Repeatability of microseism measurements in Port Hueneme case study

1996 ◽  
Vol 86 (2) ◽  
pp. 428-435
Author(s):  
John M. Ferritto
Keyword(s):  
Ground Motion ◽  
Reference Site ◽  
Reference Sites ◽  
Ground Motion Amplification ◽  
Array Measurements ◽  
Contour Plots ◽  
Soil Site ◽  
A Site

Abstract Microseism measurements can assist in prediction of ground-motion amplification and microzonation. A series of array measurements were conducted in the Port Hueneme, California, area. The measurements were repeated, and the error of microseism measurements is discussed. From the seven individual trials, it was possible to show the convergence of microseism measurements and their repeatability. The series of array measurements of microseisms used both a soil and a rock reference site. The soil site was a site having a well-defined boring log. A comparison is made between results obtained using a rock and a soil reference site. It was found that qualitatively the general dimensionless shape of relative amplification contour plots was similar using both reference sites. Both reference sites showed the same regions as having higher amplification compared with other lower regions.

What is a reference site?

1996 ◽  
Vol 86 (6) ◽  
pp. 1733-1748 ◽  
Author(s):  
Jamison H. Steidl ◽  
Alexei G. Tumarkin ◽  
Ralph J. Archuleta
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Reference Site ◽  
Site Response ◽  
Ground Motions ◽  
Destructive Interference ◽  
Surface Rock ◽  
Reference Motion ◽  
Rock Site ◽  
A Site

Abstract Many methods for estimating site response compare ground motions at sites of interest to a nearby rock site that is considered a “reference” motion. The critical assumption in these methods is that the surface-rock-site record (reference) is equivalent to the input motion at the base of the soil layers. Data collected in this study show that surface-rock sites can have a site response of their own, which could lead to an underestimation of the seismic hazard when these sites are used as reference sites. Data were collected from local and regional earthquakes on digital recorders, both at the surface and in boreholes, at two rock sites and one basin site in the San Jacinto mountains, southern California. The two rock sites, Keenwild and Piñon Flat, are located on granitic bedrock of the southern California peninsular ranges batholith. The basin site, Garner Valley, is an ancestral lake bed with watersaturated sediments, on top of a section of decomposed granite, which overlies the competent bedrock. Ground motion is recorded simultaneously at the surface and in the bedrock at all three sites. When the surface-rock sites are used as the reference site, i.e., the surface-rock motion is used as the input to the basin, the computed amplification underestimates the actual amplification at the basin site for frequencies above 2 to 5 Hz. This underestimation, by a factor of 2 to 4 depending on frequency and site, results from the rock sites having a site response of their own above the 2-to 5-Hz frequencies. The near-surface weathering and cracking of the bedrock affects the recorded ground motions at frequencies of engineering interest, even at sites that appear to be located on competent crystalline rock. The bedrock borehole ground motion can be used as the reference motion, but the effect of the downgoing wave field and the resulting destructive interference must be considered. This destructive interference may produce pseudo-resonances in the spectral amplification estimates. If one is careful, the bedrock borehole ground motion can be considered a good reference site for seismic hazard analysis even at distances as large as 20 km from the soil site.

scholarly journals Summary of Research on Site Response Analysis

2021 ◽  
Vol 276 ◽  
pp. 02024
Author(s):  
Jing Cai ◽  
Jianqi Lu ◽  
Shanyou Li
Keyword(s):  
Ground Motion ◽  
Site Effects ◽  
Reference Site ◽  
Site Response ◽  
Response Analysis ◽  
Observation Data ◽  
Empirical Methods ◽  
Theoretical Methods ◽  
Advantages And Disadvantages ◽  
Soil Site

A large number of seismic observation data and macroscopic survey of earthquake damage indicate that soil site may amplify the intensity of ground-motion and thus aggravate the damage to the structures on the soil site[1]. The influence of site response on ground motion is one of the most important topics in earthquake engineering. The methods of predicting the site effects can be divided into two groups with respect to theoretical methods and empirical methods. The theoretical methods of predicting site effects are to analyse the site response to ground motion based on the theory of seismic wave propagation in which the detailed soil information is required. Whereas the empirical methods predicting the site effects by empirical prediction model which is determined using observed seismic data or ground pulsation data. According to whether the reference site is introduced, the empirical methods can be further divided into the reference site method and the non-reference site method. This article introduces in detail the principles, advantages and disadvantages of various methods of analysing site effects, which is of reference value for further research on site ground motion response.

CONTEXTUALIZING PALIMPSEST OF COLLECTIVE MEMORY IN AN URBAN HERITAGE SITE: Case Study of Chahar Bagh, Shiraz - Iran

2015 ◽  
Vol 9 (1) ◽  
pp. 218 ◽  
Author(s):  
Leila Mahmoudi Farahani ◽  
Marzieh Setayesh ◽  
Leila Shokrollahi
Keyword(s):  
Collective Memory ◽  
Active Part ◽  
Collective Memories ◽  
Cultural Life ◽  
Urban Heritage ◽  
Heritage Site ◽  
Historical Sites ◽  
A Site ◽  
Historical Centre

A landscape or site, which has been inhabited for long, consists of layers of history. This history is sometimes reserved in forms of small physical remnants, monuments, memorials, names or collective memories of destruction and reconstruction. In this sense, a site/landscape can be presumed as what Derrida refers to as a “palimpsest”. A palimpsest whose character is identified in a duality between the existing layers of meaning accumulated through time, and the act of erasing them to make room for the new to appear. In this study, the spatial collective memory of the Chahar Bagh site which is located in the historical centre of Shiraz will be investigated as a contextualized palimpsest, with various projects adjacent one another; each conceptualized and constructed within various historical settings; while the site as a heritage is still an active part of the city’s cultural life. Through analysing the different layers of meaning corresponding to these adjacent projects, a number of principals for reading the complexities of similar historical sites can be driven.

Nonlinear ground-motion amplification by sediments during the 1994 Northridge earthquake

Nature ◽  
10.1038/37586 ◽  
1997 ◽  
Vol 390 (6660) ◽  
pp. 599-602 ◽  
Author(s):  
Edward H. Field ◽  
Paul A. Johnson ◽  
Igor A. Beresnev ◽  
Yuehua Zeng
Keyword(s):  
Ground Motion ◽  
Northridge Earthquake ◽  
Ground Motion Amplification ◽  
1994 Northridge Earthquake

An Example to Us All: Child Development and Identity Construction in Early 20th-Century Playgrounds

10.1068/a3237 ◽  
2000 ◽  
Vol 32 (4) ◽  
pp. 599-616 ◽  
Author(s):  
Elizabeth A Gagen
Keyword(s):  
Child Development ◽  
Public Space ◽  
20Th Century ◽  
The United States ◽  
Development Theory ◽  
Gender Identities ◽  
Construction Of Identity ◽  
A Site ◽  
Us Cities

At the turn of the 20th century, children's play came under new and heightened scrutiny by urban reformers. As conditions in US cities threatened traditional notions of order, reformers sought new ways to direct urban-social development. In this paper I explore playground reform as an institutional response that aimed to produce and promote ideal gender identities in children. Supervised summer playgrounds were established across the United States as a means of drawing children off the street and into a corrective environment. Drawing from literature published by the Playground Association of America and a case study of playground management in Cambridge, MA, I explore playground training as a means of constructing gender identities in and through public space. Playground reformers asserted, drawing from child development theory, that the child's body was a conduit through which ‘inner’ identity surfaced. The child's body became a site through which gender identities could be both monitored and produced, compelling reformers to locate playgrounds in public, visible settings. Reformers' conviction that exposing girls to public vision threatened their development motivated a series of spatial restrictions. Whereas boys were unambiguously displayed to public audiences, girls' playgrounds were organised to accommodate this fear. Playground reformers' shrewd spatial tactics exemplify the ways in which institutional authorities conceive of and deploy space toward the construction of identity.

Sign in / Sign up

Export Citation Format

Share Document