A Terrain-Based Site-Conditions Map of California with Implications for the Contiguous United States

Yong, Alan; Hough, Susan E.; Iwahashi, Junko; Braverman, Amy

doi:10.1785/0120100262

Cited by 105 publications

(90 citation statements)

References 62 publications

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“…The color version of this figure is available only in the electronic edition. types into 16 categories, which were then linked by Yong et al (2012) to log-average V S30 values within the categories using data from California. Figure 6 shows the ranges of V S30 provided by Wald and Allen (2007) as a function of the 30 arcsec gradient, along with the data from the Hellenic PDB.…”

Section: Proxy-based V S30 Estimationmentioning

confidence: 99%

“…When it is necessary to estimate V S30 for sites lacking such data, given currently available proxy relationships (including those in this paper), there are three options for sites in Greece: (1) the gradient-based approach of Wald and Allen (2007), (2) the terrain-based approach of Yong et al (2012) with the updated category means shown in Figure 5, and (3) the geology and gradient proxy presented in the previous section.…”

Section: Implementation Proxies and Weightingmentioning

confidence: 99%

See 1 more Smart Citation

Compilation of a Local VS Profile Database and Its Application for Inference of VS30 from Geologic- and Terrain-Based Proxies

Stewart¹,

Klimis²,

Savvaidis³

et al. 2014

Bulletin of the Seismological Society of America

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The time-averaged shear-wave velocity in the upper 30 m of a site (V S30 ) is commonly used for ground-motion prediction. When measured velocities are unavailable, V S30 is estimated from proxy-based relationships developed for application on global or local scales. We describe the development of a local relationship for Greece, which begins with compilation of a profile database (PDB) from published sources and engineering reports. The PDB contains 314 sites; 238 have profile depths ≥ 30 m and 59 are within 100 m of accelerographs. We find existing relations for extrapolating a time-averaged velocity for depths less than 30 m to V S30 to overpredict V S30 . We present equations for these extrapolations.We then compile proxies for PDB sites, including terrain type, surface geology, and surface gradients at 30 and 3 arcsec resolution (from radar-derived digital elevation models [DEMs]). When checked against ground survey data, we find ground elevations from 3 arcsec DEMs to be more accurate relative to survey data than alternative 30, 9, and 1 arcsec DEMs. Drawing upon expert opinion, we develop geologic categories based on age, gradation, and depositional environment and assign such categories to PDB sites. We find an existing 30 arcsec gradient-based global model to be biased relative to local V S30 data for gradients >∼0:05 m=m. Bias relative to a California model is also found for four of the eight well-populated geomorphic categories, and new (local) values are provided. We find statistically significant effects of the 3 arcsec gradient on V S30 for Quaternary and Tertiary materials but no gradient effect for those from the Mesozoic. Among Quaternary sediments, Holocene, mapped Quaternary (age unspecified), and mixed/fine-gradation materials exhibit consistent V S30 -gradient trends, whereas Pleistocene and coarse-gradation sediments have faster velocities. For the study region, we recommend use of the modified terrain-and geology-based methods in combination for proxy-based V S30 estimation.

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Section: Proxy-based V S30 Estimationmentioning

confidence: 99%

Section: Implementation Proxies and Weightingmentioning

confidence: 99%

Compilation of a Local VS Profile Database and Its Application for Inference of VS30 from Geologic- and Terrain-Based Proxies

Stewart¹,

Klimis²,

Savvaidis³

et al. 2014

Bulletin of the Seismological Society of America

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“…Iwahashi et al [46] presented a correlation between V S30 measurements and several topographic parameters, including topographic heights, slope gradient, local convexity, and surface texture. Other authors have proposed different approaches based on geomorphological units [47], geotechnical categories [48] and geological units [49][50][51], as a proxy for V S30 assessment. More recently, Thompson et al [52] proposed a V S30 map for California, United States, using a hybrid geostatistical approach to account for geology, topography, and site-specific shear wave velocity measurements.…”

Section: Assessment Of Seismic Site Effectsmentioning

confidence: 99%

Geospatial Big Data-Based Geostatistical Zonation of Seismic Site Effects in Seoul Metropolitan Area

Kim

Sun

Cho

2017

IJGI

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Seismic site effects are influenced mainly by geospatial uncertainties corresponding to geological or geotechnical spatial variance. Therefore, the development of a geospatial database is essential to characterize site-specific geotechnical information in multiscale areas and to optimize geospatial zonation methods with potentially high degrees of spatial variability based on trial-and-error geostatistical assessments. In this study, a multi-source geospatial information framework, which included the construction of a big data platform, estimation of geostatistical density, optimization of the geostatistical interpolation method, assessment of seismic site effects, and determination of geospatial zonation for decision making, was established. Then, this framework was applied to the Seoul metropolitan area, South Korea. The GIS-based framework was established to develop the geospatial zonation of site-specific seismic site effects before considering the local characteristics of site effects dependent on topographic or geological conditions, based on a geospatial big-data platform in Seoul. The zonal conditions were composed of geo-layers, site effect parameters, and other multi-source geospatial maps for each administrative area, and infrastructure was determined based on the integration of the optimized geoprocessing framework.

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“…In order to overcome this limitation, other data such as geological data, and measured V S30 data can be used jointly in V S30 calculation. In the early years of the twenty-first century, scientists studied the correlation between V S30 and other data such as surficial geology (e.g., Romero and Rix, 2001;Wills and Clahan, 2006); topographic slope (e.g., Wald and Allen, 2007;Allen and Wald, 2009); geomorphologic terrain mapping from satellite imagery (e.g., Yong et al, 2008;Yong et al, 2012). These studies tried to create more accurate and precise V S30 maps from the available data, then estimated the potential amplification due to site conditions in the affected or potentially affected area.…”

Section: Introductionmentioning

confidence: 99%

Methods for constructing VS30 maps from geology, borehole and topography data

2016

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The average shear wave velocity in the upper 30 meters of a soil profile (V S30 ) is used in building codes to separate sites into classes for the purpose of earthquake engineering design. In this paper, a method of Thompson E.N. and Wald D.J. (2012) was applied to build a VS30 map of Ho Chi Minh city using, many different data such as geologic, topographic and shear wave velocities derived from the Standard Penetration Test (SPT) data of 104 boreholes. The V S30 values are mainly within two ranges of 0 -180 m/s and 180 -240 m/s corresponding to two site classes of type D and C, respectively, according to the soil classification in Vietnam Construction Code TCVN 9386:2012. The site class of type C is mainly distributed in the districts located in the northern area of Ho Chi Minh city, while the soft soil with V S30 < 180 m/s is concentrated in the south of the city. This result shows that this method can reduce the uncertainty of V S30 map by up to 11.4% relative to the topography slope-only approach. Moreover, the average topographic slope of Ho Chi Minh city area is about 0.0024. It implies that Ho Chi Minh city area is in a stable continental region, which is suitable to apply ground motion prediction equations developed for seismic stable regions for the purpose of seismic hazard assessment. Our study is a prerequisite for the wide application of this method to build V S30 maps for other areas in Vietnam.

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A Terrain-Based Site-Conditions Map of California with Implications for the Contiguous United States

Cited by 105 publications

References 62 publications

Compilation of a Local VS Profile Database and Its Application for Inference of VS30 from Geologic- and Terrain-Based Proxies

Compilation of a Local VS Profile Database and Its Application for Inference of VS30 from Geologic- and Terrain-Based Proxies

Geospatial Big Data-Based Geostatistical Zonation of Seismic Site Effects in Seoul Metropolitan Area

Methods for constructing VS30 maps from geology, borehole and topography data

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