A controlled water production was performed at a water source of Ulaanbaatar city, Mongolia to evaluate the effectiveness of ground penetrating radar for detecting and monitoring dynamic groundwater movements in the subsurface. The groundwater level in Ulaanbaatar city area is between 2m-10m. This relatively shallow depth makes it a suitable target for detection by GPR. Field experiments in Ulaanbaatar were carried out in 2001 with 100 MHz antennae. We measured the groundwater level around a pumping well, then we monitored the change of the level after the pump was stopped. The groundwater level was about 5m. We could detect the groundwater change about 50cm, when the water level in the production well changed by 65cm. If we acquire the data by locating the antenna positions very accurately, we can obtain radar profiles with very high coherency, and we could see the groundwater migration clearly. The CMP was also used in the same site in order to determine the reflection from the groundwater surface. It was found that CMP and velocity analysis give a good information about the depth variation of the groundwater saturation in soil.
{"title":"Groundwater monitoring by GPR in Mongolia","authors":"Q. Lu, Motoyuki Sato","doi":"10.1117/12.462254","DOIUrl":"https://doi.org/10.1117/12.462254","url":null,"abstract":"A controlled water production was performed at a water source of Ulaanbaatar city, Mongolia to evaluate the effectiveness of ground penetrating radar for detecting and monitoring dynamic groundwater movements in the subsurface. The groundwater level in Ulaanbaatar city area is between 2m-10m. This relatively shallow depth makes it a suitable target for detection by GPR. Field experiments in Ulaanbaatar were carried out in 2001 with 100 MHz antennae. We measured the groundwater level around a pumping well, then we monitored the change of the level after the pump was stopped. The groundwater level was about 5m. We could detect the groundwater change about 50cm, when the water level in the production well changed by 65cm. If we acquire the data by locating the antenna positions very accurately, we can obtain radar profiles with very high coherency, and we could see the groundwater migration clearly. The CMP was also used in the same site in order to determine the reflection from the groundwater surface. It was found that CMP and velocity analysis give a good information about the depth variation of the groundwater saturation in soil.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"90 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124740400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Concrete inspection is a well-known use of GPR. The advent of modem GPR instruments combined with vastly increasing computing power and rapidly improving software permits more effective use of GPR. The impediment to wider use is now the ease-of-use of GPR technology for the average commercial user. The requirements for concrete inspection are many and varied. The most common is to clear areas prior to cutting and coring for the installation of utilities or renovations. The requirement is a quick means of knowing how to avoid critical elements such as posttension cables or embedded utilities. Structural applications address the integrity of the concrete itself such as the presence of voids/air pockets, chemical alteration, or cracking. Owing to the less well defined and site specific character of such features, GPR applicability is unpredictable and interpretation of results still depends on gaining experience with the specific site conditions. Intrusive investigation must augment GPR findings to draw definitive conclusions. The embedded object class of problems is readily tractable with GPR. In the last year we focused on development of a system which enables non-GPR specialists to image concrete. The system required integration of a GPR sensor with a positioning procedure and on site data processing in a single package. The output is depth slice maps that allow the operator to immediately select cutting and coring locations. Systematic ergonomic procedures to make operation easy for average concrete users represented a major challenge. In this paper we discuss the design considerations and present the final system embodiment. We use a number of data examples from real environments to illustrate the development.
{"title":"Application of GPR to map concrete to delineate embedded structural elements and defects","authors":"A. P. Annan, S. Cosway, T. DeSouza","doi":"10.1117/12.462215","DOIUrl":"https://doi.org/10.1117/12.462215","url":null,"abstract":"Concrete inspection is a well-known use of GPR. The advent of modem GPR instruments combined with vastly increasing computing power and rapidly improving software permits more effective use of GPR. The impediment to wider use is now the ease-of-use of GPR technology for the average commercial user. The requirements for concrete inspection are many and varied. The most common is to clear areas prior to cutting and coring for the installation of utilities or renovations. The requirement is a quick means of knowing how to avoid critical elements such as posttension cables or embedded utilities. Structural applications address the integrity of the concrete itself such as the presence of voids/air pockets, chemical alteration, or cracking. Owing to the less well defined and site specific character of such features, GPR applicability is unpredictable and interpretation of results still depends on gaining experience with the specific site conditions. Intrusive investigation must augment GPR findings to draw definitive conclusions. The embedded object class of problems is readily tractable with GPR. In the last year we focused on development of a system which enables non-GPR specialists to image concrete. The system required integration of a GPR sensor with a positioning procedure and on site data processing in a single package. The output is depth slice maps that allow the operator to immediately select cutting and coring locations. Systematic ergonomic procedures to make operation easy for average concrete users represented a major challenge. In this paper we discuss the design considerations and present the final system embodiment. We use a number of data examples from real environments to illustrate the development.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"195 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122023337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Pieraccini, G. Luzi, D. Mecatti, L. Noferini, C. Atzeni
In this paper a high-frequency large-bandwidth synthetic - aperture penetrating radar for inspecting masonry structures is described. A Continuous Wave Step Frequency (CW-SF) radar operating at 10 GHz centre frequency with 4 GHz bandwidth has been designed and built. The system is operated in a non-contact manner by mechanically moving the transmitting and receiving antennas in order to synthesize a N-dimensional aperture up to 3 m in length and 1 m in height. In spite of the fact that penetration depth decreases dramatically with increasing frequency, a penetration depth up to several tens of centimetres in masonry, that can be satisfactory in a number of applications, was observed. The high central frequency, making available very large bandwidths, provides high resolution images of the investigated structures. Laboratory tests in order to assess the performances of the system are reported.
{"title":"High-frequency penetrating radar for masonry investigation","authors":"M. Pieraccini, G. Luzi, D. Mecatti, L. Noferini, C. Atzeni","doi":"10.1117/12.462317","DOIUrl":"https://doi.org/10.1117/12.462317","url":null,"abstract":"In this paper a high-frequency large-bandwidth synthetic - aperture penetrating radar for inspecting masonry structures is described. A Continuous Wave Step Frequency (CW-SF) radar operating at 10 GHz centre frequency with 4 GHz bandwidth has been designed and built. The system is operated in a non-contact manner by mechanically moving the transmitting and receiving antennas in order to synthesize a N-dimensional aperture up to 3 m in length and 1 m in height. In spite of the fact that penetration depth decreases dramatically with increasing frequency, a penetration depth up to several tens of centimetres in masonry, that can be satisfactory in a number of applications, was observed. The high central frequency, making available very large bandwidths, provides high resolution images of the investigated structures. Laboratory tests in order to assess the performances of the system are reported.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125546521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT The GPR data acquisition software is arguably one of the most important components of a Ground Penetrating Radar system. This software needs to ensure the capture of reliable and repeatable data by a diverse user community. Yet, too many commercial and academic systems provide a single- user highly configurable interface for all applications. This paper describes the development of a configurable data acquisition and display application for use with ground penetrating radar. It is proposed that the standard GUI-based application that offers access to all controls and settings is distracting to many GPR end-users. It is therefore suggested that an application should present only the necessary controls to the end-user, and all other options should be inaccessible. This paper describes the development of such an application from a user requirements analysis to the design and implementation of an object-oriented, Java-based solution.
{"title":"Dynamically configurable GPR data acquisition and display application","authors":"A. Wallis, A. Langman, M. Inggs","doi":"10.1117/12.462295","DOIUrl":"https://doi.org/10.1117/12.462295","url":null,"abstract":"ABSTRACT The GPR data acquisition software is arguably one of the most important components of a Ground Penetrating Radar system. This software needs to ensure the capture of reliable and repeatable data by a diverse user community. Yet, too many commercial and academic systems provide a single- user highly configurable interface for all applications. This paper describes the development of a configurable data acquisition and display application for use with ground penetrating radar. It is proposed that the standard GUI-based application that offers access to all controls and settings is distracting to many GPR end-users. It is therefore suggested that an application should present only the necessary controls to the end-user, and all other options should be inaccessible. This paper describes the development of such an application from a user requirements analysis to the design and implementation of an object-oriented, Java-based solution.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130240348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
GPR surveys were conducted at two sites within the hillside town of Rennes-le-Château, France. The town is linked with many traditions and mysteries associated with the Templar movement and its treasure, including according to some documents, the possible location of the Holy Grail. Two locations were chosen for the initial project: the Tour Magdala and the Church of St. Mary Magdalen. The survey at the Tour Magdala was carried out to image any features that may be located beneath the tower floor or around its outer base. Results indicate the tower is built on the local bedrock with possible surface and subsurface disruptions in the local stratigraphy, while 3D cubes show a hyperbolic feature, which may indicate the possibility of a buried feature. The survey at the Church was carried out to image any features that may be located beneath the church floor. 2D and 3D images show a subsurface anomaly (hyperbolic feature) that extends along several parallel lines that may possibly indicate a burial crypt.
{"title":"Archaeological GPR investigation at Rennes-le-Chateau, France","authors":"H. Jol, R. J. DeChaine, R. Eisenman","doi":"10.1117/12.462201","DOIUrl":"https://doi.org/10.1117/12.462201","url":null,"abstract":"GPR surveys were conducted at two sites within the hillside town of Rennes-le-Château, France. The town is linked with many traditions and mysteries associated with the Templar movement and its treasure, including according to some documents, the possible location of the Holy Grail. Two locations were chosen for the initial project: the Tour Magdala and the Church of St. Mary Magdalen. The survey at the Tour Magdala was carried out to image any features that may be located beneath the tower floor or around its outer base. Results indicate the tower is built on the local bedrock with possible surface and subsurface disruptions in the local stratigraphy, while 3D cubes show a hyperbolic feature, which may indicate the possibility of a buried feature. The survey at the Church was carried out to image any features that may be located beneath the church floor. 2D and 3D images show a subsurface anomaly (hyperbolic feature) that extends along several parallel lines that may possibly indicate a burial crypt.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"243 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134145657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A three-dimensional (3-D) georadar survey has been conducted across a 41.2 x 34.5m area with moderate topographic relief (dips: 4 - 16°) near Randa in southwestern Switzerland. For this survey, we employed a semiautomated acquisition system that combined a standard georadar unit with a self-tracking theodolite. This system recorded georadar data and coordinates simultaneously. Subsequently, an accurate topographic model of the acquisition surface was determined from the measured coordinates. With the aid of this topographic model, a provisional static correction for each georadar trace was determined. Application of the static corrections removed the most significant distortions of the major reflections and diffractions, which likely originated from the soil-rock interface and/or major fractures.
在瑞士西南部Randa附近的一个41.2 x 34.5m的区域进行了三维(3-D)地质雷达调查，该区域地形起伏适中(倾角:4 - 16°)。在这次调查中，我们采用了一种半自动采集系统，该系统将标准地质雷达单元与自跟踪经纬仪相结合。该系统同时记录地质雷达数据和坐标。随后，根据测量坐标确定采集面精确的地形模型。利用该地形模型，确定了每条地质雷达道的临时静校正量。静校正的应用消除了主要反射和衍射的最显著畸变，这些畸变可能源于土-岩界面和/或主要裂缝。
{"title":"3D georadar surveying in areas of moderate topographic relief","authors":"B. Heincke, T. Spillmann, H. Horstmeyer, A. Green","doi":"10.1117/12.462261","DOIUrl":"https://doi.org/10.1117/12.462261","url":null,"abstract":"A three-dimensional (3-D) georadar survey has been conducted across a 41.2 x 34.5m area with moderate topographic relief (dips: 4 - 16°) near Randa in southwestern Switzerland. For this survey, we employed a semiautomated acquisition system that combined a standard georadar unit with a self-tracking theodolite. This system recorded georadar data and coordinates simultaneously. Subsequently, an accurate topographic model of the acquisition surface was determined from the measured coordinates. With the aid of this topographic model, a provisional static correction for each georadar trace was determined. Application of the static corrections removed the most significant distortions of the major reflections and diffractions, which likely originated from the soil-rock interface and/or major fractures.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134240656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Continuing improvements in computer technology have made 3-D imaging a standard GPR interpretation technique. The most common data collection methodology for 3-D imaging involves collection of data along parallel profile lines. The data are then often migrated and concatenated into a 3-D file. A 3-D image generated from the file is manipulated to detect linear and finite-size targets. The detection of linear and finite-size targets can be enhanced by creating images generated from data collected along orthogonal profile lines. The fact that the minimum angle formed between the long axis of a linear target and one of the orthogonal profile lines is 45 degrees enhances the detection of a linear target because in at least one profile line direction the reflection from the linear target will form the familiar hyperbola and a series of hyperbolas concatenated from parallel profile lines are readily observed in the 3-D image. Perhaps the most beneficial aspect of using bi-directional data is the ability to perform spatial filtering operators to improve detection of linear targets. Background removal filters applied to parallel profile line data will generally erase reflections from pipes or rebar that trend parallel to the direction of the profile lines. Comparisons of the data visualization capabilities between one-direction and orthogonal profile line data collected on reinforced concrete and on a buried pipe test site clearly show the advantages of imaging using orthogonal profile line data on both small and large scales.
{"title":"Enhanced target imaging in 3D using GPR data from orthogonal profile lines","authors":"R. Roberts, D. Cist","doi":"10.1117/12.462227","DOIUrl":"https://doi.org/10.1117/12.462227","url":null,"abstract":"Continuing improvements in computer technology have made 3-D imaging a standard GPR interpretation technique. The most common data collection methodology for 3-D imaging involves collection of data along parallel profile lines. The data are then often migrated and concatenated into a 3-D file. A 3-D image generated from the file is manipulated to detect linear and finite-size targets. The detection of linear and finite-size targets can be enhanced by creating images generated from data collected along orthogonal profile lines. The fact that the minimum angle formed between the long axis of a linear target and one of the orthogonal profile lines is 45 degrees enhances the detection of a linear target because in at least one profile line direction the reflection from the linear target will form the familiar hyperbola and a series of hyperbolas concatenated from parallel profile lines are readily observed in the 3-D image. Perhaps the most beneficial aspect of using bi-directional data is the ability to perform spatial filtering operators to improve detection of linear targets. Background removal filters applied to parallel profile line data will generally erase reflections from pipes or rebar that trend parallel to the direction of the profile lines. Comparisons of the data visualization capabilities between one-direction and orthogonal profile line data collected on reinforced concrete and on a buried pipe test site clearly show the advantages of imaging using orthogonal profile line data on both small and large scales.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121182891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Optimal frequency bands for radar detection of buried anti-tank (AT) and anti-personal (AP) mines are substantiated. Mines geometry, permittivity of explosives and soils are taken into account. In that case we can obtain maximum number of parameters for identification of mines against a background of noises and false signals. Analysis of used antennas of ground penetrating radar (GPR) is completed. For improvement of mine detection probability we propose to use scanning antennas and focused scanning antennas.
{"title":"Novel method of plastic landmine radar detection","authors":"N. Chubinsky, A. Krampuls","doi":"10.1117/12.462312","DOIUrl":"https://doi.org/10.1117/12.462312","url":null,"abstract":"Optimal frequency bands for radar detection of buried anti-tank (AT) and anti-personal (AP) mines are substantiated. Mines geometry, permittivity of explosives and soils are taken into account. In that case we can obtain maximum number of parameters for identification of mines against a background of noises and false signals. Analysis of used antennas of ground penetrating radar (GPR) is completed. For improvement of mine detection probability we propose to use scanning antennas and focused scanning antennas.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121224510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To understand better how a borehole antenna radiates radar waves into a formation, this phenomenon is simulated numerically using the finite-difference, time-domain method. The simulations are of two different antenna models that include features like a driving point fed by a coaxial cable, resistive loading of the antenna, and a water-filled borehole. For each model, traces are calculated in the far-field region, and then, from these traces, radiation patterns are calculated. The radiation patterns show that the amplitude of the radar wave is strongly affected by its frequency, its propagation direction, and the resistive loading of the antenna.
{"title":"Radiation pattern of a borehole radar antenna","authors":"K. Ellefsen, D. Wright","doi":"10.1117/12.462190","DOIUrl":"https://doi.org/10.1117/12.462190","url":null,"abstract":"To understand better how a borehole antenna radiates radar waves into a formation, this phenomenon is simulated numerically using the finite-difference, time-domain method. The simulations are of two different antenna models that include features like a driving point fed by a coaxial cable, resistive loading of the antenna, and a water-filled borehole. For each model, traces are calculated in the far-field region, and then, from these traces, radiation patterns are calculated. The radiation patterns show that the amplitude of the radar wave is strongly affected by its frequency, its propagation direction, and the resistive loading of the antenna.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129522002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dolores Ibanez Garduno, R. Álvarez, Victor H. Garduno Monroy, I. Israde-Alcántara, E. Arreygue-Rocha
Urban areas built on old lacustrine basins in central Mexico show subsidence related to creep-fault processes. These processes are highly dynamic and enhanced by aquifer water extraction and El Nino events. The affected cities are Morelia, Salamanca, Silao, Celaya, Aguascalientes, and Queretaro, with a global population of around 2.5 million, and considerable industrial assets. The first three cities show NE-SW creep-fault trends, while in the remaining the trend is N-S. The subsidence rate varies: 2-3 cm/year at Salamanca, 4-6 cm/year at Morelia and Queretaro, and 6-8 cm/year at Celaya. In order to preliminarily evaluate the effects of the creep-faults, we performed a series of non-destructive ground penetrating radar surveys in the city of Morelia, that complement concurrent geological studies of the area. We report herein results in three locations where the surface expression of the faults is well defined, including substantial damage to homes and buildings. One of the objectives was to determine the length of the disturbance, perpendicular to the faults' trends. Using 50 Mhz antennas we reached an exploration depth of around 10 m in sandstone-bearing lacustrine deposits and lava flows. In most cases the faults show low-angle dips that vary with depth in the main fault. Additional, synthetic and antithetic faults are developed in the disturbed area of the main fault, which we define as the influence zone of the main disturbance. We find that this zone varies from 15 to 50 m on both sides of the fault, although it tends to be larger on the down thrown block. Faulting appears to be controlled by geological formations within the first 10-15 m in depth.
{"title":"GPR assessment of creep-fault-induced damage in urban areas","authors":"Dolores Ibanez Garduno, R. Álvarez, Victor H. Garduno Monroy, I. Israde-Alcántara, E. Arreygue-Rocha","doi":"10.1117/12.462248","DOIUrl":"https://doi.org/10.1117/12.462248","url":null,"abstract":"Urban areas built on old lacustrine basins in central Mexico show subsidence related to creep-fault processes. These processes are highly dynamic and enhanced by aquifer water extraction and El Nino events. The affected cities are Morelia, Salamanca, Silao, Celaya, Aguascalientes, and Queretaro, with a global population of around 2.5 million, and considerable industrial assets. The first three cities show NE-SW creep-fault trends, while in the remaining the trend is N-S. The subsidence rate varies: 2-3 cm/year at Salamanca, 4-6 cm/year at Morelia and Queretaro, and 6-8 cm/year at Celaya. In order to preliminarily evaluate the effects of the creep-faults, we performed a series of non-destructive ground penetrating radar surveys in the city of Morelia, that complement concurrent geological studies of the area. We report herein results in three locations where the surface expression of the faults is well defined, including substantial damage to homes and buildings. One of the objectives was to determine the length of the disturbance, perpendicular to the faults' trends. Using 50 Mhz antennas we reached an exploration depth of around 10 m in sandstone-bearing lacustrine deposits and lava flows. In most cases the faults show low-angle dips that vary with depth in the main fault. Additional, synthetic and antithetic faults are developed in the disturbed area of the main fault, which we define as the influence zone of the main disturbance. We find that this zone varies from 15 to 50 m on both sides of the fault, although it tends to be larger on the down thrown block. Faulting appears to be controlled by geological formations within the first 10-15 m in depth.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129638784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：