Analysis of Site Amplification Phenomena: An Application in Ripabottoni for the 2002 Molise, Italy, Earthquake

2004 ◽  
Vol 20 (1_suppl) ◽  
pp. 107-118 ◽  
Author(s):  
Marco Massa ◽  
Gabriele Ferretti ◽  
Andrea Cevasco ◽  
Luana Isella ◽  
Claudio Eva
Keyword(s):  
Fundamental Frequency ◽  
Site Effects ◽  
Site Response ◽  
Site Amplification ◽  
Simulation Code ◽  
Dimensional Simulation ◽  
Molise Region ◽  
A Site ◽  
The University ◽  
The Village

The geophysical working group of the University of Genoa conducted a field experiment to analyze site amplification effects in Ripabottoni, a village in the Molise region of Italy. We used both noise and earthquake recordings, combined with detailed geologic and geotechnical surveys, to define site amplification phenomena. The site effects determination was obtained using the Nakamura technique and the H/V spectral analysis applied to earthquake recordings. The results were validated by applying a one-dimensional simulation code. The computed spectral ratios point out three different typologies of site effects: the southern sector of Ripabottoni is characterized by an absence of local amplification phenomena; the central sector of the village shows a local amplification phenomena with a fundamental frequency of 4–6 Hz; and the northeastern side of the village shows a site response at a fundamental frequency between 2–3 Hz.

Site Effects of the 2003 Bam, Iran, Earthquake

2005 ◽  
Vol 21 (1_suppl) ◽  
pp. 125-136 ◽  
Author(s):  
Mohammad Kazem Jafari ◽  
Mohammad Reza Ghayamghamian ◽  
Mohammad Davoodi ◽  
Mohsen Kamalian ◽  
Abdollah Sohrabi-Bidar
Keyword(s):  
High Frequency ◽  
Site Effects ◽  
Site Effect ◽  
Site Amplification ◽  
Frequency Characteristics ◽  
Ground Conditions ◽  
A Site ◽  
The City

The site amplification characteristics of the 2003 Bam, Iran, earthquake were investigated based on geological studies as well as geophysical, microtremor and aftershock measurements conducted by IIEES in the study area. A site effect microzonation map was prepared classifying the ground conditions of the city into five distinct categories, based on their stiffness, thickness, and frequency characteristics. The highest percentage of damage was concentrated in sites with stiff shallow and medium depth soils, which possessed considerable amplification potentials in high frequency ranges.

A model for estimating amplification effects on seismic hazards and scenario ground motions in southern Ontario

2017 ◽  
Vol 44 (6) ◽  
pp. 441-451 ◽  
Author(s):  
Sebastian Braganza ◽  
Gail M. Atkinson
Keyword(s):  
Site Response ◽  
Ground Motions ◽  
Peak Frequency ◽  
Site Amplification ◽  
Seismic Hazards ◽  
Damage Potential ◽  
Southern Ontario ◽  
Response Variable ◽  
Study Support ◽  
A Site

Site amplification effects in southern Ontario are highly variable and strongly influence felt effects and damage potential. Site parameters such as shear-wave velocity in the top 30 metres of soil (VS30), traditionally used to estimate site amplification, are not well known in this region. Thus, regional maps of shaking potential and seismic hazard are often overgeneralized. In this study, a site amplification model based on peak frequency (fpeak) is compared to one based on VS30, as given by the 2015 National Building Code of Canada (NBCC). Earthquakes and scenario events are used to estimate ground motions and shaking intensities. It is shown that both models generally predict similar felt intensities but show significant differences in their predicted amplification of ground motions as a function of frequency. The results of this study support the use of fpeak as a site response variable for estimating amplification effects in southern Ontario.

Modeling of Empirical Transfer Functions with 3D Velocity Structure

2021 ◽  
Author(s):  
Zhifeng Hu ◽  
Daniel Roten ◽  
Kim B. Olsen ◽  
Steven M. Day
Keyword(s):  
Material Properties ◽  
Site Effects ◽  
Velocity Structure ◽  
Transfer Functions ◽  
Site Response ◽  
Hazard Analysis ◽  
Earthquake Hazard ◽  
Site Effect ◽  
3D Models ◽  
Site Amplification

ABSTRACT Empirical transfer functions (ETFs) between seismic records observed at the surface and depth represent a powerful tool to estimate site effects for earthquake hazard analysis. However, conventional modeling of site amplification, with assumptions of horizontally polarized shear waves propagating vertically through 1D layered homogeneous media, often poorly predicts the ETFs, particularly, in which large lateral variations of velocity are present. Here, we test whether more accurate site effects can be obtained from theoretical transfer functions (TTFs) extracted from physics-based simulations that naturally incorporate the complex material properties. We select two well-documented downhole sites (the KiK-net site TKCH05 in Japan and the Garner Valley site, Garner Valley Downhole Array, in southern California) for our study. The 3D subsurface geometry at the two sites is estimated by means of the surface topography near the sites and information from the shear-wave profiles obtained from borehole logs. By comparing the TTFs to ETFs at the selected sites, we show how simulations using the calibrated 3D models can significantly improve site amplification estimates as compared to 1D model predictions. The primary reason for this improvement in 3D models is redirection of scattering from vertically propagating to more realistic obliquely propagating waves, which alleviates artificial amplification at nodes in the vertical-incidence response of corresponding 1D approximations, resulting in improvement of site effect estimation. The results demonstrate the importance of reliable calibration of subsurface structure and material properties in site response studies.

Two-stage nonlinear site amplification modeling for Japan with VS30 and fundamental frequency dependency

2020 ◽  
Vol 36 (3) ◽  
pp. 1359-1385
Author(s):  
Dong Youp Kwak ◽  
Emel Seyhan
Keyword(s):  
Fundamental Frequency ◽  
Site Effects ◽  
Functional Form ◽  
Site Amplification ◽  
Sediment Depth ◽  
Two Stage ◽  
Second Stage ◽  
Long Period ◽  
Site Term ◽  
Two Stages

We describe a two-stage nonlinear site amplification model that considers both the sediment depth and the fundamental frequency of the soil. Adopting a non-reference site approach, empirical site amplification ratios for 1591 Kyoshin and Kiban Kyoshin network sites are developed. This process involves analyzing 92,025 surface ground motion recordings from 305 earthquakes between 1997 and 2012. The model is developed in two stages: first, we regress the total empirical site effects in terms of VS30; second, we fit a functional form to the residuals from the first stage using the fundamental period of the site. We validate the model through residual analyses and statistical methods. This study shows that the peak soil period increases with the equivalent shear strain ( Iγ), while the peak amplitude decreases with Iγ. The first-stage site term reduces the error at mid-to-long period ranges (>0.1 s) by 0.11 from the error of the initial site term without any constraints. The second-stage site term reduces the error further as 0.06. Finally, we discuss the model limitations and the applicability range of the predictor variables.

scholarly journals Selection of an Appropriate Bedrock for Site Amplification Studies.

2021 ◽  
Author(s):  
Bhavesh Pandey ◽  
Ravi S Jakka
Keyword(s):  
Shear Wave ◽  
Half Space ◽  
Fundamental Frequency ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Reference Site ◽  
Strong Motion ◽  
Site Amplification ◽  
A Site ◽  
Selection Of

Abstract The selection of half-space or reference sites significantly influences site amplification studies. However, there are no well-defined guidelines in the literature. Generally, a layer with a local shear wave velocity (VS) of more than 760 m/s is considered a bedrock/half-space/reference site. This study attempts to formulate a rationale for selecting bedrock stiffness to be used as a half-space/reference site. For this study, VS,30 (average shear wave velocity of top 30-meter soil strata from shear wave velocity measurements) and the site's fundamental frequency (obtained from Horizontal to vertical spectral ratio of ambient vibration records) were used as proxies to study the influence of bedrock/half-space and development of a rationale for their selection. This study uses strong-motion data from India's sixty-two strong motion stations and a few from Japan (Kik-Net). The results suggest that considering a site with a shear wave velocity of 760 m/s may not be suitable as a half-space/bedrock for most geomorphological conditions. The results also recognize a pattern that can help in the development of a mathematical model for determining the bedrock for a site using VS,30 and its fundamental frequency as a proxy.

Edgar Johnson Allen 1866-1942

1943 ◽  
Vol 4 (12) ◽  
pp. 357-367 ◽  
Keyword(s):  
Major Part ◽  
Natural Philosophy ◽  
Working Life ◽  
Great Success ◽  
The Third ◽  
Marine Biological Association ◽  
A Site ◽  
The University ◽  
The Village ◽  
The City

The name of E. J. Allen will always be associated with the Marine Biological Association and its Laboratory at Plymouth. It was to this institution that he devoted almost the whole of his working life, and it was under his wise guidance that it grew from small beginnings, through long years of anxiety and disappointment, to the established position it ultimately attained. He was the second son of the Rev. Richard Allen of Liverpool, and he was born at Preston in Lancashire on 6 April 1866. His father had been ordained as a Wesleyan Methodist minister in 1859 and it was while serving at Bideford in Devon that he met and married Emma Johnson, the daughter of a shipbuilder of that town who was descended from a freeman of Exeter, long connected with ships and shipping. There were eight children of this marriage, five sons and three daughters. The sons were all educated at John Wesley’s school, originally founded in 1748 at the village of Kingswood, near Bristol, and transferred in 1851 to a site on Lansdown Hill, overlooking the city of Bath. The eldest son, Dr H. N. Allen, was Professor of Engineering and afterwards Principal of the College of Science at Poona; the third son, C. B. Allen, became Assistant General Manager of the Midland Bank; the fourth, E. L. Allen, was Headmaster of the School of Art at Redditch; and the youngest, Dr H. S. Allen, F.R.S., is Professor of Natural Philosophy in the University of St Andrews. E. J. Allen was at school at the Grove (near Leeds) and at Kingswood (Bath) from 1876 to 1882, and here he came under the influence of T. G. Osborn, who was headmaster of both schools and achieved great success. It is said that ‘he infused a marked enthusiasm into his upper boys; an extraordinary zeal for work took possession of the major part of them’. At Kingswood during his last two years he had as a contemporary Arthur Willey, who also attained distinction in zoological research.

Learning the anthropology of development: the university as a site of knowledge construction and identity formation

Journal ◽  
2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Tanya Jakimow
Keyword(s):  
Identity Formation ◽  
Lifelong Learning ◽  
Knowledge Construction ◽  
Multiple Identities ◽  
Classroom Teachers ◽  
Practical Skills ◽  
Student Reactions ◽  
A Site ◽  
The University ◽  
Anthropology Of Development

Recent work exploring student reactions to the anthropology of development highlights the importance of going beyond simply imparting practical skills, or alternatively delivering content that offers an unrelenting critique (Djohari 2011; Handler 2013). In this paper, I argue that by casting an anthropological eye on the classroom, teachers can provide a learning environment in which students transform into reflective ‘novice’ practitioners equipped for lifelong learning. This involves making explicit the processes of knowledge construction in the classroom, and by extension, the development field. It entails providing the resources through which students can become social beings in the development sector, with attention to expanding the possibilities for the formation of multiple identities. 

Simulation-based site amplification model for shallow bedrock sites in Korea

2021 ◽  
pp. 875529302098198
Author(s):  
Muhammad Aaqib ◽  
Duhee Park ◽  
Muhammad Bilal Adeel ◽  
Youssef M A Hashash ◽  
Okan Ilhan
Keyword(s):  
Linear Models ◽  
Site Response ◽  
Site Amplification ◽  
One Dimensional ◽  
Nonlinear Component ◽  
Nonlinear Site Response ◽  
Simulation Based ◽  
Linear And Nonlinear ◽  
Input Motion ◽  
Nonlinear Components

A new simulation-based site amplification model for shallow sites with thickness less than 30 m in Korea is developed. The site amplification model consists of linear and nonlinear components that are developed from one-dimensional linear and nonlinear site response analyses. A suite of measured shear wave velocity profiles is used to develop corresponding randomized profiles. A VS30 scaled linear amplification model and a model dependent on both VS30 and site period are developed. The proposed linear models compare well with the amplification equations developed for the western United States (WUS) at short periods but show a distinct curved bump between 0.1 and 0.5 s that corresponds to the range of site natural periods of shallow sites. The response at periods longer than 0.5 s is demonstrated to be lower than those of the WUS models. The functional form widely used in both WUS and central and eastern North America (CENA), for the nonlinear component of the site amplification model, is employed in this study. The slope of the proposed nonlinear component with respect to the input motion intensity is demonstrated to be higher than those of both the WUS and CENA models, particularly for soft sites with VS30 < 300 m/s and at periods shorter than 0.2 s. The nonlinear component deviates from the models for generic sites even at low ground motion intensities. The comparisons highlight the uniqueness of the amplification characteristics of shallow sites that a generic site amplification model is unable to capture.

The 1805 Forékariah Conference: A Case of Political Intrigue, Economic Advantage, Network Building

1998 ◽  
Vol 25 ◽  
pp. 219-262 ◽  
Author(s):  
Bruce L. Mouser
Keyword(s):  
Sierra Leone ◽  
Economic Advantage ◽  
University Of Illinois ◽  
University Library ◽  
Network Building ◽  
The University ◽  
The Village

Palavers, great meetings, grand conferences, “tribal” meetings— these are terms used to describe meetings among peoples in and near Sierra Leone, meetings in which political, diplomatic, and economic questions are discussed and sometimes resolved at the village, intervillage, and occasionally, national levels. These conferences vary in size and importance, depending on dimensions of conflicts or questions to be resolved. This paper focuses on one such conference that convened at Forékariah, the capital of Moria, in 1805 and on circumstances leading to it. It is based largely upon a lengthy first-hand report deposited at the University Library, University of Illinois at Chicago. This paper is presented in two parts: a description of the conference and its placement in Sierra Leone and Morian histories, and the text of the report produced by Sierra Leone observers.From the earliest records of British officials at Sierra Leone, there are citations to specific “indigenous” meetings and allusions to others that supposedly occurred (indeed they would have had to occur for certain events to follow). One of the earliest large conferences described in detail in these records is one that convened at Forékariah from 24 March to 6 April 1805. The extant contemporary written record of this conference was produced by Alexander Smith, the Sierra Leone Company's and Governor William Day's principal representative at the conference. Other observers from Freetown included William Francis, Andrew Moore, Captain Smith, and Charles Shaw. Alexander Smith did not identify a specific interpreter nor describe what method he used to record the detailed arguments presented by participants. Certainly the filter of language and inter pretation must have influenced the record's content. If one places the conference within the framework of Company and Sierra Leone history, however, and accepts the premise that the Freetown observers were relatively unbiased since they were not principal parties to the palavers resolved, the report can be seen as one of a very few in which Sierra Leone's officials presented themselves in such uninvolved fashion.

Estimation of Site Amplification from Geotechnical Array Data Using Neural Networks

2021 ◽  
Author(s):  
Daniel Roten ◽  
Kim B. Olsen
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Site Response ◽  
Site Amplification ◽  
Data Driven ◽  
Vertical Array ◽  
The Neural Network ◽  
Simplifying Assumptions ◽  
The Mean ◽  
Fully Connected

ABSTRACT We use deep learning to predict surface-to-borehole Fourier amplification functions (AFs) from discretized shear-wave velocity profiles. Specifically, we train a fully connected neural network and a convolutional neural network using mean AFs observed at ∼600 KiK-net vertical array sites. Compared with predictions based on theoretical SH 1D amplifications, the neural network (NN) results in up to 50% reduction of the mean squared log error between predictions and observations at sites not used for training. In the future, NNs may lead to a purely data-driven prediction of site response that is independent of proxies or simplifying assumptions.

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