scholarly journals APPLICATION OF MULTICHANNEL ANALYSIS OF SURFACE WAVES METHOD (MASW) IN AN AREA SUSCEPTIBLE TO LANDSLIDE AT UBATUBA CITY, BRAZIL

2012 ◽  
Vol 30 (2) ◽  
Author(s):  
Sérgio Bezerra Lima Júnior ◽  
Renato Luiz Prado ◽  
Rodolfo Moreda Mendes
Keyword(s):  
Comparative Analysis ◽  
Surface Waves ◽  
Unsaturated Soils ◽  
Complete Characterization ◽  
Dry Season ◽  
Soil Parameters ◽  
S Wave ◽  
Multichannel Analysis ◽  
Geotechnical Investigations ◽  
Masw Method

This paper presents results from the MASW method (multichannel analysis of surface waves) in a hill side area of unsaturated soils in the Ubatuba City,Brazil, a site where numerous mass movements have occurred. It discusses the influence of some acquisition parameters, such as, the natural frequency of geophones and minimum and maximum offsets in dispersion image results and does a comparative analysis of the results obtained in repeated tests carried out in the same place, under the same conditions, during the dry and rainy seasons. The comparative analysis for the inversion results in different periods showed that the values of S-wave velocity during the dry season were higher than those for the rainy season; these variations were attributed to the higher cohesion of the soil structure in the dry season. The final 1D velocity profile model with depth was consistent with the results of other geophysical and geotechnical investigations made. Although additional in situ and laboratory geotechnical tests, are necessary (to obtain soil parameters such as hydraulic conductivity, moisture content, soil suction, for example), for a complete characterization of the geotechnical properties of the investigated soil, the result shows that it is possible to use empirical correlations between the Vs profile, from the MASW method, and soil stiffness parameters in order to monitor areas susceptible to landslide.

Revisiting levees in southern Texas using Love-wave multichannel analysis of surface waves with the high-resolution linear Radon transform

2017 ◽  
Vol 5 (3) ◽  
pp. T287-T298 ◽  
Author(s):  
Julian Ivanov ◽  
Richard D. Miller ◽  
Daniel Feigenbaum ◽  
Sarah L. C. Morton ◽  
Shelby L. Peterie ◽  
...  
Keyword(s):  
High Resolution ◽  
Rayleigh Wave ◽  
Surface Waves ◽  
Radon Transform ◽  
Seismic Data ◽  
Love Wave ◽  
S Wave ◽  
Multichannel Analysis ◽  
Masw Method ◽  
Wave Methods

Shear-wave velocities were estimated at a levee site by inverting Love waves using the multichannel analysis of surface waves (MASW) method augmented with the high-resolution linear Radon transform (HRLRT). The selected site was one of five levee sites in southern Texas chosen for the evaluation of several seismic data-analysis techniques readily available in 2004. The methods included P- and S-wave refraction tomography, Rayleigh- and Love-wave surface-wave analysis using MASW, and P- and S-wave cross-levee tomography. The results from the 2004 analysis revealed that although the P-wave methods provided reasonable and stable results, the S-wave methods produced surprisingly inconsistent shear-wave velocity [Formula: see text] estimates and trends compared with previous studies and borehole investigations. In addition, the Rayleigh-wave MASW method was nearly useless within the levee due to the sparsity of high frequencies in fundamental-mode surface waves and complexities associated with inverting higher modes. This prevented any reliable [Formula: see text] estimates for the levee core. Recent advances in methodology, such as the HRLRT for obtaining higher resolution dispersion-curve images with the MASW method and the use of Love-wave inversion routines specific to Love waves as part of the MASW method, provided the motivation to extend the 2004 original study by using horizontal-component seismic data for characterizing the geologic properties of levees. Contributions from the above-mentioned techniques were instrumental in obtaining [Formula: see text] estimates from within these levees that were very comparable with the measured borehole samples. A Love-wave approach can be a viable alternative to Rayleigh-wave MASW surveys at sites where complications associated with material or levee geometries inhibit reliable [Formula: see text] results from Rayleigh waves.

Horizontal resolution of multichannel analysis of surface waves

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. EN51-EN66 ◽  
Author(s):  
Binbin Mi ◽  
Jianghai Xia ◽  
Chao Shen ◽  
Limin Wang ◽  
Yue Hu ◽  
...  
Keyword(s):  
Influencing Factors ◽  
Wave Velocity ◽  
Horizontal Resolution ◽  
Observation System ◽  
S Wave ◽  
Near Surface ◽  
Anomalous Body ◽  
Multichannel Analysis ◽  
Anomalous Bodies ◽  
Masw Method

The multichannel analysis of surface wave (MASW) method has been effectively and widely used to determine near-surface shear-wave velocity. Horizontal resolution of the MASW method represents the minimum horizontal length of recognizable geologic anomalous bodies on a pseudo-2D S-wave velocity [Formula: see text] section. Accurately assessing the achievable lateral resolution is one of the main issues in lateral variation reconstruction using the MASW method. It is difficult to quantitatively estimate the horizontal resolution of the MASW method because of the many influencing factors, such as parameters of the observation system, the depth of an anomalous body, and the velocity contrast between the anomalous body and the surrounding rocks. We first analyzed the horizontal resolution of the MASW method based on numerical simulation experiments. According to different influencing factors of the horizontal resolution, we established different laterally heterogeneous models and observation systems and then simulated several synthetic multichannel records with a finite-difference method along a linear survey line using the roll-along acquisition mode. After the extraction of dispersion curves of Rayleigh waves and inversion for S-wave velocity profiles for each synthetic shot gather, a pseudo-2D S-wave velocity section can be generated by aligning the 1D S-wave velocity models. Ultimately, we evaluated the horizontal resolution capability of the MASW method on pseudo-2D [Formula: see text] maps. Our numerical investigation results and field data analysis indicate that [Formula: see text] values on the maps are not the same as the true [Formula: see text] values for structures whose lateral dimension is shorter than a receiver spread length and that anomalous bodies, which are larger and have high velocity contrast, are easier to distinguish on [Formula: see text] maps with a shorter receiver spread length. The horizontal resolution decreases with the increasing depth and is approximately one-half of the shortest Rayleigh wavelength that can penetrate to the depth.

scholarly journals Multi-channel analysis of surface wave method for geotechnical site characterization in Yogyakarta, Indonesia

2019 ◽  
Vol 76 ◽  
pp. 03006
Author(s):  
Nwai Le Ngal ◽  
Subagyo Pramumijoyo ◽  
Iman Satyarno ◽  
Kirbani Sri Brotopuspito ◽  
Junji Kiyono ◽  
...  
Keyword(s):  
Surface Waves ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Rayleigh Waves ◽  
Influential Factors ◽  
Multichannel Analysis ◽  
Average Shear ◽  
Channel Analysis ◽  
Masw Method

On May 27th 2006, Yogyakarta earthquake happened with 6.3 Mw. It was causing widespread destruction and loss of life and property. The average shear wave velocity to 30 m (Vs30) is useful parameter for classifying sites to predict their potential to amplify seismic shaking (Boore, 2004) [1]. Shear wave velocity is one of the most influential factors of the ground motion. The average shear wave velocity for the top 30 m of soil is referred to as Vs30. In this study, the Vs30 values were calculated by using multichannel analysis of surface waves (MASW) method. The Multichannel Analysis of Surface Waves (MASW) method was introduced by Park et al. (1999). Multi-channel Analysis of Surface Waves (MASW) is non-invasive method of estimating the shear-wave velocity profile. It utilizes the dispersive properties of Rayleigh waves for imaging the subsurface layers. MASW surveys can be divided into active and passive surveys. In active MASW method, surface waves can be easily generated by an impulsive source like a hammer, sledge hammer, weight drops, accelerated weight drops and explosive. Seismic measurements were carried out 44 locations in Yogyakarta province, in Indonesia. The dispersion data of the recorded Rayleigh waves were processed by using Seisimager software to obtain shear wave velocity profiles of the studied area. The average shear wave velocities of the soil obtained are ranging from 200 ms-1 to 988 ms-1, respectively.

scholarly journals COMBINED USE OF ACTIVE AND PASSIVE SURFACE WAVES FOR SHALLOW SUBSURFACE INVESTIGATION IN NOISY URBAN AREA OF SÃO PAULO CITY, BRAZIL

2016 ◽  
Vol 34 (1) ◽  
pp. 13 ◽  
Author(s):  
Claus Naves Eikmeier ◽  
Renato Luiz Prado ◽  
Fabio Taioli
Keyword(s):  
Surface Waves ◽  
Urban Areas ◽  
Joint Inversion ◽  
Traffic Noise ◽  
Sao Paulo ◽  
Invasive Technique ◽  
Dynamic Shear Modulus ◽  
São Paulo ◽  
S Wave ◽  
Masw Method

ABSTRACT. The dynamic shear modulus (Gdin) is important for geotechnical engineering, particularly for calculating the dynamic response of foundations. Gdin is determined from material densities and S-wave propagation velocity (VS). Usually, crosshole test is used for such determination. However, it is an expensive and invasive technique because it is based on drilling. The MASW method (Multichannel Analysis of Surface Waves) becomes an interesting option for being faster, more economical and easier to carry out. This paper presents results obtained with MASW method in a densely built up area with high traffic noise level in São Paulo city, Brazil. Results are compared with those obtained by crosshole test as well as geotechnical sounding data. The influence of some acquisition parameters was evaluated in data quality and final inversion result. Besides, it was also tested the passive mode test that is recording ambient noise. Best results were obtained by joint inversion of fundamental and higher curve modes extracted from stacked images generated from data acquired employing sledgehammer and passive sources. Final VS models were coherent with results obtained from crosshole seismic testing and mechanical sounding description, demonstrating MASWmethod can generate important information for geological and geotechnical investigation of urban areas. Keywords: MASW, seismic, Rayleigh wave, velocity profile, dispersion curve.RESUMO. O módulo de cisalhamento dinâmico (Gdin) é importante para a engenharia geotécnica, particularmente nos cálculos de fundações sujeitas a esforços dinâmicos. O Gdin é determinado a partir das densidades dos materiais e das velocidades de propagação das ondas S (VS). Normalmente se utiliza o ensaio crosshole, ensaio sísmico entre poços, para tal determinação, porém, trata-se de uma aquisição de execução dispendiosa. Este trabalho apresenta resultados obtidos com o método MASW em uma área densamente edificada e com alto nível de ruído de tráfego na cidade de São Paulo, Brasil, que são comparados com os obtidos por ensaio crosshole, assim como com dados de sondagem direta. Avaliou-se, também, a influência de alguns parâmetros de aquisição na qualidade do dado e no resultado final da inversão. Testou-se ainda a aquisição de dados no modo passivo, ou seja, registrando-se o ruído ambiental. Os melhores resultados foram obtidos utilizando-se inversão conjunta dos modos fundamental e superiores das curvas extraídas do empilhamento das imagens de dispersão dos dados gerados com as fontes marreta e passiva. Os modelos de VS obtidos foram coerentes com os resultados obtidos do ensaio sísmico crosshole e da descrição da sondagem mecânica, demonstrando que o método MASW pode gerar importantes informações para investigações geológicas e geotécnicas de áreas urbanas. Palavras-chave: MASW, sísmica, onda Rayleigh, perfil de velocidades, curva de dispersão. 

Multichannel analysis of surface waves (MASW) for offshore geotechnical investigations

2020 ◽  
Vol 272 ◽  
pp. 105649
Author(s):  
Michael Long ◽  
Andy Trafford ◽  
Tomás McGrath ◽  
Peter O'Connor
Keyword(s):  
Surface Waves ◽  
Multichannel Analysis ◽  
Geotechnical Investigations
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