Evaluation of Average Shear-wave Velocity Estimation Methods of Multi-layered Strata Considering Site Period

2019 ◽  
Vol 23 (3) ◽  
pp. 191-199
Author(s):  
Dong-Kwan Kim ◽  
2021 ◽  
pp. 875529302110010
Author(s):  
Sameer Ladak ◽  
Sheri Molnar ◽  
Samantha Palmer

Site characterization is a crucial component in assessing seismic hazard, typically involving in situ shear-wave velocity ( VS) depth profiling, and measurement of site amplification including site period. Noninvasive methods are ideal for soil sites and become challenging in terms of field logistics and interpretation in more complex geologic settings including rock sites. Multiple noninvasive active- and passive-seismic techniques are applied at 25 seismograph stations across Eastern Canada. It is typically assumed that these stations are installed on hard rock. We investigate which site characterization methods are suitable at rock sites as well as confirm the hard rock assumption by providing VS profiles. Active-source compression-wave refraction and surface wave array techniques consistently provide velocity measurements at rock sites; passive-source array testing is less consistent but it is our most suitable method in constraining the rock VS. Bayesian inversion of Rayleigh wave dispersion curves provides quantitative uncertainty in the rock VS. We succeed in estimating rock VS at 16 stations, with constrained rock VS estimates at 7 stations that are consistent with previous estimates for Precambrian and Paleozoic rock types. The National Building Code of Canada uses solely the time-averaged shear-wave velocity of the upper 30 m ( VS30) to classify rock sites. We determine a mean VS30 of ∼ 1600 m/s for 16 Eastern Canada stations; the hard rock assumption is correct (>1500 m/s) but not as hard as often assumed (∼2000 m/s). Mean variability in VS30 is ∼400 m/s and can lead to softer rock classifications, in particular, for Paleozoic rock types with lower average rock VS near the hard/soft rock boundary. Microtremor and earthquake horizontal-to-vertical spectral ratios are obtained and provide site period classifications as an alternative to VS30.


1993 ◽  
Author(s):  
F. Lefeuvre ◽  
P. Desegaulx ◽  
M. L. Baratin

2011 ◽  
Vol 50 (7) ◽  
pp. 07HF07 ◽  
Author(s):  
Takashi Miwa ◽  
Raj Kumar Parajuli ◽  
Ryosuke Tomizawa ◽  
Yoshiki Yamakoshi

2006 ◽  
Vol 23 (1) ◽  
pp. 57s-68s ◽  
Author(s):  
Masashi MATSUOKA ◽  
Kazue WAKAMATSU ◽  
Kazuo FUJIMOTO ◽  
Saburoh MIDORIKAWA

2019 ◽  
Vol 16 (1) ◽  
pp. 105-115 ◽  
Author(s):  
Yahua Yang ◽  
Xingyao Yin ◽  
Gang Gao ◽  
Zhixian Gui ◽  
Bin Zhao

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Dalia Munaff Naji ◽  
Muge K. Akin ◽  
Ali Firat Cabalar

Assessment of seismic site classification (SSC) using either the average shear wave velocity (VS30) or the average SPT-N values (N30) for upper 30 m in soils is the simplest method to carry out various studies including site response and soil-structure interactions. Either the VS30- or the N30-based SSC maps designed according to the National Earthquake Hazards Reduction Program (NEHRP) classification system are effectively used to predict possible locations for future seismic events. The main goal of this study is to generate maps using the Geographic Information System (GIS) for the SSC in Kahramanmaras city, influenced by both East Anatolian Fault and Dead Sea Fault Zones, using both VS30 and N30 values. The study also presents a series of GIS maps produced using the shear wave velocity (VS) and SPT-N values at the depths of 5 m, 10 m, 15 m, 20 m, and 25 m. Furthermore, the study estimates the bed rock level and generates the SSC maps for the average VS values through overburden soils by using the NEHRP system. The VS30 maps categorize the study area mainly under class C and limited number of areas under classes B and D, whereas the N30 maps classify the study area mainly under class D. Both maps indicate that the soil classes in the study area are different to a high extent. Eventually, the GIS maps complied for the purpose of urban development may be utilized effectively by engineers in the field.


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