Site characterization of strong-motion stations of Himalaya and adjoining plains

Kamal

et al. 2022

Vietnam J. Earth Sci.

Self Cite

Site classification is vital to carry out seismic hazard analysis of a region and get the damage patterns caused by earthquakes. In the present study, the ground motion of earthquakes recorded from 2015 to 2019 at 84 sites of the seismic network array of Earthquake Early Warning System for Uttarakhand are analyzed for site classification purposes. The predominant period from the mean horizontal to vertical spectral ratio curves was estimated. The classification schemes devised by Japan Road Association and National Earthquake Hazards Reduction Program are applied to classify the sites. Along with this, two other site classification indexes schemes are also applied for classification purposes. Data winnowing techniques are used over the ground motion records to pick out desirable quality records. Conclusively, the site class with the highest recurrence rate amongst the used methods is selected as the final class for that particular site. The effect of magnitude, distance and depth on horizontal to vertical spectral ratio are described and concluded that these factors do not significantly affect the ratio curves. The average horizontal to vertical spectral ratio curves obtained for all the sites matches well with the existing literature. The classification of a few sites are verified from the classification done by other methods in recent studies. It is evident from the results that the classification done in this study matches well with them.

Section: Geological Settingsmentioning

confidence: 99%

Site classification of seismic recording stations of Garhwal region of earthquake early warning system for Uttarakhand, India

Kumar

Kamal

et al. 2022

Vietnam J. Earth Sci.

Self Cite

“…The soil strata's layering information was collected from available literature (Pandey et al 2016(Pandey et al , 2021. Similarly, the dynamic properties for the corresponding soil type of each layer are selected from the literature.…”

Section: Equivalent Linear 1-d Ground Response Analysis (Theoretical ...mentioning

confidence: 99%

“…VS profiles of the Indian sites are obtained from the available literature (Pandey et al 2016(Pandey et al , 2021, and Kik-Net sites are obtained from the webpage http://www.kyoshin.bosai.go.jp, which were used for ground response analysis. Multiple ground response analysis was performed for each site using VS profiles up to different depths extracted from the original VS profile (Figure 1)…”

Section: Site Classification and Analysismentioning

confidence: 99%

“…This study attempts to formulate a rationale for estimating a value that can be used as a Half-space/Reference site (in terms of VS) for a particular site depending upon proxies such as VS,30 and fundamental frequency obtained from Horizontal to Vertical spectral ratio of ambient vibration record. Available data from 62 stations of Indian strong-motion networks (Pandey et al 2016(Pandey et al , 2021and a few Japanese Kik-Net stations are used for this study.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Selection of an appropriate bedrock for site amplification studies

Jakka

2022

Nat Hazards

Self Cite

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/halfspace/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.

“…The sites used in this study belong to NEHRP site classes C and D. For this study, these sites were further divided into six groups in terms of VS,30 and depth of engineering bedrock (EB) (EB is considered as the first layer which has VS greater than 760 m/s) as follows; 235 The details of sites belonging to the Indian strong motion network and Japanese network are 242 presented in Table 1 and Table 2. 243 VS profiles of the Indian sites are obtained from the available literature (Pandey et al 2016(Pandey et al , 2021, and Kik-Net sites are obtained from the webpage http://www.kyoshin.bosai.go.jp, which were used for ground response analysis. Multiple ground response analysis was performed for each site using VS profiles up to different depths extracted from the original VS profile (Figure 1) to study the bedrock effect.…”

Section: Site Classification and Analysismentioning

confidence: 99%

Selection of an Appropriate Bedrock for Site Amplification Studies.

Jakka

2021

Preprint

Self Cite

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.