Search

The seismicity in the SE Iberian Peninsula is distributed parallel to the coast in a well-developed strike-slip fracture system known as the Eastern Betic Shear Zone (EBSZ). This work focuses on the characterization of the shallow subsurface structure of the Algezares-Casas Nuevas Fault, within the Carrascoy Fault System of the EBSZ. The Carrascoy Fault borders the Guadalentín Depression to the south, which is a densely populated area with extensive agricultural activity. Therefore, this faults system represents a seismic hazard with significant social and economic implications. We have constructed two velocity-depth models based on P-wave tomography and Multichannel Analysis of Surface Waves (MASW) acquired from seismic reflection data. The resulting velocity models have allowed us to interpret the first ~250m depth and have revealed: i) the thickness of the critical zone; ii) the geometry of the Algezares-Casas Nuevas Fault; iii) the depth of the Messinian/Tortonian contact and iv) the presence of blind thrusts and damage zones under the Guadalentín Depression. Our results have also helped us to estimate an apparent vertical slip rate of 0.66±0.06m/ky for the Algezares-Casas Nuevas Fault since 209.1±6.2ka. Our results provide a methodological and backflow protocol to study the shallow subsurface of active faults, complementing previous geological models based on paleoseismological trenches, and can be used to improve the seismic hazard assessment of tectonically active regions around the world., Ministerio de Economía y Competitividad (MINECO), Ministerio de Ciencia e Innovación (MICINN), Generalitat de Catalunya, Universidad de Salamanca, Junta de Castilla y León/FEDER, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

The critical zone (CZ) represents the most-shallow subsurface, where the bio-, hydro-, and geospheres interact with anthropogenic activity. To characterize the thickness and lateral variations of the CZ, here we focus on the Eastern Betic Shear Zone (EBSZ), one of the most tectonically active regions in the Iberian Peninsula. Within the EBSZ, the Guadalentín Depression is a highly populated area with intensive agricultural activity, where the characterization of the CZ would provide valuable assets for land use management and seismic hazard assessments. To achieve this, we have conducted an interdisciplinary geophysical study along the eastern border of the Guadalentín Depression to characterize the CZ and the architecture of the shallow subsurface. The datasets used include Electrical Resistivity Tomography (ERT), first-arrival travel time seismic tomography, and multichannel analysis of surface waves (MASW). The geophysical datasets combined help to constrain the high-resolution structure of the subsurface and image active fault systems along four transects. The resulting geophysical models have allowed us to interpret the first ~150 m of the subsurface and has revealed: (i) the variable thickness of the CZ; (ii) the CZ relationship between the fault zone and topographic slope; and (iii) the differences in CZ thickness associated with the geological units. Our results provide a method for studying the shallow subsurface of active faults, complementing previous geological models based on paleo-seismological trenches, and can be used to improve the CZ assessment of tectonically active regions., Ministerio de Economía y Competitividad (MINECO), GEO3BCN-CSIC, KEMDIKBUDRISTEK of the Republic of Indonesia, GIPP-GFZ, Seismic Unix CWP (Center for Wave Phenomena, Colorado School of Mines), Lisbon University, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Geophysical methods including Multichannel Analysis of Surface Waves (MASW) using both Rayleigh and Love waves, P-wave refraction, Horizontal to Vertical Spectral Ratio (HVSR), Capacitively-Coupled Resistivity (CCR), Electrical Resistivity Tomography (ERT), Ground Penetration Radar (GPR), and Electromagnetic Ground Conductivity (EM31) were used for bedrock mapping and slope stability investigations for several ARDOT transportation projects. In Phase I, all geophysical methods were applied for two ARDOT test sites to investigate the advantages and limitations of each method. Based on the performance of each method in Phase I, the potential non-invasive geophysical methods best suited for slope stability investigations and bedrock mapping were identified. These methods were then implemented in Phase II for several ongoing ARDOT transportation projects. For slope stability with a shallow and complex bedrock topography, which is the case for most ARDOT projects, a combination of HVSR, MASW, and ERT or P-wave refraction was observed to be viable. For such sites, a 3D image of bedrock topography is a key factor required for the development of a detailed slope stability model. In this regard, the HVSR is proposed as an effective tool when used in conjunction with other geophysical methods to create a 3D map of bedrock topography in a simple, rapid, cost-effective, and accurate manner.

Obtaining knowledge about the structural, geotechnical and hydrogeological conditions of mining waste storage facilities (e.g., tailing storage facilities, TSF) is an important task for mining waste management. From the existing applied geophysics techniques, high-resolution controlled source seismic methods are the most appropriate due to their superior spatial and depth resolution. However, the TSF areas are not often accessible for installation of seismic instruments and application of controlled source. Moreover, TSF areas in active mine sites are characterised by high-level of seismic and acoustic noise, produced by mining operations and other human activities at mine sites. In this study, we show that these problems can be addressed by utilizing passive seismic interferometry, in which cross-correlation of ambient seismic noise is used to obtain the Empirical Green’s function (EGF’s) of the studied medium. We used this method to evaluate seismic velocities in the TSF and in the near-surface bedrock at the site of the Pyhäsalmi underground mine in Finland. We used the ambient seismic noise recorded in two seismic experiments in the area. In the first experiment, the data were acquired in 2013 along a line 10 km long crossing the area of the underground mine. The second experiment was carried out in the TSF area in 2019. We obtained S-wave velocity models of both bedrock and the TSF by applying multichannel analysis of surface waves (MASW) to surface wave parts of Empirical Green’s Functions (EGFs). The analysis of autocorrelation functions of passive seismic data recorded on the TSF surface allowed to us retrieve reflected arrivals from the boundaries inside the TSF. At the same time, we used amplitudes of surface wave parts of EGF’s to obtain information about attenuation of surface waves in TSF. Our results show that passive seismic interferometry and interpretation of passive seismic data by different techniques can be a useful tool for inspection o

The seismicity in the SE Iberian Peninsula is distributed parallel to the coast in a well-developed strike-slip fracture system known as the Eastern Betic Shear Zone (EBSZ). This work focuses on the characterization of the shallow subsurface structure of the Algezares-Casas Nuevas Fault, within the Carrascoy Fault System of the EBSZ. The Carrascoy Fault borders the Guadalentín Depression to the south, which is a densely populated area with extensive agricultural activity. Therefore, this faults system represents a seismic hazard with significant social and economic implications. We have constructed two velocity-depth models based on P-wave tomography and Multichannel Analysis of Surface Waves (MASW) acquired from seismic reflection data. The resulting velocity models have allowed us to interpret the first ~250m depth and have revealed: i) the thickness of the critical zone; ii) the geometry of the Algezares-Casas Nuevas Fault; iii) the depth of the Messinian/Tortonian contact and iv) the presence of blind thrusts and damage zones under the Guadalentín Depression. Our results have also helped us to estimate an apparent vertical slip rate of 0.66±0.06m/ky for the Algezares-Casas Nuevas Fault since 209.1±6.2ka. Our results provide a methodological and backflow protocol to study the shallow subsurface of active faults, complementing previous geological models based on paleoseismological trenches, and can be used to improve the seismic hazard assessment of tectonically active regions around the world

The seismicity in the SE Iberian Peninsula is distributed parallel to the coast in a well-developed strike-slip fracture system known as the Eastern Betic Shear Zone (EBSZ). This work focuses on the characterization of the shallow subsurface structure of the Algezares-Casas Nuevas Fault, within the Carrascoy Fault System of the EBSZ. The Carrascoy Fault borders the Guadalentín Depression to the south, which is a densely populated area with extensive agricultural activity. Therefore, this faults system represents a seismic hazard with significant social and economic implications. We have constructed two velocity-depth models based on P-wave tomography and Multichannel Analysis of Surface Waves (MASW) acquired from seismic reflection data. The resulting velocity models have allowed us to interpret the first ~250m depth and have revealed: i) the thickness of the critical zone; ii) the geometry of the Algezares-Casas Nuevas Fault; iii) the depth of the Messinian/Tortonian contact and iv) the presence of blind thrusts and damage zones under the Guadalentín Depression. Our results have also helped us to estimate an apparent vertical slip rate of 0.66±0.06m/ky for the Algezares-Casas Nuevas Fault since 209.1±6.2ka. Our results provide a methodological and backflow protocol to study the shallow subsurface of active faults, complementing previous geological models based on paleoseismological trenches, and can be used to improve the seismic hazard assessment of tectonically active regions around the world.

The seismicity in the SE Iberian Peninsula is distributed parallel to the coast in a well-developed strike-slip fracture system known as the Eastern Betic Shear Zone (EBSZ). This work focuses on the characterization of the shallow subsurface structure of the Algezares-Casas Nuevas Fault, within the Carrascoy Fault System of the EBSZ. The Carrascoy Fault borders the Guadalentín Depression to the south, which is a densely populated area with extensive agricultural activity. Therefore, this faults system represents a seismic hazard with significant social and economic implications. We have constructed two velocity-depth models based on P-wave tomography and Multichannel Analysis of Surface Waves (MASW) acquired from seismic reflection data. The resulting velocity models have allowed us to interpret the first ~250m depth and have revealed: i) the thickness of the critical zone; ii) the geometry of the Algezares-Casas Nuevas Fault; iii) the depth of the Messinian/Tortonian contact and iv) the presence of blind thrusts and damage zones under the Guadalentín Depression. Our results have also helped us to estimate an apparent vertical slip rate of 0.66±0.06m/ky for the Algezares-Casas Nuevas Fault since 209.1±6.2ka. Our results provide a methodological and backflow protocol to study the shallow subsurface of active faults, complementing previous geological models based on paleoseismological trenches, and can be used to improve the seismic hazard assessment of tectonically active regions around the world.

The critical zone (CZ) represents the most-shallow subsurface, where the bio-, hydro-, and geospheres interact with anthropogenic activity. To characterize the thickness and lateral variations of the CZ, here we focus on the Eastern Betic Shear Zone (EBSZ), one of the most tectonically active regions in the Iberian Peninsula. Within the EBSZ, the Guadalentín Depression is a highly populated area with intensive agricultural activity, where the characterization of the CZ would provide valuable assets for land use management and seismic hazard assessments. To achieve this, we have conducted an interdisciplinary geophysical study along the eastern border of the Guadalentín Depression to characterize the CZ and the architecture of the shallow subsurface. The datasets used include Electrical Resistivity Tomography (ERT), first-arrival travel time seismic tomography, and multichannel analysis of surface waves (MASW). The geophysical datasets combined help to constrain the high-resolution structure of the subsurface and image active fault systems along four transects. The resulting geophysical models have allowed us to interpret the first ~150 m of the subsurface and has revealed: (i) the variable thickness of the CZ; (ii) the CZ relationship between the fault zone and topographic slope; and (iii) the differences in CZ thickness associated with the geological units. Our results provide a method for studying the shallow subsurface of active faults, complementing previous geological models based on paleo-seismological trenches, and can be used to improve the CZ assessment of tectonically active regions.

The deep structure of the Alhama de Murcia Fault (AMF) is characterized by means of the analysis of surface waves identified in shallow high resolution seismic reflection data. Multichannel analysis of surface waves (MASW) is used to unravel the 2-D S-wave velocity model and image the depth geometry of the fault system. The study area includes segments of the fault located in La Salud area. Two approaches have been used to achieve a well constrained velocity model in the AMF fault zone. Conventional seismic reflection processing work flow has been used to clean the seismic data and increase its S/N ratio. Occam’s approach has been used to invert the digitized surface wave dispersion curves. 1D shear wave velocity-depth profiles were estimated in shot and CDP domains. Relatively well resolved 2D velocity-depth models were obtained by com- posite of the 1D Velocity-depth functions. These composite 2D-velocity models are able to constrain the depth geometry of the fault zone up to 100 m depth. The fault zone is indicated by a relatively broad low velocity anomaly that correlates with the fault’s surface expression., La estructura profunda de la falla de Alhama de Murcia (AMF) ha sido caracterizada mediante el análisis de ondas superficiales identificados en datos de reflexión sísmica superficial de alta resolución. El análisis multicanal de ondas de superficie (MASW) es usado para desentrañar un modelo 2D de Vs y para obtener imágenes de la geometría del sistema de fallas en profundidad. El área de estudio incluye segmentos de la AMF ubicados en el área de La Salud. Se han utilizado dos enfoques para lograr modelos de velocidad bien restringidos de la zona de falla. Por un lado, se han limpiado los datos utilizado un flujo de procesado convencional diseñado para aumentar su ratio de señal/ruido. Por el otro, se ha usado el enfoque de Occam para invertir las curvas de dispersión de ondas de superficie digitalizadas. Los perfiles 1D de profundidad de las Vs fueron estimados en los dominios de disparo y de CDP. Se obtuvieron modelos de velocidad-profundidad 2D relativamente bien resueltos mediante la interpolación de las funciones de velocidad-profundidad 1D. Estos modelos de velocidad 2D ayu- dan a restringir en profundidad la geometría de la zona de falla hasta los 100 m que se caracteriza por una anomalía de baja velocidad relativamente amplia que se correlaciona en la superficie con la expresión de la falla., Ministerio de Ciencia e Innovación (MICINN), ICTJA-CSIC, Ministry of Education and Culture of the Republic of Indonesia, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Modern sensing systems such as distributed acoustic sensing (DAS) can produce massive quantities of geophysical data, often in remote locations. This presents significant challenges with regards to data storage and performing efficient analysis. To address this, we have designed and implemented efficient algorithms for two commonly utilized techniques in geophysical imaging: cross-correlations, and multichannel analysis of surface waves (MASW). Our cross-correlation algorithms operate directly in the wavelet domain on compressed data without requiring a reconstruction of the original signal, reducing memory costs and improving scalabiliy. Meanwhile, our MASW implementations make use of MPI parallelism and GPUs, and present a novel problem for the GPU.

Quick-clay landslides are important geohazards in Sweden, Norway and Canada. While they have been studied using various geotechnical and geophysical methods, only a handful of seismic surveys have been reported for their studies. Here, we reprocess active-source seismic data from a quick-clay landslide site in southwest Sweden to complement earlier studies of reflection imaging and first-break traveltime tomography with surface-wave dispersion analysis. Results suggest extremely low shear-wave velocities, even as low as 60–100 m/s. From a geotechnical perspective, this implies that the region classifies as a high-risk zone for landslides and construction purposes. High or anomalous values of Poisson's ratio (or similarly P- and S-wave velocity ratio) depict a zone within the normally consolidated sediments that likely represents a coarse-grained layer, thus confirming earlier results from a number of boreholes drilled in the study area. Overall, the results presented further support to the previous hypothesis that the coarse-grained layer plays a major role in the formation and creation of quick-clay landslides in the study area. Additionally, an attempt to model the distribution of potential quick clays along one of the seismic profiles is performed through a combination of the modelled geophysical properties and soil textures. This study illustrates the potential of seismic methods, and how the integration of multiple geophysical properties and different data handling strategies can help to accurately characterize regions susceptible to quick-clay landslides.

Quick-clay landslides are important geohazards in Sweden, Norway and Canada. While they have been studied using various geotechnical and geophysical methods, only a handful of seismic surveys have been reported for their studies. Here, we reprocess active-source seismic data from a quick-clay landslide site in southwest Sweden to complement earlier studies of reflection imaging and first-break traveltime tomography with surface-wave dispersion analysis. Results suggest extremely low shear-wave velocities, even as low as 60–100 m/s. From a geotechnical perspective, this implies that the region classifies as a high-risk zone for landslides and construction purposes. High or anomalous values of Poisson's ratio (or similarly P- and S-wave velocity ratio) depict a zone within the normally consolidated sediments that likely represents a coarse-grained layer, thus confirming earlier results from a number of boreholes drilled in the study area. Overall, the results presented further support to the previous hypothesis that the coarse-grained layer plays a major role in the formation and creation of quick-clay landslides in the study area. Additionally, an attempt to model the distribution of potential quick clays along one of the seismic profiles is performed through a combination of the modelled geophysical properties and soil textures. This study illustrates the potential of seismic methods, and how the integration of multiple geophysical properties and different data handling strategies can help to accurately characterize regions susceptible to quick-clay landslides.

Quick-clay landslides are important geohazards in Sweden, Norway and Canada. While they have been studied using various geotechnical and geophysical methods, only a handful of seismic surveys have been reported for their studies. Here, we reprocess active-source seismic data from a quick-clay landslide site in southwest Sweden to complement earlier studies of reflection imaging and first-break traveltime tomography with surface-wave dispersion analysis. Results suggest extremely low shear-wave velocities, even as low as 60–100 m/s. From a geotechnical perspective, this implies that the region classifies as a high-risk zone for landslides and construction purposes. High or anomalous values of Poisson's ratio (or similarly P- and S-wave velocity ratio) depict a zone within the normally consolidated sediments that likely represents a coarse-grained layer, thus confirming earlier results from a number of boreholes drilled in the study area. Overall, the results presented further support to the previous hypothesis that the coarse-grained layer plays a major role in the formation and creation of quick-clay landslides in the study area. Additionally, an attempt to model the distribution of potential quick clays along one of the seismic profiles is performed through a combination of the modelled geophysical properties and soil textures. This study illustrates the potential of seismic methods, and how the integration of multiple geophysical properties and different data handling strategies can help to accurately characterize regions susceptible to quick-clay landslides.

Modern sensing systems such as distributed acoustic sensing (DAS) can produce massive quantities of geophysical data, often in remote locations. This presents significant challenges with regards to data storage and performing efficient analysis. To address this, we have designed and implemented efficient algorithms for two commonly utilized techniques in geophysical imaging: cross-correlations, and multichannel analysis of surface waves (MASW). Our cross-correlation algorithms operate directly in the wavelet domain on compressed data without requiring a reconstruction of the original signal, reducing memory costs and improving scalabiliy. Meanwhile, our MASW implementations make use of MPI parallelism and GPUs, and present a novel problem for the GPU.

We applied active-source seismic method for the interpretation of elastic parameters in tailings facilities which is essential for evaluating stability and seismic response. The methodology uses different analysis methods on the same dataset, i.e., conventional seismic refraction (SR) to determine compressional-wave velocity (Vₚ) and multichannel analysis of surface wave (MASW) to estimate shear-wave velocity (Vₛ). Seismic velocities in conjunction with tailings physics approach revealed interpretable data in terms of elastic parameters and hydrogeological conditions. The results determined the empirical linear relationships between Vₚ and Vₛ that are particular to an unconsolidated media such as tailings and showed that variability of hydrogeological conditions influences the elastic seismic response (Vₚ and Vₛ) and the elastic parameters. The analysis of the elastic parameters identified the state condition of the tailings at the time of the survey. The Bulk modulus K that relates the change in hydrostatic stress to the volumetric strain was predominant between 1.0−2.0 GPa. The Young’s modulus E in the tailings media was in the low range of 0.15−0.23 GPa. Poisson’s ratio values in all sections were in the upper limit in the range of 0.37−0.49, meaning that the tailings media is highly susceptible to transverse deformation under axial compression.

Quick-clay landslides are important geohazards in Sweden, Norway and Canada. While they have been studied using various geotechnical and geophysical methods, only a handful of seismic surveys have been reported for their studies. Here, we reprocess active-source seismic data from a quick-clay landslide site in southwest Sweden to complement earlier studies of reflection imaging and first-break traveltime tomography with surface-wave dispersion analysis. Results suggest extremely low shear-wave velocities, even as low as 60–100 m/s. From a geotechnical perspective, this implies that the region classifies as a high-risk zone for landslides and construction purposes. High or anomalous values of Poisson's ratio (or similarly P- and S-wave velocity ratio) depict a zone within the normally consolidated sediments that likely represents a coarse-grained layer, thus confirming earlier results from a number of boreholes drilled in the study area. Overall, the results presented further support to the previous hypothesis that the coarse-grained layer plays a major role in the formation and creation of quick-clay landslides in the study area. Additionally, an attempt to model the distribution of potential quick clays along one of the seismic profiles is performed through a combination of the modelled geophysical properties and soil textures. This study illustrates the potential of seismic methods, and how the integration of multiple geophysical properties and different data handling strategies can help to accurately characterize regions susceptible to quick-clay landslides.

Non-destructive testing (NDT) plays an important role in the engineering, construction, and geophysical fields. The application of NDT in civil engineering is broad from quality control, structural health monitoring of infrastructure, geophysical and geotechnical field investigation and material characterization to detection of underground anomaly, among others. One of the frequently used NDT techniques for the characterization of geomaterials is based on the propagation of stress waves generated by an excitation source. However, the existing signal interpretation methods still predominantly rely on empirical relations or subjective judgements that are insufficient for the characterization of multiphase complex geomaterials. This research aims to develop novel physics-based signal interpretation methods to characterize physical and mechanical properties of multiphase geomaterials in both field and laboratory investigation scales. Several hybrid inverse and poromechanical models are developed to characterize dry, saturated, and frozen geomaterials subject to stress waves. First, a highly-efficient semi-analytical elastodynamic forward solver was proposed for the Multichannel Analysis of Surface Waves using the spectral element technique to determine effectively and efficiently the soil stratigraphy as well as soil properties. Next, a coupled piezoelectric and solid mechanics model is proposed to study the real response of the bender element (BE) and its interaction with soil samples in the BE test. A comprehensive laboratory investigation is also performed to better understand the response of the BEs inside different soil types. Then, a two-phase poromechanics-based signal interpretation model is developed for laboratory-scale ultrasonic testing to determine the physical and mechanical properties of saturated soil samples based on the distribution of stress waves. Subsequently, a three-phase poromechanical transfer function model is developed using the spectral eleme

This thesis presents the investigation results of interpreting hydrogeological and elastic properties in tailings storage facilities within the framework of hydrogeophysics. In this research, two geophysical methods were used for data acquisition: Seismic refraction (SR) and Electrical resistivity imaging (ERI). The application of seismic refraction (SR) and multichannel analysis of surface waves (MASW) was to obtain seismic velocity models (i.e., Vp and Vs), whereas electrical resistivity imaging (ERI) was applied to obtain cross-section models with bulk electrical resistivity data. In this approach, the outputs of the SR method set the geometric constraint for the inversion of the apparent electrical resistivity data in the ERI model. This research found that geophysical methods such as ERI and SR can retrieve high-resolution data from the subsurface of tailings facilities mapping the structure, the phreatic line, the dynamics of water, and detecting changes associated with the electrical resistivity response of the tailings media. The thesis also describes the methods and workflow for establishing dependencies between the geophysical signature (i.e., compressional and shear wave velocity models, electrical resistivity models) and the physical and water-related properties of the tailings media. The dependences in the form of empirical equations are key for filling the gap of theoretical deductions. Furthermore, this thesis contributes to the research field through a unified workflow for integrating petrophysical and ‘rock’ physics principles in the interpretation of geophysical data in tailings facilities. The interpretation describes and estimates quantitatively the state condition of the tailings subsurface in terms of hydrogeological (i.e., water saturation, water content, porosity) and elastic properties., Tiivistelmä Tämä väitöskirjatutkimus kuuluu hydrogeofysiikan piiriin, ja siinä tutkittiin rikastushiekan hydrogeologisia ja elastisia ominaisuuksia. Rikastushiekka-altaiden (Brukungan kaivos Etelä-Australiassa ja Pyhäsalmen kaivos Suomessa) hydrogeofysikaalisia ominaisuuksia tutkittiin kahdella eri geofysikaalisella menetelmällä; seismisellä taittumisluotauksella (Seismic refraction, SR) ja sähköisellä maavastusmenetelmällä (Electrical Resistivity imaging, ERI). Seismisen taittumisluotauksen (SR) ja pinta-aaltojen MASW-analyysin avulla pyrittiin laatimaan tutkimuskohteina olleiden rikastushiekka-altaiden seismiset nopeusmallit (ts. Vp ja Vs), kun taas rikastushiekka-altaiden poikkileikkausmallien laatimiseen käytettiin maavastusmittausaineiston inversiota. Väitöskirjassa toteutetulla lähestymistavalla SR-menetelmän avulla saatiin geometriset reunaehdot näennäiselle inversiolle ERI-mallissa. Tutkimuksessa havaittiin, että geofysikaalisilla menetelmillä, kuten ERI- ja SR-menetelmillä, voidaan saada resoluutioltaan tarkkaa numeerista tietoa rikastushiekka-altaiden tilasta, ja niiden avulla voidaan kartoittaa muun muassa rikastushiekka-altaiden rakennetta, freaattisen pinnan korkeutta, rikastushiekka-altaiden veden dynamiikkaa. Tutkimuksessa havaittiin, että geofysikaalisilla menetelmillä, kuten ERI- ja SR-menetelmillä, voidaan saada resoluutioltaan tarkkaa numeerista tietoa rikastushiekka-altaiden tilasta, ja niiden avulla voidaan kartoittaa muun muassa rikastushiekka-altaiden rakennetta, freaattisen pinnan korkeutta, rikastushiekka-altaiden veden dynamiikkaa. Empiiristen yhtälöiden muodossa olevien riippuvuussuhteiden selvittäminen on keskeistä, jotta teoreettista lähestymistapaa voidaan soveltaa rikastushiekka-altaiden kokonaisvaltaisessa hallinnassa. Väitöskirjassa kuvataan myös menetelmät ja työvuo, joilla määritetään petrofysikaalisten ominaisuuksien (ts. seismisten aaltojen nopeuden ja sähköjohtavuuden) ja rikastusallasmateriaalien geoteknisten ja veteen liittyvi

The main objectives of this research were to determine the seismic demand as well as to define the seismic microzonation in the urban sector of the city of Leon, this sector has about 173,866 inhabitants, this is the number of direct beneficiaries with the information produced in this research. In this research we used environmental vibration measurement (MHVSR), as well as surface wave measurement with the MASW active method. The empirical transfer functions(ETF) showed that the soils in the area vibrate with three modes, which vary their vibration period between the values To1=0.049 to 0.160 s, To2=0.161 to0.330 s and To3=0.331 to 0.969 s. In addition, based on the results of Vs30 and the RNC-07 the soils in the area can be classified as firm soils or moderately soft soil or as type II and III, respectively. The results of this research will be used to strengthen disaster mitigation against earthquakes in this city by being included in the Nicaraguan national construction regulations., Los objetivos principales de esta investigación fueron determinar la demanda sísmica así como definir la microzonificación sísmica en el sector urbano de la ciudad de León, este sector tiene alrededor de173,866 Habitantes, este es el número de beneficiados directos con la información producida en esta investigación. En esta investigación utilizamos medición de vibración ambiental (MHVSR), así como medición de ondas superficiales con el método activo MASW. Las funciones de transferencia empíricas(FTE) mostraron que los suelos del área vibran con tres modos, los cuales varían su periodo de vibración entre los valores To1=0.049 a 0.160 s, To2=0.161 a0.330 s y To3=0.331 a 0.969 s. Además, basado en los resultados de Vs30 y en el RNC-07 los suelos del área pueden clasificarse como suelos firmes o suelo moderadamente blando o como tipo II y III, respectivamente. Los resultados de esta investigación serán utilizados con fines de fortalecer la mitigación de desastres contra terremotos en esta ciudad al ser incluidos en el reglamento nacional de construcción nicaragüense.

The main objectives of this research were to determine the seismic demand as well as to define the seismic microzonation in the urban sector of the city of Leon, this sector has about 173,866 inhabitants, this is the number of direct beneficiaries with the information produced in this research. In this research we used environmental vibration measurement (MHVSR), as well as surface wave measurement with the MASW active method. The empirical transfer functions(ETF) showed that the soils in the area vibrate with three modes, which vary their vibration period between the values To1=0.049 to 0.160 s, To2=0.161 to0.330 s and To3=0.331 to 0.969 s. In addition, based on the results of Vs30 and the RNC-07 the soils in the area can be classified as firm soils or moderately soft soil or as type II and III, respectively. The results of this research will be used to strengthen disaster mitigation against earthquakes in this city by being included in the Nicaraguan national construction regulations., Los objetivos principales de esta investigación fueron determinar la demanda sísmica así como definir la microzonificación sísmica en el sector urbano de la ciudad de León, este sector tiene alrededor de173,866 Habitantes, este es el número de beneficiados directos con la información producida en esta investigación. En esta investigación utilizamos medición de vibración ambiental (MHVSR), así como medición de ondas superficiales con el método activo MASW. Las funciones de transferencia empíricas(FTE) mostraron que los suelos del área vibran con tres modos, los cuales varían su periodo de vibración entre los valores To1=0.049 a 0.160 s, To2=0.161 a0.330 s y To3=0.331 a 0.969 s. Además, basado en los resultados de Vs30 y en el RNC-07 los suelos del área pueden clasificarse como suelos firmes o suelo moderadamente blando o como tipo II y III, respectivamente. Los resultados de esta investigación serán utilizados con fines de fortalecer la mitigación de desastres contra terremotos en esta ciudad al ser incluidos en el reglamento nacional de construcción nicaragüense.

The main objectives of this research were to determine the seismic demand as well as to define the seismic microzonation in the urban sector of the city of Leon, this sector has about 173,866 inhabitants, this is the number of direct beneficiaries with the information produced in this research. In this research we used environmental vibration measurement (MHVSR), as well as surface wave measurement with the MASW active method. The empirical transfer functions(ETF) showed that the soils in the area vibrate with three modes, which vary their vibration period between the values To1=0.049 to 0.160 s, To2=0.161 to0.330 s and To3=0.331 to 0.969 s. In addition, based on the results of Vs30 and the RNC-07 the soils in the area can be classified as firm soils or moderately soft soil or as type II and III, respectively. The results of this research will be used to strengthen disaster mitigation against earthquakes in this city by being included in the Nicaraguan national construction regulations., Los objetivos principales de esta investigación fueron determinar la demanda sísmica así como definir la microzonificación sísmica en el sector urbano de la ciudad de León, este sector tiene alrededor de173,866 Habitantes, este es el número de beneficiados directos con la información producida en esta investigación. En esta investigación utilizamos medición de vibración ambiental (MHVSR), así como medición de ondas superficiales con el método activo MASW. Las funciones de transferencia empíricas(FTE) mostraron que los suelos del área vibran con tres modos, los cuales varían su periodo de vibración entre los valores To1=0.049 a 0.160 s, To2=0.161 a0.330 s y To3=0.331 a 0.969 s. Además, basado en los resultados de Vs30 y en el RNC-07 los suelos del área pueden clasificarse como suelos firmes o suelo moderadamente blando o como tipo II y III, respectivamente. Los resultados de esta investigación serán utilizados con fines de fortalecer la mitigación de desastres contra terremotos en esta ciudad al ser incluidos en el reglamento nacional de construcción nicaragüense.

Quick-clay landslides are important geohazards in Sweden, Norway and Canada. While they have been studied using various geotechnical and geophysical methods, only a handful of seismic surveys have been reported for their studies. Here, we reprocess active-source seismic data from a quick-clay landslide site in southwest Sweden to complement earlier studies of reflection imaging and first-break traveltime tomography with surface-wave dispersion analysis. Results suggest extremely low shear-wave velocities, even as low as 60–100 m/s. From a geotechnical perspective, this implies that the region classifies as a high-risk zone for landslides and construction purposes. High or anomalous values of Poisson's ratio (or similarly P- and S-wave velocity ratio) depict a zone within the normally consolidated sediments that likely represents a coarse-grained layer, thus confirming earlier results from a number of boreholes drilled in the study area. Overall, the results presented further support to the previous hypothesis that the coarse-grained layer plays a major role in the formation and creation of quick-clay landslides in the study area. Additionally, an attempt to model the distribution of potential quick clays along one of the seismic profiles is performed through a combination of the modelled geophysical properties and soil textures. This study illustrates the potential of seismic methods, and how the integration of multiple geophysical properties and different data handling strategies can help to accurately characterize regions susceptible to quick-clay landslides.

La estructura profunda de la falla de Alhama de Murcia (AMF) ha sido caracterizada mediante el análisis de ondas superficiales identificados en datos de reflexión sísmica superficial de alta resolución. El análisis multicanal de ondas de superficie (MASW) es usado para desentrañar un modelo 2D de Vs y para obtener imágenes de la geometría del sistema de fallas en profundidad. El área de estudio incluye segmentos de la AMF ubicados en el área de La Salud. Se han utilizado dos enfoques para lograr modelos de velocidad bien restringidos de la zona de falla. Por un lado, se han limpiado los datos utilizado un flujo de procesado convencional diseñado para aumentar su ratio de señal/ruido. Por el otro, se ha usado el enfoque de Occam para invertir las curvas de dispersión de ondas de superficie digitalizadas. Los perfiles 1D de profundidad de las Vs fueron estimados en los dominios de disparo y de CDP. Se obtuvieron modelos de velocidad-profundidad 2D relativamente bien resueltos mediante la interpolación de las funciones de velocidad-profundidad 1D. Estos modelos de velocidad 2D ayudan a restringir en profundidad la geometría de la zona de falla hasta los 100 m que se caracteriza por una anomalía de baja velocidad relativamente amplia que se correlaciona en la superficie con la expresión de la falla., The deep structure of the Alhama de Murcia Fault (AMF) is characterized by means of the analysis of surface waves identified in shallow high resolution seismic reflection data. Multichannel analysis of surface waves (MASW) is used to unravel the 2-D S-wave velocity model and image the depth geometry of the fault system. The study area includes segments of the fault located in La Salud area. Two approaches have been used to achieve a well constrained velocity model in the AMF fault zone. Conventional seismic reflection processing work flow has been used to clean the seismic data and increase its S/N ratio. Occam's approach has been used to invert the digitized surface wave dispersion curves. 1D shear wave velocity-depth profiles were estimated in shot and CDP domains. Relatively well resolved 2D velocity-depth models were obtained by composite of the 1D Velocity-depth functions. These composite 2D-velocity models are able to constrain the depth geometry of the fault zone up to 100 m depth. The fault zone is indicated by a relatively broad low velocity anomaly that correlates with the fault’s surface expression.

Non-destructive testing (NDT) plays an important role in the engineering, construction, and geophysical fields. The application of NDT in civil engineering is broad from quality control, structural health monitoring of infrastructure, geophysical and geotechnical field investigation and material characterization to detection of underground anomaly, among others. One of the frequently used NDT techniques for the characterization of geomaterials is based on the propagation of stress waves generated by an excitation source. However, the existing signal interpretation methods still predominantly rely on empirical relations or subjective judgements that are insufficient for the characterization of multiphase complex geomaterials. This research aims to develop novel physics-based signal interpretation methods to characterize physical and mechanical properties of multiphase geomaterials in both field and laboratory investigation scales. Several hybrid inverse and poromechanical models are developed to characterize dry, saturated, and frozen geomaterials subject to stress waves. First, a highly-efficient semi-analytical elastodynamic forward solver was proposed for the Multichannel Analysis of Surface Waves using the spectral element technique to determine effectively and efficiently the soil stratigraphy as well as soil properties. Next, a coupled piezoelectric and solid mechanics model is proposed to study the real response of the bender element (BE) and its interaction with soil samples in the BE test. A comprehensive laboratory investigation is also performed to better understand the response of the BEs inside different soil types. Then, a two-phase poromechanics-based signal interpretation model is developed for laboratory-scale ultrasonic testing to determine the physical and mechanical properties of saturated soil samples based on the distribution of stress waves. Subsequently, a three-phase poromechanical transfer function model is developed using the spectral eleme

Geotechnical site characterization is typically accomplished through the use of drilling programs, frequently employing numerous bore holes to characterize the subsurface at discrete locations. While usually sufficient, this method of investigation can be problematic for highly heterogeneous subsurface conditions, as the approach generally lacks lateral resolution. This deficiency in horizontal resolution can be particularly damaging in the Winnipeg and surrounding area, as the near-surface stratigraphy includes a thick sequence of glaciolacustrine clay that often contains sporadic collections of glacial debris. Such collections, if left undetected, can potentially result in engineering project delays and associated cost overruns. To overcome such problems, and provide an alternate method of subsurface characterization, the feasibility of using both electrical resistivity tomography (ERT) and multi-channel analysis of surface waves (MASW) geophysical methods for the detection of buried glacial debris was investigated. To assess the suitability of each method, testing was completed in two main stages, with both numerical modeling and field analysis conducted. During the initial modeling stage, results indicated that both methods were capable of detecting larger debris accretions (lateral extent > 8m), with each recovering a response for such objects at depths upwards of 6 m. Results from subsequent field testing were similarly successful, with each method detecting a response from buried debris of various size and depth. ERT data was found to be particularly effective, with data from field testing accurately recovering the lateral position of numerous discrete objects. In comparison, while successful at detecting an anomalous response, the MASW method was unable to image singular objects, with the signature from individual features being averaged into a single layer. However, secondary backscattering analysis (BSA) completed using the same seismic data proved success

Geotechnical site characterization is typically accomplished through the use of drilling programs, frequently employing numerous bore holes to characterize the subsurface at discrete locations. While usually sufficient, this method of investigation can be problematic for highly heterogeneous subsurface conditions, as the approach generally lacks lateral resolution. This deficiency in horizontal resolution can be particularly damaging in the Winnipeg and surrounding area, as the near-surface stratigraphy includes a thick sequence of glaciolacustrine clay that often contains sporadic collections of glacial debris. Such collections, if left undetected, can potentially result in engineering project delays and associated cost overruns. To overcome such problems, and provide an alternate method of subsurface characterization, the feasibility of using both electrical resistivity tomography (ERT) and multi-channel analysis of surface waves (MASW) geophysical methods for the detection of buried glacial debris was investigated. To assess the suitability of each method, testing was completed in two main stages, with both numerical modeling and field analysis conducted. During the initial modeling stage, results indicated that both methods were capable of detecting larger debris accretions (lateral extent > 8m), with each recovering a response for such objects at depths upwards of 6 m. Results from subsequent field testing were similarly successful, with each method detecting a response from buried debris of various size and depth. ERT data was found to be particularly effective, with data from field testing accurately recovering the lateral position of numerous discrete objects. In comparison, while successful at detecting an anomalous response, the MASW method was unable to image singular objects, with the signature from individual features being averaged into a single layer. However, secondary backscattering analysis (BSA) completed using the same seismic data proved success

Geotechnical site characterization is typically accomplished through the use of drilling programs, frequently employing numerous bore holes to characterize the subsurface at discrete locations. While usually sufficient, this method of investigation can be problematic for highly heterogeneous subsurface conditions, as the approach generally lacks lateral resolution. This deficiency in horizontal resolution can be particularly damaging in the Winnipeg and surrounding area, as the near-surface stratigraphy includes a thick sequence of glaciolacustrine clay that often contains sporadic collections of glacial debris. Such collections, if left undetected, can potentially result in engineering project delays and associated cost overruns. To overcome such problems, and provide an alternate method of subsurface characterization, the feasibility of using both electrical resistivity tomography (ERT) and multi-channel analysis of surface waves (MASW) geophysical methods for the detection of buried glacial debris was investigated. To assess the suitability of each method, testing was completed in two main stages, with both numerical modeling and field analysis conducted. During the initial modeling stage, results indicated that both methods were capable of detecting larger debris accretions (lateral extent > 8m), with each recovering a response for such objects at depths upwards of 6 m. Results from subsequent field testing were similarly successful, with each method detecting a response from buried debris of various size and depth. ERT data was found to be particularly effective, with data from field testing accurately recovering the lateral position of numerous discrete objects. In comparison, while successful at detecting an anomalous response, the MASW method was unable to image singular objects, with the signature from individual features being averaged into a single layer. However, secondary backscattering analysis (BSA) completed using the same seismic data proved success

Geotechnical site characterization is typically accomplished through the use of drilling programs, frequently employing numerous bore holes to characterize the subsurface at discrete locations. While usually sufficient, this method of investigation can be problematic for highly heterogeneous subsurface conditions, as the approach generally lacks lateral resolution. This deficiency in horizontal resolution can be particularly damaging in the Winnipeg and surrounding area, as the near-surface stratigraphy includes a thick sequence of glaciolacustrine clay that often contains sporadic collections of glacial debris. Such collections, if left undetected, can potentially result in engineering project delays and associated cost overruns. To overcome such problems, and provide an alternate method of subsurface characterization, the feasibility of using both electrical resistivity tomography (ERT) and multi-channel analysis of surface waves (MASW) geophysical methods for the detection of buried glacial debris was investigated. To assess the suitability of each method, testing was completed in two main stages, with both numerical modeling and field analysis conducted. During the initial modeling stage, results indicated that both methods were capable of detecting larger debris accretions (lateral extent > 8m), with each recovering a response for such objects at depths upwards of 6 m. Results from subsequent field testing were similarly successful, with each method detecting a response from buried debris of various size and depth. ERT data was found to be particularly effective, with data from field testing accurately recovering the lateral position of numerous discrete objects. In comparison, while successful at detecting an anomalous response, the MASW method was unable to image singular objects, with the signature from individual features being averaged into a single layer. However, secondary backscattering analysis (BSA) completed using the same seismic data proved success

The seismic hazard and risk analysis for the onshore Groningen gas field requires information about local soil properties, in particular shear-wave velocity (VS). A fieldwork campaign was conducted at 18 surface accelerograph stations of the monitoring network. The subsurface in the region consists of unconsolidated sediments and is heterogeneous in composition and properties. A range of different methods was applied to acquire in situ VS values to a target depth of at least 30 m. The techniques include seismic cone penetration tests (SCPT) with varying source offsets, multichannel analysis of surface waves (MASW) on Rayleigh waves with different processing approaches, microtremor array, cross-hole tomography and suspension P-S logging. The offset SCPT, cross-hole tomography and common midpoint cross-correlation (CMPcc) processing of MASW data all revealed lateral variations on length scales of several to tens of metres in this geological setting. SCPTs resulted in very detailed VS profiles with depth, but represent point measurements in a heterogeneous environment. The MASW results represent VS information on a larger spatial scale and smooth some of the heterogeneity encountered at the sites. The combination of MASW and SCPT proved to be a powerful and cost-effective approach in determining representative VS profiles at the accelerograph station sites. The measured VS profiles correspond well with the modelled profiles and they significantly enhance the ground motion model derivation. The similarity between the theoretical transfer function from the VS profile and the observed amplification from vertical array stations is also excellent.

Se realizarán dos campañas de toma de datos con el equipo de MASW y se determinarán a partir de los resultados obtenidos los distintos escenarios de movimiento sísmico del terreno.

Creating accurate engineering models for predicting the response of large structures often requires geotechnical modelling of soil behaviour. Soil material damping is an important input parameter for modelling the structural response and energy dissipation, especially for embedded and lightly damped structures, as in particular for offshore wind turbines. Non-invasive in-situ measurements like the multichannel analysis of surface waves, offer cost-effective solutions and estimations over a wider volume of soil. This research aims to demonstrate that MASW technique can be used to generate a reliable in-situ estimation of the soil damping in marine environments in the depth range of 0-30m. A unique and high-quality dataset has been made available through a collaboration with the Norwegian Geotechnical Institute (NGI). Shear wave data are rarely available for offshore site investigations and have not been used before for a damping inversion from real surface waves measurements. Moreover, also the horizontal soil response was recorded in this measurements which allow for reducing the uncertainties of the results obtained by using the Scholte wave model. Therefore, two forward waves models are implemented in Matlab to reproduce both the in-line and cross-line measurements. A reliable shear wave velocity profile is derived via the stiffness inversion method, after which the damping inversion is performed. A modal damping inversion method is developed and it uses a novel modified random search algorithm in order to estimate the material damping profile over depth. The attenuation coefficient is chosen as the reference parameter for the damping inversion and the misfit function for the damping inversion is defined as the normalized difference per frequency of the attenuation curves. The measured attenuation coefficient is extracted based on a modified half-power bandwidth method. The modelled attenuation curve is retrieved as the imaginary part of the complex wavenu

Creating accurate engineering models for predicting the response of large structures often requires geotechnical modelling of soil behaviour. Soil material damping is an important input parameter for modelling the structural response and energy dissipation, especially for embedded and lightly damped structures, as in particular for offshore wind turbines. Non-invasive in-situ measurements like the multichannel analysis of surface waves, offer cost-effective solutions and estimations over a wider volume of soil. This research aims to demonstrate that MASW technique can be used to generate a reliable in-situ estimation of the soil damping in marine environments in the depth range of 0-30m. A unique and high-quality dataset has been made available through a collaboration with the Norwegian Geotechnical Institute (NGI). Shear wave data are rarely available for offshore site investigations and have not been used before for a damping inversion from real surface waves measurements. Moreover, also the horizontal soil response was recorded in this measurements which allow for reducing the uncertainties of the results obtained by using the Scholte wave model. Therefore, two forward waves models are implemented in Matlab to reproduce both the in-line and cross-line measurements. A reliable shear wave velocity profile is derived via the stiffness inversion method, after which the damping inversion is performed. A modal damping inversion method is developed and it uses a novel modified random search algorithm in order to estimate the material damping profile over depth. The attenuation coefficient is chosen as the reference parameter for the damping inversion and the misfit function for the damping inversion is defined as the normalized difference per frequency of the attenuation curves. The measured attenuation coefficient is extracted based on a modified half-power bandwidth method. The modelled attenuation curve is retrieved as the imaginary part of the complex wavenu

The seismic hazard and risk analysis for the onshore Groningen gas field requires information about local soil properties, in particular shear-wave velocity (V (S)). A fieldwork campaign was conducted at 18 surface accelerograph stations of the monitoring network. The subsurface in the region consists of unconsolidated sediments and is heterogeneous in composition and properties. A range of different methods was applied to acquire in situ V (S) values to a target depth of at least 30 m. The techniques include seismic cone penetration tests (SCPT) with varying source offsets, multichannel analysis of surface waves (MASW) on Rayleigh waves with different processing approaches, microtremor array, cross-hole tomography and suspension P-S logging. The offset SCPT, cross-hole tomography and common midpoint cross-correlation (CMPcc) processing of MASW data all revealed lateral variations on length scales of several to tens of metres in this geological setting. SCPTs resulted in very detailed V (S) profiles with depth, but represent point measurements in a heterogeneous environment. The MASW results represent V (S) information on a larger spatial scale and smooth some of the heterogeneity encountered at the sites. The combination of MASW and SCPT proved to be a powerful and cost-effective approach in determining representative V (S) profiles at the accelerograph station sites. The measured V (S) profiles correspond well with the modelled profiles and they significantly enhance the ground motion model derivation. The similarity between the theoretical transfer function from the V (S) profile and the observed amplification from vertical array stations is also excellent.

This study reviews the correlation between the experimental Rayleigh dispersion curve and the Vp & Vs ground model versus depth. Six samples of stations A , B , C , D ,  E  and  F  were used in the experiment.The geophone spacing used was set 1 m and total length of each line was 23 m. The result shows positive significance (best fit) of R2 that ranges from 0.80 to 0.90. The fk (frequency-wave number method) dispersion curves analysis confirmed that the soil structure investigated is divided into three zones: (1) Unsaturated soil zone (clay soil), in which the layer is dominated by soil with typically alluvial clayey silt and sand. The Vp ranges from 240 m/s to 255 m/s at a depth of 2 to 8 m. (2) The intermediate zone (stiff soil), in which the layer is dominated by sand, silt, clayey sand, sandy clay and clay of low plasticity. This structure is interpreted as partially saturated soil zone, the soil is typically very dense. It contains soft rock typically fill with cobble, sand, slight gravel and highly weathered at depth of 18 to 30 m with Vp of  255 to 300 m/s. (3) Saturated soil zone at a depth of  8 to 18 m with Vp of 300 to 390 m/s. There is a very good agreement between wave-number (k) and phase velocity (Vw)  produced. Both the two parameters shows similar pattern in the topsoil and subsurface layer, which constitute boundary field of soil structure. Moreover, relationship between phase velocity versus wave-length shows best fit of model from inversion with measured value (observed) in  implementation of the boundary and depth of each layer.

This study reviews the correlation between the experimental Rayleigh dispersion curve and the Vp & Vs ground model versus depth. Six samples of stations A , B , C , D ,  E  and  F  were used in the experiment.The geophone spacing used was set 1 m and total length of each line was 23 m. The result shows positive significance (best fit) of R2 that ranges from 0.80 to 0.90. The fk (frequency-wave number method) dispersion curves analysis confirmed that the soil structure investigated is divided into three zones: (1) Unsaturated soil zone (clay soil), in which the layer is dominated by soil with typically alluvial clayey silt and sand. The Vp ranges from 240 m/s to 255 m/s at a depth of 2 to 8 m. (2) The intermediate zone (stiff soil), in which the layer is dominated by sand, silt, clayey sand, sandy clay and clay of low plasticity. This structure is interpreted as partially saturated soil zone, the soil is typically very dense. It contains soft rock typically fill with cobble, sand, slight gravel and highly weathered at depth of 18 to 30 m with Vp of  255 to 300 m/s. (3) Saturated soil zone at a depth of  8 to 18 m with Vp of 300 to 390 m/s. There is a very good agreement between wave-number (k) and phase velocity (Vw)  produced. Both the two parameters shows similar pattern in the topsoil and subsurface layer, which constitute boundary field of soil structure. Moreover, relationship between phase velocity versus wave-length shows best fit of model from inversion with measured value (observed) in  implementation of the boundary and depth of each layer.

Mapping surficial and subsurface conditions play an important role in analysis and design of geotechnical structures and facilities. Spatial distribution of depth to soil-bedrock interface has a prime significance in developing input ground motion at the surface and estimating damage potential of an earthquake. This paper deals with the evaluation of spatial variability of soil-bedrock interface in Chennai, south India using Multichannel Analysis of Surface Wave (MASW) test and Standard Penetration Test (SPT) data. The MASW tests have been carried out at selected locations in Chennai city using 24 channel Geode and shear-wave velocity profiles are developed. Based on the MASW test results, a shear wave velocity (Vs) of around 300 m/s is obtained for weathered/soft rock, and a value of 700 m/s for hard rock in the present study. Depths corresponding to these velocity ranges are identified to estimate the position of soil-bedrock interface in the study area consisting of IIT Madras campus and its surrounding area. In addition, nearly 85 borelogs have been used to identify the main soil types and variation in depths to bedrock in the study area. A comprehensive geo-database containing all subsoil information has been designed to create three-dimensional borelog information and depth to bedrock interface. The spatial variability of depth to soil-bedrock interface at the locations where field measurements are not available has been mapped using spatial interpolation technique called kriging. The developed bedrock map indicates that the depth to soil-rock interface varies from 2 to 18 m in the study area. The evaluated depths to soil-bedrock interfaces have been compared and validated with the subsurface profile information obtained from a few selected borehole data and MASW test results. Further, the available SPT data can effectively be utilized for developing shear wave velocity distribution maps at different depths along the soil profile using the correlation between

Mapping surficial and subsurface conditions play an important role in analysis and design of geotechnical structures and facilities. Spatial distribution of depth to soil-bedrock interface has a prime significance in developing input ground motion at the surface and estimating damage potential of an earthquake. This paper deals with the evaluation of spatial variability of soil-bedrock interface in Chennai, south India using Multichannel Analysis of Surface Wave (MASW) test and Standard Penetration Test (SPT) data. The MASW tests have been carried out at selected locations in Chennai city using 24 channel Geode and shear-wave velocity profiles are developed. Based on the MASW test results, a shear wave velocity (Vs) of around 300 m/s is obtained for weathered/soft rock, and a value of 700 m/s for hard rock in the present study. Depths corresponding to these velocity ranges are identified to estimate the position of soil-bedrock interface in the study area consisting of IIT Madras campus and its surrounding area. In addition, nearly 85 borelogs have been used to identify the main soil types and variation in depths to bedrock in the study area. A comprehensive geo-database containing all subsoil information has been designed to create three-dimensional borelog information and depth to bedrock interface. The spatial variability of depth to soil-bedrock interface at the locations where field measurements are not available has been mapped using spatial interpolation technique called kriging. The developed bedrock map indicates that the depth to soil-rock interface varies from 2 to 18 m in the study area. The evaluated depths to soil-bedrock interfaces have been compared and validated with the subsurface profile information obtained from a few selected borehole data and MASW test results. Further, the available SPT data can effectively be utilized for developing shear wave velocity distribution maps at different depths along the soil profile using the correlation between

A Master of Science thesis in Civil Engineering by Niamatullah Haji Bismillah entitled, "Variation of Shear Wave Velocity with SPT-N Values in the City of Sharjah," submitted in June 2014. Thesis advisor is Dr. Zahid Khan. Available are both soft and hard copies of the thesis., Modern building codes require the evaluation of a shear wave velocity profile of the foundation soils for a dynamic analysis of structures and sites to occur. Wave velocities are typically evaluated by conducting laboratory and field tests. Due to the rapid pace of development in the UAE,consultants often rely on shear wave velocity (VS) obtained from correlations of shear wave velocity (VS) with N values from Standard Penetration Tests (SPT). Significant variationsin previous studies that predict wave velocities justifythis new study in order to develop correlations specific to the region and applicable to areas of similar geology. These variations can be attributed to factors such as biases in conducting field tests and shortcomings in seismic techniques. This study presents the correlations developed between wave velocity and N values for the city of Sharjah by performing seismic tests in various locations. The velocity profiles are evaluated by using vertical geophones that are traditionally used, as well as, horizontal geophones to evaluate their ability in calculating similar profiles. The analysis of surface waves for velocity evaluation is preferred due to its ability in delineating hidden layers of weaker velocities and for the better characterization of shallow depths from the generation of higher frequency phases. The benefits of using a seismic technique based on surface waves are presented and the results of the regression of VS-N pairs are compared with the findings of previous studies discussed here. The effect of using horizontal and vertical geophones on the results is evaluated in order to validate the theoretical basis of particle motion during the propagation of surface waves. The results indicate many previous models underestimate the wave velocity as function of N valuesas compared to the proposed model, especially at N values larger than 15. Most recent studies, however, tend to agree with the prediction model of this study;only one model sign, College of Engineering, Department of Civil Engineering

Inhaltszusammenfassung: In der Ingenieurgeologie sind Kenntnisse über die Verteilung von geotechnischen Parametern im oberflächennahen Untergrund von entscheidender Bedeutung. Neueste Entwicklungen im Bereich der Ingenieurgeophysik und von Direct-Push-Verfahren (DP) bieten umfangreiche technische Möglichkeiten für nichtinvasive bzw. In-situ-Parametrisierung. Es kommen unterschiedliche, eher grobe, geotechnische Standartuntersuchungs- und Analyseverfahren zum Einsatz, z.B. Bohrungen und Siebanalysen. Standardisierte Labormethoden und unterstützende Geländemessungen zur Bestimmung relevanter Bodeneigenschaften sowie zur Bodentypbestimmung können Homogenbereichen (Schichten) im Untergrund zugeordnet werden. Die standortabhängige Interpretation dieser Daten ist jedoch schwierig, da die natürlichen Eigenschaften am Standort (in situ) auf Grund der stark heterogenen Natur oberflächennaher Lockergesteine von den Laborbedingungen abweichen. An zwei Standorten (Löbnitz und Taucha) wurden umfangreiche Feldarbeiten durchgeführt. Als Repräsentanten typischer Baugrundsituationen in Mitteldeutschland, wurden hier die Elektr. Widerstandstomographie, Bodenradar, Refraktionsseismik, multichannel analysis of surface waves sowie eine mobile, DP-basierte seismische Laufzeittomographie getestet. Der kombinierte Einsatz gleicht Beschränkungen und Nachteile einzelner Verfahren aus, welche sich aus dem Kontrast bzw. der spezifischen Sensitivität gegenüber dem jeweilig gemessen physikalischen Parameter ergeben. Durch den Einsatz von DP-Systemen in der Entwicklung einer mobilen, seismischen Tomographie kann die Abhängigkeit zu stationär vorhandenen Bohrlöchern überwunden werden. Die abgeleiteten geotechnischen Parameter erlauben eine Unsicherheitsabschätzung, evaluiert durch hochauflösende Daten zusätzlich durchgeführter DP-Methoden. Ferner ermöglichen DP-basierte In-situ-Bodenfarbmessungen mittels Colorimetersonden eine stratigraphische Modelbildung. Bisher sind für solcherart hochaufgelöst

Inhaltszusammenfassung: In der Ingenieurgeologie sind Kenntnisse über die Verteilung von geotechnischen Parametern im oberflächennahen Untergrund von entscheidender Bedeutung. Neueste Entwicklungen im Bereich der Ingenieurgeophysik und von Direct-Push-Verfahren (DP) bieten umfangreiche technische Möglichkeiten für nichtinvasive bzw. In-situ-Parametrisierung. Es kommen unterschiedliche, eher grobe, geotechnische Standartuntersuchungs- und Analyseverfahren zum Einsatz, z.B. Bohrungen und Siebanalysen. Standardisierte Labormethoden und unterstützende Geländemessungen zur Bestimmung relevanter Bodeneigenschaften sowie zur Bodentypbestimmung können Homogenbereichen (Schichten) im Untergrund zugeordnet werden. Die standortabhängige Interpretation dieser Daten ist jedoch schwierig, da die natürlichen Eigenschaften am Standort (in situ) auf Grund der stark heterogenen Natur oberflächennaher Lockergesteine von den Laborbedingungen abweichen. An zwei Standorten (Löbnitz und Taucha) wurden umfangreiche Feldarbeiten durchgeführt. Als Repräsentanten typischer Baugrundsituationen in Mitteldeutschland, wurden hier die Elektr. Widerstandstomographie, Bodenradar, Refraktionsseismik, multichannel analysis of surface waves sowie eine mobile, DP-basierte seismische Laufzeittomographie getestet. Der kombinierte Einsatz gleicht Beschränkungen und Nachteile einzelner Verfahren aus, welche sich aus dem Kontrast bzw. der spezifischen Sensitivität gegenüber dem jeweilig gemessen physikalischen Parameter ergeben. Durch den Einsatz von DP-Systemen in der Entwicklung einer mobilen, seismischen Tomographie kann die Abhängigkeit zu stationär vorhandenen Bohrlöchern überwunden werden. Die abgeleiteten geotechnischen Parameter erlauben eine Unsicherheitsabschätzung, evaluiert durch hochauflösende Daten zusätzlich durchgeführter DP-Methoden. Ferner ermöglichen DP-basierte In-situ-Bodenfarbmessungen mittels Colorimetersonden eine stratigraphische Modelbildung. Bisher sind für solcherart hochaufgelöst

Using geophysical methods for the geomorphological characterization of subsurface features has numerous advantages over traditional exploration methods, because of their noninvasive and rapid nature. In this study, we compared the results of four geophysical methods with each other. We also discuss their possibilities and limitations in a geomorphological investigation. Electrical resistivity tomography (ERT), refraction seismic (RS), ground penetrating radar (GPR), and surface wave seismic (MASW) methods were applied at an abandoned meander in northern Saxony to map a predefined structure. By combining these methods, we were able to characterize and delineate subsurface features of the abandoned meander, including a point bar, a channel, and a cutbank. Core samples obtained from sonic drilling were used to validate the findings of both seismic methods. However, we found that electrical resistivity tomography and ground penetrating radar lacked penetration depth and could only be used to resolve shallower subsurface layers. The ERT, GPR, RS, and MASW can be used to gather images of subsurface structures. The MASW in particular provides supplementary information about the channel’s internal structure (with respect to lateral and vertical resolution). Besides fluvial–morphological features, we also detected inverse velocity structures within the channel. This allowed us to characterize the abandoned meander using information about its layer distribution and material composition. However, we were only able to characterize and delineate the subsurface features of the abandoned meander by combining all of the aforementioned methods.

Localement, les mouvements du sol en surface peuvent être amplifiés durant un séisme. Les plus grands déplacements se situent à la fréquence naturelle du sol. Son estimation est donc nécessaire pour caractériser l'effet de site. L'analyse du bruit ambiant permet de déterminer directement la fréquence fondamentale hors activité sismique et sans nuisance pour l'environnement. Plusieurs campagnes de bruit ambiant ont été réalisées entre 2006 et 2007 par la commission géologique du Canada sur le territoire québécois. Les résultats obtenus ont permis de tester la validité de la méthode et d'en étudier les différents paramètres d'analyses. Une campagne d'enregistrement de bruit ambiant a été effectuée en juin 2007 dans le cadre d'une étude de stabilité de pente. Elle a permis de mettre en évidence le rôle important de la topographie dans l'estimation de la fréquence de résonance. Malgré une différence de hauteur du dépôt en amont et en aval de la pente, les fréquences naturelles sont identiques. Afin de confirmer l'influence de la topographie sur l'estimation locale de la fréquence de résonance, les résultats de deux méthodes d'investigation ont été comparés. La méthode MASW (Modal Analysis of Surface Waves), développée à l'université de Sherbrooke, permet de déterminer le profil des vitesses de cisaillement en surface et ainsi la fréquence propre. La méthode de Nakamura propose d'étudier le rapport spectral des composantes horizontales et verticales du bruit ambiant. Ce rapport spectral présente un pic à la fréquence fondamentale. Cette étude démontre que la méthode des rapports spectraux donne une estimation de la fréquence naturelle d'un sol qui prend en compte l'ensemble du relief. Les données obtenues à partir de la méthode MASW, ont permis d'effectuer des simulations numériques avec des vitesses de cisaillement du sol et des topographies différentes. Plusieurs modèles ont été réalisés pour trois vitesses de cisaillement, avec deux pentes différentes et avec une vari

Localement, les mouvements du sol en surface peuvent être amplifiés durant un séisme. Les plus grands déplacements se situent à la fréquence naturelle du sol. Son estimation est donc nécessaire pour caractériser l'effet de site. L'analyse du bruit ambiant permet de déterminer directement la fréquence fondamentale hors activité sismique et sans nuisance pour l'environnement. Plusieurs campagnes de bruit ambiant ont été réalisées entre 2006 et 2007 par la commission géologique du Canada sur le territoire québécois. Les résultats obtenus ont permis de tester la validité de la méthode et d'en étudier les différents paramètres d'analyses. Une campagne d'enregistrement de bruit ambiant a été effectuée en juin 2007 dans le cadre d'une étude de stabilité de pente. Elle a permis de mettre en évidence le rôle important de la topographie dans l'estimation de la fréquence de résonance. Malgré une différence de hauteur du dépôt en amont et en aval de la pente, les fréquences naturelles sont identiques. Afin de confirmer l'influence de la topographie sur l'estimation locale de la fréquence de résonance, les résultats de deux méthodes d'investigation ont été comparés. La méthode MASW (Modal Analysis of Surface Waves), développée à l'université de Sherbrooke, permet de déterminer le profil des vitesses de cisaillement en surface et ainsi la fréquence propre. La méthode de Nakamura propose d'étudier le rapport spectral des composantes horizontales et verticales du bruit ambiant. Ce rapport spectral présente un pic à la fréquence fondamentale. Cette étude démontre que la méthode des rapports spectraux donne une estimation de la fréquence naturelle d'un sol qui prend en compte l'ensemble du relief. Les données obtenues à partir de la méthode MASW, ont permis d'effectuer des simulations numériques avec des vitesses de cisaillement du sol et des topographies différentes. Plusieurs modèles ont été réalisés pour trois vitesses de cisaillement, avec deux pentes différentes et avec une vari

As a continuation of a seismic experiment to test the capability of a newly developed 3C(three component) MEMS-based (microelectro-mechanical system) seismic landstreamer fordelineating an esker core (porous glacial sediments), depth to water table and bedrock insouthwestern Finland, additional analysis of the same dataset was performed. The seismic sourceused was a 500-kg vertical impact drophammer. We report results from one of the horizontalcomponents of the landstreamer data, the transverse (SH-wave) component. In addition to this,we complement the interpretation conducted previously on P-wave stacked section with surfacewavederived shear-wave velocities and Vp/Vs ratios along the entire profile.Although the seismic source used is of vertical-type nature, peculiarly, the data inspectionshowed clear bedrock reflection on the SH-wave component. This observation led us toscrutinize the transverse component data through side-by-side inspection of the shot records onall the three components and particle motion (hodograms) analysis to confirm the pure shearnature of the reflection. Using the apparent moveout velocity of the reflection, as well as knowndepth to bedrock based on drilling, we employed finite-difference synthetic modelling to furtherverify the nature of the reflection. Compared to the P-wave seismic section, bedrock is moreaccurately delineated on the SH-wave section. Some structures connected to the MUKH(morphologically undetectable kettle hole) imaged on the P-wave results are also notable on theSH-wave section, and particularly on the surface-wave derived shear-wave velocity model. Ourresults indicate that the SH-wave energy is generated at the source location itself. This study isencouraging and illustrates why multicomponent seismic data should be acquired and analyzedfor near-surface applications.

DTRT13-G-UTC36, The purpose of this research is to establish a recommended procedure for performing multichannel analysis of surface waves (MASW) on pavements as well as evaluating the ability of MASW to detect a change in shear wave velocity as damage in concrete increases. The tests for establishing a recommended procedure for performing MASW on pavements was conducted at five sites at the University of Arkansas Engineering Research Center in Fayetteville, Arkansas. The five sites consisted of three materials: asphalt, concrete, and soil (two sites were on asphalt, two were on concrete, and one was on soil). The methods evaluated at these sites include the source type, distance from the source to the first receiver in the array (i.e., source offset), the spacing between receivers in the array, and the minimum number of receivers in the array. It was determined that for the data collected on asphalt, the optimum procedure included a 230g metal-tipped hammer, 2.5 cm receiver spacing, a minimum of 24 receivers, and source offsets of 12.5 cm, 25 cm, and 50 cm. For concrete, the optimum procedure included a 230g metal-tipped hammer, 5 cm receiver spacing, a minimum of 18 receivers, and source offsets of 12.5 cm, 25 cm, 50 cm, and 75 cm. For soil, the optimum procedure included a 230g metal-tipped hammer, 5 cm receiver spacing, a minimum of 12 receivers, and source offsets of 12.5 cm, 25 cm, and 50 cm. Additionally, it was determined from a limited data set of six tests, that MASW has the ability to detect a decrease in shear wave velocity as damage increases up to a strain level of at least 0.09%. However, MASW testing done on concrete with expansions of 0.09% and 0.29% showed only a 2% difference in shear wave velocity between the two large strain sections. Given the data collected it cannot be determined if MASW can be used to differentiate between concrete sections with strains larger than 0.09% (i.e., sections with heavy damage).