Multichannel Analysis Of Surface Waves Method Research Articles

Near-surface evaluation of Bora office area using MASW methods on land-streamer

A limited seismic investigation of the Bora Office Area, was conducted using multiple seismic methods including multi-channel analysis of surface waves (MASW), using land streamer originally designed by the author. The main feature of the land streamer tool is the non-stretch woven belt on which geophone units are mounted to form a multichannel geophone array similar. As a result, it was concluded that it might be possible to avoid higher-mode contaminantion at low frequencies at sites with hight (Vs), it can be seen that the distribution of Vs values varies over the range of 240 m/s to 420 m/s. In general, can be divided into 2 layers based on the value of Vs 100 - 250 m/s as soft rock and > 250 m/s as hard rock. There is a soft rock at a depth range of 0 to 5 m with a velocity value of 140-260 m/s, and hard rock layers at a depth range of below 5m with a velocity value of 280 - 400 m s.

Characterization of Sobradinho landslide in fluvial valley using MASW and ERT methods

Landslides can substantially impact the fluvial systems, which is why the continuous mapping of their extent, evolution and stability assessment is crucial. However, in such environments, material identification (e.g. colluvium) and subsurface characterization by the methods used for geologic mapping and geotechnical investigation is often a challenging task. Thus, these classical invasive methods may benefit from geophysical techniques to enable and enhance our understanding of the subsurface in these areas. To examine such integrated approach, Multi-Channel Analysis of Surface Waves (MASW) combined with Electrical Resistivity Tomography (ERT) were applied on a geomorphologically active fluvial valley in Sobradinho (the Federal District of Brazil). The subsurface materials showed a specific range of resistivity values as dry soil, saprolite, and landslide slip surface. The 1D shear wave velocity (Vs) model showed an increasing trend of Vs with depth at a location away from the landslide mass, while the longitudinal profile (over the landslide) showed an anomalous change in Vs (~ 250 to 400 m/sec). Based on the existing information about the landslide, the ERT appeared to be an effective method over MASW. This study shows how the integration of geophysical data with the geological and geotechnical investigation helps to obtain a more realistic or unambiguous model of the subsurface.

Influence of Source Energy and Stacking on Active MASW Method Dispersion Image

The study investigates the influence of source weight, type of source plate and number of stacking on the resolution of the dispersion image obtained from the active Multichannel Analysis of Surface Waves (MASW) method at peat soil condition. Fundamental-mode dispersion curve determination is governed by the optimum configuration of the active MASW method. Optimum configuration will ensure reliable inverted shear wave velocity profile. The heterogeneity and problematic characteristics of peat soil provide challenges on the MASW survey. Based on the field tests conducted, the effect of the source weight was significant. Heavier source weight relatively increases the dispersion image resolution especially at lower frequencies but sacrificing the resolution at higher frequencies. Therefore, heavier source weight (i.e. 7 kg sledgehammer) was recommended for deeper depth of investigation with little concern on the shallow depth. The use of rubber plate also contributed to the increases of energy accumulation at lower frequencies. Increasing number of stacking increases the overall energy band as the stacking allows significant suppression of the ambient noise. 5 to 10 stacks were recommended for peat soil condition. Finally, overall comparison between the dispersion images obtained at both locations shows that thicker peat soil layer results in lower resolution and low signal-to-noise ratio dispersion image.

Integration of the GNSS method and borehole camera to model the resulting spherical cavity generated by the main charge blast in clay

A depth camera was used to record the spherical cavity which occurred during blasting in clay soil. For this purpose, the integration of the Global Navigation Satellite System (GNSS) method was applied in addition to the depth camera and the laser, to determine the resulting spherical cavity. The expanded spherical cavity, formed after the blasting of the explosive charge in the bottom of the borehole, was measured by a depth camera-laser system. The GNSS measurement method was instrumental for obtaining the coordinates of the borehole. The Multichannel Analysis of Surface Waves (MASW) measurement method was also used during the study. Shear wave velocities (V S ) were calculated using MASW method to evaluate the dynamic properties of the clay soil along the in-situ profiles. The results obtained in this way, showed that there was an increase in the stiffness of the surrounding clay soil after blasting. The main objective of the study was to determine the resulting shapes and volume of the occurred cavities. For a more detailed graphical interpretation, an application was developed, which calculates the coordinates, shape and volumes of the formed spherical cavity.

MASW survey to estimate the unit weight of municipal solid waste at a landfill in Brazil

Non-invasive and non-destructive geophysical methods, such as the multichannel analysis of surface waves (MASW), can effectively provide useful information about the mechanical properties (stiffness and unit weight) of municipal solid waste (MSW), during and after landfill operation, for environmental monitoring and engineering analysis. This paper aims to address the results of a seismic survey performed at a sanitary landfill located 40 km north of Rio de Janeiro, Brazil, to image shear-wave velocity profiles to a depth of about 20 m. Seismic data were collected using the MASW method, performing an active and passive combined survey. Shear-wave velocities were used to compute the in situ unit weight distribution of MSW according to the empirical model proposed by Zekkos et al. Results indicated a two-layer model in which the bottom high-velocity layer is stiffer and denser than the top low-velocity layer. Despite the fact that the unit weight appeared to be underestimated for the upper low-velocity layer, model predictions may be graded qualitatively as excellent and potentially more accurate with well-calibrated parameters.

Mapping Subsurface Conditions and Detecting Seepage Channels for an Embankment Dam Using Geophysical Methods: A Case Study of the Kinion Lake Dam

Capacitively-Coupled Resistivity (CCR), Electrical Resistivity Tomography (ERT), and seismic surface wave testing using Love and Rayleigh waves were performed on Kinion Lake Dam, an embankment dam that has historically experienced significant seepage and internal erosion issues. The goal of this study is to detect seepage locations in the embankment dam for remediation purposes and map bedrock location across the area using nondestructive geophysical measurements. Surveys were completed along the crest and downstream toe of the dam to map subsurface conditions with a focus on seepage detection. The seismic surface wave data were analyzed using two different methods: Multichannel Analysis of Surface Waves (MASW) and Full Waveform Inversion (FWI). Both MASW and FWI methods were shown to be capable of resolving the bedrock layer below the dam, but the FWI method, provided a higher resolution image of the subsurface conditions compared to MASW method. However, the MASW and FWI provided little guidance regarding the seepage path through the dam. The CCR and ERT surveys, on the other hand, were shown to be very valuable for seepage detection. The seepage paths of the embankment dam were detected by comparing the resistivity measurements acquired in a wet winter and a dry summer. These seepage regions correspond well with previous sinkholes observed in the pool area following a drought. Additionally, new drilling in the two regions which showed differences in resistivity indicated the areas contained highly fractured limestone with evidence of solution cavities. It seems that the highly fractured limestone becomes fully saturated during the wet season causing very low resistivity values for these layers in wet seasons, but it quickly loses the water during the dry season leading to a highly resistive material in dry seasons. Therefore, seasonal resistivity measurements can be considered as a useful method for locating potential weak zones of earthen hydraulic structures in a cost-effective and timely manner.

Comparison of MASW and seismic interferometry with use of ambient noise for estimation of S-wave velocity field in landslide subsurface

This study presents a comparison of data acquisition, processing and interpretation between passive seismic interferometry (SI) and active multichannel analysis of surface waves (MASW) methods, both using surface waves for estimation S-wave velocity field. Measurements have been taken in the same geological engineering conditions on Just-Tegoborze landslide on the south of Poland. This comparison study has an important meaning from landslide hazard evaluation point of view. The landslide is located in Magura Nappe in Outer (Flysch) Carpathians. SI was based on registration of local seismic noise generated by high traffic on the state road which intersects the landslide. The main processing step was cross-correlation of seismic noise between every pair of receivers. It led to obtain series of empirical Green’s functions for Rayleigh surface wave. However, in MASW method, seismic energy was released by an impact of 5 kg sledgehammer in a metal plate. Both methods included analysis of dispersion curves of Rayleigh surface wave. The inversion of picked fundamental modes was applied using genetic algorithm and resulted in 1D S-wave velocity models. The last step of interpretation included model visualization as the 2D S-wave velocity sections for studied profiles. Both MASW and SI methods allowed to estimate S-wave velocity field in Just-Tegoborze landslide subsurface. Dispersion images obtained from both methods provided similar phase velocity and frequency ranges. On S-wave velocity sections, the greater depth range was observed for SI method; however, lateral resolution was better for MASW. Slip surfaces in colluvial layer were not observed on either SI or MASW S-wave velocity sections. Only results obtained from SI allowed to distinguish probable slip surface located deeper, i.e. on the contact with less weathered flysch bedrock.

Volcanic Sediment Layer of Mount Samalas 1257 AD Modeling Based on Seismic Data

Research to determine model of sediment volcanic layer of Mountain Samalas 1257 AD has been conducted in Lombok Island. Modeling based to surface wave velocity data which collect use MASW (multichannel analysis of surface wave) method. The method has applied at 6 locations in southern part relatively and models were made on southern and southeastern of eruption source. Grouping of volcanic layer was based on IBC 2003 (ICC, 2003), TSC, 1998 (Ministry of Public Works and Settlement Government of Republic of Turkey, 1998) criteria. Result of modeling was verified using outcrop at the measurement of seismic area. Volcanic layer groups that detect are C, D, E type which have velocity less than 400 ms-1 and it’s thickness less than 50 meters. The volcanic layer group consist of sand, kerikil, clay, batuapung, volcanic ash, and alluvium. All of types of volcanic rocks has founded at all seismic measurement locations with different thickness and composition.

A Resolution Enhancement of Rayleigh Wave Dispersive Imaging using Modified Phase-Shift Method

Multi-channel analysis of surface wave (MASW) method is an efficient tool for obtaining vertical shear wave profile. One of the key in the steps in the MASW method is generate a dispersion curves. To generate dispersion energy, the acquired shot gathers data have been transformed from the time-space (t-x) domain to the frequency-phase velocity (f-v) domain using 2D wavefield transformation so that the dispersion curve can be determined by picking the peak of dispersion energy. In this paper, we proposed a modified phase-shift method to increase the resolution of Rayleigh wave dispersive imaging so that the accuracy of the dispersion curve determination becomes higher. This method added processing step on the conventional phase-shift method. The algorithm is written in Matlab environment. We compared this method with the conventional phase-shift and frequency-wavenumber (F-K) method and applied to synthetic and real data. We used DISECA program in Matlab to generate synthetic waveforms. Our results from the synthetic and real data show that modified phase-shift method can improve the dispersion energy imaging resolution better than the conventional phase-shift and F-K method.

Interfacial Debonding Detection for Rectangular CFST Using the MASW Method and Its Physical Mechanism Analysis at the Meso-Level

In this study, the transient multichannel analysis of surface waves (MASW) is proposed to detect the existence, the location and the length of interface debonding defects in rectangular concrete-filled steel tubes (CFST). Mesoscale numerical analysis is performed to validate the feasibility of MASW-based interfacial debonding detection. Research findings indicate that the coaxial characteristics in the Rayleigh wave disperse at the starting point of the debonding area and gradually restores at the end of the defect. For healthy specimens, the surface wave mode in CFST is closer to the Rayleigh wave. However, it can be treated as a Lamb wave since the steel plate is boundary-free on both sides in the debonding area. The displacement curves are further investigated with forward analysis to obtain the dispersion curves. The mesoscale numerical simulation results indicate that the propagation characteristic of the surface wave is dominated by the debonding defect. The detectability of interfacial debonding detection for rectangular CFST using the MASW approach is numerically verified in this study. The proposed MASW-based nondestructive testing technique can achieve bond-slip detection by comparing the variation trend of the coaxial characteristics in the time-history output signals and the dispersion curves obtained from the forward analysis, for avoiding misjudgment of the experimental observations.

Application of passive multichannel analysis of surface waves method at sites close to underground railways - Problems and a case study

The Passive Multichannel Analysis of Surface Waves (MASW) method is a non-intrusive and cost effective technology adopted in civil and earthquake engineering for site geological and geotechnical survey. However, the application of passive MASW method under urban environments meets some challenges. One of interesting problems is associated with underground railways, which can be treated theoretically as buried sources. Since Rayleigh wave energy is dominant among that of surface waves, it is critical to design a proper geophone configuration during field tests at a site close to the metro line to ensure significant Rayleigh wave energy and therefore reliable dispersion images. This paper studied the propagation of Rayleigh waves generated from a buried source and proposed an empirical formula to estimate the nearest offset, which was then verified by numerical simulations. A case study was implemented in Shanghai, China at a site close to a subway line. With a linear spread geophone configuration, the influence of different parameters, including nearest offset, spread length and geophone interval, was investigated regarding their influences on dispersion images. Field tests were conducted by following the geophone configuration designed based on the proposed estimation method. The one dimensional (1D) shear velocity structure, being inverted from field vibration measurements, matches relatively well with the geologic feature obtained from borehole testing. Study results are expected to help facilitate the application of the passive MASW method for cases in which Rayleigh waves are generated by the buried source like underground traffics in cities.

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

On May 27th2006, 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.

Soil characterization of Bornova Plain (Izmir, Turkey) and its surroundings using a combined survey of MASW and ReMi methods and Nakamura’s (HVSR) technique

Structural damage which occurs during earthquakes is related to both the soil dynamic behavior attributes and soil response spectrums. Therefore, soil characterization based of S-wave velocity (Vs) is one of the prime factors to estimate damage and hazards. In this study, multi-channel analysis of surface waves (MASW) and refraction microtremor (ReMi) methods have been applied to estimate Vs values of the area located east of Izmir Bay. Based on the estimated Vs values, two- and three-dimensional shear-wave velocity and the maximum shear modulus maps at various depths down to 50 m were prepared. To study the relationship between the predominant period of the soil and shear-wave velocity values, a horizontal-to-vertical (H/V) spectral ratio method using Nakamura’s technique has been applied. Groundwater level, standard penetration test (SPT-N30) and Poisson ratio values were also obtained from previous geotechnical borehole data in the study area. In addition, we calculated building periods using the empirical relationship between height (or number of floors) of buildings and predominant period of the buildings to examine soil-structure resonance. According to the National Earthquake Hazard Reduction Program (NEHRP; 1997) soil classification, the study site consists of B-, C- and F-type soils. Risk maps were created using dynamic properties of the soil.

Shear‐wave velocity structure from MASW and SPAC methods: The case of Adra town, SE Spain

ABSTRACTThe damage distribution in the town of Adra (south‐eastern Spain) during the 1993 and 1994 Adra earthquakes of magnitude Mw~5.0 and maximum intensity degree of VII (European Macroseismic Scale) was mainly concentrated in the southeast sector, where the low‐diagenetic (soft) sediments outcrop. As new urbanizations are being planned in this sector, a soil classification based on the shallow shear‐wave velocity () structure is needed. For the purpose of earthquake disaster mitigation, the Spatial Autocorrelation (SPAC) and the Multichannel Analysis of Surface Waves (MASW) methods were used to propose integrated 2D models for the seismic response characterization of the shallow geology. Joint inversion of H/V spectral ratios of ambient noise, interpreted under the Diffuse Field Approach and the dispersion curves derived from the SPAC method allowed us to obtain more constrained models. Both SPAC and MASW methods provided similar results for the surveyed geological formations. From these models, a classification of the geological formations was carried out in terms of values and Eurocode 8 (European Committee for Standardization ) classes. Lower values in the 180‐360 m/s range were found in the southeastern sector of the town, where soft sediments outcrop and some building damage was reported during the 1993‐1994 earthquakes. The highest values exceeding 800 m/s appear in the northern sector, where the hardest rocks outcrop and no building damage was reported. The combination of the well‐suited database prepared for different geological formations with the 1:5,000 scale geological mapping was an important step to obtain the detailed soil microzonation map of Adra. This approach offered a new predictive insight into the building damage distribution, which would contribute to the appropriate urban planning for the future growth of the town.

Application of 2D full-waveform tomography on land-streamer data for assessment of roadway subsidence

Roadways are key components of the modern transportation system. Therefore, assessment of roadway subsidence is critical to the health and safety of the traveling public. Existing seismic refraction and waveform tomography methods can be used for subsidence evaluation; however, the data acquisition time is significant because they require multiple source impacts (shots) along a test line. To mitigate the negative impact caused by closing the traffic flow under seismic testing, a land-streamer seismic testing system and waveform analysis are developed. An existing 2D Gauss-Newton full-waveform inversion (FWI) method is extended for analysis of the land-streamer waveform data. The main advantage of using land-streamer waveform data is that geophones are not coupled to test materials and source-receiver offsets are fixed; thus, the whole test system can be moved along the roadway quickly for data acquisition. To demonstrate the effectiveness of land-streamer waveform data, the FWI method was tested on synthetic and field data sets. The synthetic result reveals that buried voids can be well-characterized by the land-streamer waveform analysis. Field data were collected on asphalt pavement using a 24 channel land streamer and a propelled energy generator to induce seismic wave energy. The test system was towed by a pickup truck along a roadway with an on-going subsidence (repaired sinkhole). The data were collected over 277.5 m distance at a 3 m interval, and the total data acquisition time was approximately 1 h. The field data result indicates that the waveform analysis was able to delineate low-velocity soil zones and laterally variable bedrock. The FWI results are also compared with multichannel analysis of surface wave (MASW) results. The 2D [Formula: see text] profiles from the FWI and MASW methods are consistent; however, the FWI method provides more detailed information ([Formula: see text] of [Formula: see text] cells) of low-velocity anomalies for assessment of roadway subsidence.

Soil classification for seismic site effect using MASW and ReMi methods: A case study from western Anatolia (Dikili -İzmir)

The study area is located in the northern part of Izmir, Western Turkey, prone to an active tectonic extensional regime and includes typical features of sedimentary basins, horst-grabens surrounded by a series of normal and strike-slip faults. In September 1939 the Dikili (Kabakum) earthquake with a magnitude of Mw: 6.6 occurred and after this phenomenon, residents moved from the west of Dikili to the east (i.d. soft sediments to relative to rock area). A proper estimate of the earthquake-related hazard for the area is the main objective of this study. The site effect and soil engineering problems for estimating hazard parameters at the soil surface need to be carefully analyzed for seismic site classification and geo-engineering problems like soil liquefaction, soil settlement, soil bearing capacity and soil amplification. To solve the soil static and dynamic problems, shear-wave velocities have been used in a joint interpretation process; Multichannel Analysis of Surface Waves (MASW) and Refraction Microtremor (ReMi) analyses were conducted on 121 sites with 300×300 m grid size in an area of 60km2. It has been proposed that the probability of an earthquake with a magnitude of Mw: 6 occurring within 10years is 64%, when considering the Gutenberg-Richter model. This puts the region under an important earthquake risk. The estimated Vs30 values are ≤180m/s in the central and the northernmost part of the study area are showing an E type soil after the classification of NEHRP, where alluvial deposits are dominant. Vs30 values in the north and central part are between 180≤Vs≤360m/s suggesting a D type soil. In the southernmost part of the study area where volcanic rocks are widely distributed, Vs30 values range between 360 and 908m/s, corresponding to a C type and B type soil. The results show that soil liquefaction induced settlement and soil amplification are the most important problems in the south and the northernmost part of the study area, which is densely populated and encompasses the urbanized part of the study region.

Tool for analysis of multichannel analysis of surface waves (MASW) field data and evaluation of shear wave velocity profiles of soils

Multichannel analysis of surface waves (MASW) is a fast, low-cost, and environmentally friendly technique to estimate shear wave velocity profiles of soil sites. This paper introduces a new open-source software, MASWaves, for processing and analysing multichannel surface wave records using the MASW method. The software consists of two main parts: a dispersion analysis tool (MASWaves Dispersion) and an inversion analysis tool (MASWaves Inversion). The performance of the dispersion analysis tool is validated by comparison with results obtained by the Geopsy software package. Verification of the inversion analysis tool is carried out by comparison with results obtained by the software WinSASW and theoretical dispersion curves presented in the literature. Results of MASW field tests conducted at three sites in south Iceland are presented to demonstrate the performance and robustness of the new software. The soils at the three test sites ranged from loose sand to cemented silty sand. In addition, at one site, the results of existing spectral analysis of surface waves (SASW) measurements were compared with the results obtained by MASWaves.

Assessment of soil compaction properties based on surface wave techniques

Soil compaction plays an important role in every construction activities to reduce risks of any damage. Traditionally, methods of assessing compaction include field tests and invasive penetration tests for compacted areas have great limitations, which caused time-consuming in evaluating large areas. Thus, this study proposed the possibility of using non-invasive surface wave method like Multi-channel Analysis of Surface Wave (MASW) as a useful tool for assessing soil compaction. The aim of this study was to determine the shear wave velocity profiles and field density of compacted soils under varying compaction efforts by using MASW method. Pre and post compaction of MASW survey were conducted at Pauh Campus, UniMAP after applying rolling compaction with variation of passes (2, 6 and 10). Each seismic data was recorded by GEODE seismograph. Sand replacement test was conducted for each survey line to obtain the field density data. All seismic data were processed using SeisImager/SW software. The results show the shear wave velocity profiles increase with the number of passes from 0 to 6 passes, but decrease after 10 passes. This method could attract the interest of geotechnical community, as it can be an alternative tool to the standard test for assessing of soil compaction in the field operation.

Comparison of the Soil Dynamic Amplification Factor and Soil Amplification by Using Microtremor and MASW Methods Respectively

Single Station Microtremor method, which is widely used nowadays, is an effective and easy applicable method. In this study, dynamic amplification factor distributions of the study area were obtained using scenario earthquake parameters with single station microtremor data gathered at 112 points. In addition, a surface wave active method, which is known as MASW (Multichannel Analysis of Surface Waves), was applied at 43 profiles to calculate the soil amplification values. Dynamic amplification factor (DAF), soil amplification, the predominant soil period (PSP), geology and topography data of the study area were analysed together. Dynamic amplification factor and soil amplification values were obtained 2 or higher at about sea level parts of the study area which are generally composed of alluvial units. Additionally, in high altitude regions that are composed of volcanic rocks, relatively lower dynamic amplification factor and soil amplification values were obtained. The minimum amplification value in the study area was 1.15, while the maximum amplification value was 3.05 according to the dynamic amplification results and the soil amplification values were between 1.16 and 3.85 in harmony. It is seen that the obtained DAF values and the soil amplification values calculated from the seismic velocities are very similar to each other numerically and regionally. Because of this, it is concluded that the values of the soil amplification obtained by the MASW method and the calculated DAF values in this study are in harmony with each other. Although the depths of research in these two calculation methods are different from each other, the similarity of the results allows us to arrive at the result of how effective the ground layer is on the amplification. It has a great importance to calculate the amplification values and other dynamic parameters by in situ measurements for a planned plot because geological units can vary even at very short distances in heterogeneously distributed areas.

Determination of shear wave velocities in sediment deposits

This work aims to identify geotechnical characteristics at selected sites in Crete, Greece where strong ground motion stations of the Hellenic Accelerometric Network are installed. Particular emphasis was given in the determination of shear wave velocity profiles, so that the geotechnical classification of the sites in relation to their seismic response can be defined. The shear wave velocity was estimated using the multichannel analysis of surface waves (MASW) method along survey lines close to boreholes, drilled for site investigation purposes. In order to verify the reliability of MASW results, published relationships between shear wave velocity and standard penetration test values were considered. In addition, shear wave velocity measurements were conducted through laboratory tests using bender elements on undisturbed soil samples obtained during drilling. Results indicate that a combination of techniques for shear wave estimation may minimise the effects of uncertainties involved in application and assumptions of the MASW method.