of our model are estimated with 539 records from 60 subduction events in Colombia and Ecuador with epicenters in the range of −0.6° to 7.6°N and 75.5° to 79.6°W, with Mw≥4.5, hypocentral depth range of 4 ≤  Zhypo ≤ 210 km, for distances up to 350 km. The model includes forearc and backarc terms to account for larger attenuation at backarc sites for slab events and site categorization based on natural period. The proposed model corrects the median AG2020 global model to better account for the larger attenuation of local ground motions and includes a partially non-ergodic variance model.

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