Application Of Geophysical Methods Research Articles

Extensive surface geophysical prospecting for seismic microzonation

This paper presents an overview of the geophysical activities for the seismic microzonation of 138 municipalities belonging to four Italian regions (Abruzzo, Lazio, Marche and Umbria) that were severely damaged by the seismic sequence of Central Italy (August 2016–January 2017). This study is the result of a collaborative effort between research Institutions and professional geologists with the support of local Administrations and the Italian Civil Protection Department and sets an unprecedented large-scale example of geophysical investigations supporting detailed seismic microzonation studies. This manuscript presents the methodological approach adopted for the geophysical activities, including the technical protocols and procedures, the best practices, the final products and the results supporting a detailed microzonation study of III level. The first step of the study was the collection and critical review of all available geophysical and geological information for planning the new geophysical surveys (specifically their type and location), in order to assess the subsoil geometry and the seismic characterization of the areas under investigation. Integration with the newly acquired geophysical data allowed the identification of zones with homogeneous local seismic hazard as well as the reference seismo-stratigraphy for each area, defining for each geological unit the ranges of the relevant properties in seismic amplification studies: layering and thicknesses, density, P-wave and S-wave seismic velocity. We also present a few representative case studies illustrating the geophysical investigation for different geomorphological situations. These examples, together with the findings of the entire project, are discussed to point out the strength points and the criticalities, as well as the necessary requirements in the application of geophysical methods to detailed microzonation studies.

ИССЛЕДОВАНИЕ АВАРИЙ НА ГИДРОТЕХНИЧЕСКИХ СООРУЖЕНИЯХ И МЕТОДЫ КОНТРОЛЯ ИХ БЕЗОПАСНОСТИ

Актуальность исследования.На сегодняшний день проблемы безопасности объектов водного хозяйства, в особенности плотин, дамб и других гидротехнических сооружений, остро стоят в обществе. Это связано, прежде всего, с большими экономическими, экологическими и социальными потерями, к которым приводят разрушения подобных объектов. В этой связи очевидна необходимость максимального снижения вероятности таких событий. Этот вывод в полной мере относится и к гидротехническим сооружениямв Республике Казахстан, большинство которых были построены в 60–80 гг. прошлого столетия и были случаи возникновения аварийных ситуаций. Наиболее значимые из них – прорыв земляных плотин в Кызылагаше в 2010 г. и в Кокпектыв 2014 г. В последнее время интенсивное развитие стало получать применение новых инновационных методов контроля за гидротехническими сооружениями, в том числе геофизических методов. Интерпретация результатов геофизических измерений может более детально охарактеризовать строение и физико-механические свойства пород, слагающих тело земляных плотин. В этом заключается актуальность данной работы, которую можно считать базой для проведения дальнейших исследований и применения геофизических методов на плотинах земляного типа в Республике Казахстан. Цель: выбор оптимального комплекса геофизических методов для последующего опробования их на гидротехнических сооружениях земляного типа. Объектом исследованияявляются причины аварий на гидротехнических сооруженияхи методы контроля за их состоянием. Методика: проведение анализа причин разрушений гидротехнических сооружений, анализ информативности геофизических методов при изучении строения плотин с обоснованием оптимального комплекса для диагностики и прогнозирования технического состояния земляных плотин. В результате исследованиявыбран оптимальный комплекс геофизических методов: электрическая и сейсмическая разведка, георадарное зондирование. Данный комплекс будет в дальнейшем опробован на плотинахземляного типа.

Application of Geophysical Methods in Stability Assessment of Slopes within Historical Natural-Technical Systems

The article is concerned with the use of geophysical methods in engineering geological surveys on landslide-prone slopes. The article discusses research methods that allow to obtain the necessary parameters for computer simulation and based on this performing slope stability assessment. As examples the slopes within the historical natural-technical systems (HNTS) are considered as the sustainability issues are of particular importance for them.

ГЕОФІЗИЧНІ ДОСЛІДЖЕННЯ ЗСУВНИХ ТЕРИТОРІЙ ПРАВОГО БЕРЕГА РІЧКИ ДНІПРО (ЛІСОСТЕПОВА ЗОНА)

The paper discusses the details of the application of geophysical research methods in the study of the landslide areas of the right bank of the Dnieper River within the forest-steppe zone of Ukraine. Geological and geophysical models of landslides are given. The specific tasks that are posed in studies of landslides were highlighted. There are three stages in studies of landslides which were defined: reconnaissance-methodological, detailed and monitoring. Also, sets of geophysical methods for these stages were designated. It is emphasized that the rational set of geophysical methods in the study of landslide processes is determined for each individual natural environment, taking into account: the possibility of performing field studies by a specific geophysical method on the area; the presence of differentiation of rocks by physical properties, that are used by the specific geophysical method; economic efficiency of application of the geophysical method. As an example, we described some of the results of geophysical studies, which were carried outon exemplary landslidesites onthe right bank of the Dnieper River within the forest-steppe zone of Ukraine near the Trypillia thermal power plant.

Geophysical Investigation of the Triassic Salt Material Hazard: El Fahs Case Example (Northern Tunisia)

The Tunisian territory (area of diapirs) is exposed to the risks of ground movements linked to water, some of which are related to the phenomenon of dissolution of gypsum, allowing the appearance of underground cavities which present natural risks and set people in danger. The analysis of the hazard was determined by the field study coupled with the application of geophysical methods to locate and map the cavities and identify their dimensions and their positions in the subsoil. In the region of El Fahs (40 km NW of Tunis): we used a non-destructive method, georadar (GPR) with a 200 MHz antenna band-width, and an electric method, by using the electric tomography of which we have applicated the sequence of dipole-dipole measurement. The results ob-tained were examined and interpreted according to 2D profiles. The geophysi-cal methods of GPR and electrical tomography aim to detect many calvities in different depths. However, the geological radar was able to identify several cavities and the zones of dissolution whose investigation depth did not exceed the first 3 meters. On the contrary, the electric tomography method allowing the presence of several deeper underground cavities with larger dimensions ex-tended to 64 meters. To conclude, the geological and hydrogeological contexts of the terrain studied and on the state of the soil and subsoil allow us to better understanding the mechanisms of the establishment of the dissolution phe-nomenon and the appearance of cavities in the basement. The analysis of the predisposing factors present in the study area shows that the geodynamic con-text of the Triassic ascent takes place according to a precise thermodynamic process that favors the phenomenon of dissolution of the gypsum.

Study of Generation and Underground Flow of Acid Mine Drainage in Waste Rock Pile in an Uranium Mine Using Electrical Resistivity Tomography

Mineral exploration is often associated with the generation of environmental liabilities, whose potential damages might imperil local water quality. An example of these environmental impacts is the acid mine drainage—AMD, caused by sulfides oxidation and production of acid and saline effluents. The analysis of critical areas with generation and spread of contamination plumes becomes more feasible due to the possibility to obtain geophysical models of water systems, especially to identify regions with accumulation of reactive minerals and preferential water flows. The rock-waste pile named BF-04 fits in this context of contamination, and it was studied based on the Electrical Resistivity Tomography technique, inversion models and isosurface models, providing conditions to recognize sulfide zones (> 10.1 mV/V), whereas chaotic high salt content underground flows, along several depths, were identified by low resistivity zones (< 75.8 Ω m). The complex behavior of groundwater flow in this kind of artificial granular aquifer is caused by its granulometric and lithologic heterogeneities, and compacted material. In addition, the results reveled a substantial water infiltration from Consulta creek, however the most critic zones for AMD generation are located at shallow levels where the waste rock material is more exposed to atmospheric O2 and meteoric water infiltration. The bedrock was not associated with significant low resistivity anomalies, which means that its contribution to AMD generation was considered relatively less important. The results will contribute to the environmental remediation management and also to demonstrate the potential applicability of geophysical methods in mining wastes.

EXPERIMENTATION AND INDIRECT METHODS APPLIED TO INVESTIGATE THE CONTAMINATED AREAS

O presente artigo tem por objetivo principal apresentar as diferentes metodologias geofísicas, suas definições, características e potencialidades, exemplificando quais seriam os mais adequados métodos para cada tipo de situação envolvida na investigação da contaminação subterrânea. No desenvolvimento do texto, é abordada a temática de áreas contaminadas e suas fontes de contaminação, os termos conceituais da metodologia geofísica, o histórico no Brasil dos estudos ambientais para investigação da qualidade do solo e água subterrânea, o enquadramento da Geofísica Ambiental no Gerenciamento de Áreas Contaminadas e apontamentos quanto às normas de referência nacionais e internacionais sobre a aplicação dos métodos geofísicos em estudos de contaminação subterrânea. Além disso, são apresentados os aspectos teóricos em que se fundamentam os métodos geofísicos aplicados aos estudos ambientais, bem como exemplos de aplicação e que se constituem em casos onde a metodologia foi empregada com sucesso e contribuiu de forma relevante para o diagnóstico ambiental dos locais investigados. A relevância deste tipo de divulgação, além do aspecto de apresentação dos métodos geofísicos e de sua importância para diferentes profissionais da área ambiental, também traduz a necessidade de atualização dos textos técnicos sobre o tema, haja vista que o Manual de Áreas Contaminadas da CETESB, que é a referência principal que congrega os métodos aqui descritos, já completa quase duas décadas de sua publicação e, atualmente, não está disponível para consultas. Ao final deste artigo técnico, são apresentadas tabelas orientativas quanto à aplicação dos métodos geofísicos para a detecção de contaminação por diversos tipos de contaminantes, e referente à influência do material geológico local e relativa às características, potencialidades e limitações dos métodos geofísicos aqui abordados.

Application of Cross-Hole Tomography for Assessment of Soil Stabilization by Grout Injection

Currently, the spread of megalopolises poses an ever-increasing necessity for underground space development for the purpose of the arrangement of transport communications, underground parking areas, trade areas, etc. The implementation of such projects entails a significant increase in the risk of accidents and damage to existing buildings within construction activity influence areas. The reduction of the risk of accidents during the construction of underground facilities within urban areas may only become possible with the identification of adverse factors negatively influencing existing buildings or a facility under erection and elaboration (to reduce such negative influence). The application of geophysical methods in complex assessments of the actual state of an encompassing mass significantly increases efficiency and the credibility of geotechnical monitoring. The application of seismic tomography significantly increases the resolution capability of surveys. Existing techniques, e.g., seismic tomography, allow for any depths to be investigated at a high resolution, even given constricted urban conditions. This article covers the practical applications of seismic tomography in qualitative assessments of actions and an efficiency evaluation of the injective stabilization of soil.

DELINEATION OF SUBSURFACE STRUCTURES OF SEMANGGOL FORMATION, NORTH PERAK USING MAGNETIC DATA

The Semanggol Formation has been studied widely and published by many, but only focus on areas of northern and southeast Kedah. Limited data have been studied and published on Perak area, especially Gunung Semanggol. The research is aimed to augment the presently limited knowledge on the hill, particularly the subsurface structure. In addition, new lithology such as a breccia formation with tens of meters width of what appears to be a breccia granitic matrix was identified in an abandoned quarry. Therefore, a study on the application of geophysical methods covering the Semanggol Formation located at Semanggol area has been carried out. The main aim of this study was to conduct a magnetic survey to study the subsurface and possibility of granitic bodies in Gunung Semanggol. The total magnetic field data were obtained by using a proton free-precision magnetometer, recording the total ground magnetic field along the transverse. There was a total of 184 magnetic stations established during the survey with a 500 m to 1 km spacing. Data reduction was processed using Oasis Montaj software to produce Total Magnetic Intensity (TMI), Reduction to Pole (RTE), Regional Anomaly and Residual Anomaly maps for qualitative interpretation. The interpreted field data gave the results of total component measurements of magnetic anomaly varying between minimum negative value around 180 nanoTesla (nT) and maximum around 510 nanoTesla (nT) as shown in TMI map. Besides, the regional magnetic map shows a gradual decrement of magnetic intensity towards east and southeast. And residual magnetic map reveals that the dominant orientation for magnetic lineaments in the NE-SW direction. However, geochemical tests have to be conducted to study the possibility of granitic bodies.

Geophysical response to simulated methane migration in groundwater based on a controlled injection experiment in a sandy unconfined aquifer

Geophysical methods have the capacity to detect and characterize gas-phase dynamics in groundwater. Suitable methods can be deployed at surface or within boreholes depending on the required depth of investigation, spatial/temporal resolution, and geologic conditions. While the application of geophysical methods to monitor immiscible phase contaminants in the subsurface has been extensively documented, the effects of hydraulic properties and flow system conditions on the nature of the geophysical responses used to elucidate multi-phase fluid flow remains underdeveloped. A series of numerical 2-dimensional multi-phase flow and geophysical model simulations based on a controlled methane release experiment in the Borden unconfined sand aquifer was carried out to assess the influence of porous media hydraulic properties and flow system conditions on geophysical signatures associated with transient gas-phase saturation and gas migration behaviour. Specifically, the utility of electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) to monitor gas-phase plume dynamics in shallow groundwater flow systems is examined. ERT and GPR responses to gas-phase distribution and migration during a 72-day methane gas injection and subsequent recovery period was calculated using a numerical multi-phase flow model (CFbio) simulating four distinct parameterizations of the sandy aquifer system. Geophysical models showed that ERT was effective at imaging the central position of the plume but was less effective at detecting thinner lateral migration pathways extending beyond the primary high gas saturation bulb. Conversely, GPR was able to detect thin gas pools emanating from the primary gas bulb and small-scale vertical preferential pathways arising from capillary boundaries with contrasting saturations; however, gradational boundaries proved to be more difficult to resolve using GPR. This study demonstrates that ERT and GPR can be very useful tools in combination for longer-term monitoring of stray gas leakage from decommissioned hydrocarbon wells in shallow granular media freshwater aquifers, especially given the likelihood of strong lateral migration.

Introduction to this special section: Near-surface geophysics

The near surface of the earth, a.k.a. the critical zone (National Research Council, 2001), is defined as the outer 50–100 m of the planet, which contains biota, bedrock, soil, water, and gasses. As humans, we rely on this layer for many functions including storage of water resources, housing of our infrastructure, storage of our wastes, and cultivation of our food sources. Several natural ecosystems are also dependent on this layer of our planet, which in turn provide us with ecosystem services. The historic and lasting importance of this layer to our environment emphasizes the value in understanding major environmental fluxes, impact of human activities, and the interface between the natural world and our infrastructure. Application of geophysical methods in this field has increased steadily over the past 15 years and continues to grow, especially as the human impact on the globe continues to increase.

Recognition of Lower Cretaceous geothermal potential of Central Poland with the application of geophysical methods

In Poland, geothermal energy and waters are utilized in several geothermal plants as well as in balneological and recreation centers. The research projects run in last years aimed to recognize the geothermal potential in various regions of Poland. These projects were especially focused on selection of sites prospective for development of geothermal resources. For this purpose, various integrated exploration methods were applied to reduce the geological risk, which affects any design of geothermal installation. Among the convenient exploration tools are geophysical methods widely applied to the recognition of geological structure of the Earth and to petroleum exploration. Taking into account the Malanów area located in the Mogilno-Łódź Trough (central part of the Polish Lowlands), the authors present the opportunities provided by the usage of archival geophysical data for characterization of geothermal aquifer. The results demonstrate that geophysical methods can effectively support the selection of areas favorable for future geothermal investments. Simultaneously, such methods can be useful in determination of hydrogeothermal parameters of particular aquifer. In the study area, local depressions of the top surface of geothermal aquifer are known, which can be identified with the seismic data. Moreover, seismic inversion can be applied to porosity estimations of Lower Cretaceous aquifer. The most favorable reservoir properties occur in the NE part of the study area where the top surface of Lower Cretaceous formation is located at < 1500 m depth and in its marginal parts where this surface drops down to even 1900 m depth. Seismic data also indicate that the Lower Cretaceous aquifer remains tectonically undisturbed.

Seismic Methods in Geothermal Water Resource Exploration: Case Study from Łódź Trough, Central Part of Poland

The geothermal waters constitute a specific type of water resources, very important from the point of view of their thermal energy potential. This potential, when utilized, supplies an ecological and renewable energy, which, after effective development, brings many environmental, social, and industrial benefits. The key element of any geothermal investment is the proper location of geothermal installation, which would guarantee the relevant hydrogeothermal parameters of the water intake. Hence, many studies and analyses are carried out in order to characterize the reservoir parameters, including the integrated geophysical methods. For decades, the geophysical surveys have been the trusty recognition methods of geological structure and petrophysical parameters of rock formations. Thus, they are widely applied by petroleum industry in exploration of conventional and unconventional (shale gas/oil, tight gas) hydrocarbon deposits. Advances in geophysical methods extended their applicability to many other scientific and industrial branches as, e.g., the seismic survey used in studies of geothermal aquifers. The following paper presents the opportunities provided by seismic methods applied to studies of geothermal resources in the central Poland where the geothermal waters are reservoired in both the Lower Cretaceous and the Lower Jurassic sedimentary successions. The presented results are obtained from a network of seismic profiles. An important advantage of the seismic survey is that they may support the selection of an optimal location of geothermal investment and determination of the geometry of geothermal aquifer. Furthermore, the application of geophysical methods can significantly contribute to the reduction of estimation error of groundwater reservoir temperature.

Application of Geophysical Methods on Geothermal Resource Exploration: A Case of Shores of Lake Malawi

Application of Geophysical Methods on Geothermal Resource Exploration: A Case of Shores of Lake Malawi

Verification of applied geophysical procedures to standardize protocols for geothermal exploration in Central America

Although a large amount of geothermal exploration data exists in Central America since the 1960s, it has not yet lead to an even development of capacities in the region. Exploration methods and applied interpretations techniques did not evolve in many cases, due to a lack of knowledge exchange on a geoscientific level.To improve this situation, a verification of applied geophysical procedures will be developed by the InstitutoCostarricense de Electricidad (ICE, Costa Rica). Current international standards and updated approaches, including environmental aspects, will be taken into consideration to create guidelines on the application of geophysical methods for geothermal exploration in Central America. This is an important step to equalize the capacities of regional governmental institutions in the field of geothermal exploration and to enhance the comparability of geophysical exploration results in the region. The project is supported by the Federal Institute for Geosciences and Natural Resources (BGR, Germany) in the framework of the German Cooperation with the Sistema de IntegraciónCentroamericano (SICA) for the Identification of Geothermal Resources in Central America. The activities are in the conceptualization phase and a field campaign in the AOI Las Pailas II Geothermal Project is planned for the third quarter of 2018.

A journey to Earth Science Projects at Physics Department, the State University of Surabaya: progress in recent years

Earth Science Projects are research topics conducted by some people working on subjects related to hazard mitigation study on the basis of all efforts in disaster risk reduction through maximizing awareness of science and minimizing all risks of earth-related disasters. These people have joined Center for Earth Science Studies at Physics Department since 2011 and performed computational work, focusing on tsunamis, earthquakes, and volcano eruptions for reliable early warning system development. Other work has in part examined applications of geophysical methods to localize hydrocarbon reservoirs using analysis of broadband-noise spectral amplitude and low-frequency spectrogram, and distinguish underground nuclear tests from natural earthquakes of seismic origin. The Projects may also be relevant to science and/or physics education students as final projects with earth-related disasters as the main themes using laboratory approaches. Several publications made by the group members and students in recent years are therefore discussed, emphasizing on seismic hazard assessment and analysis. Future direction of possible research collaboration between research groups in the department will also be discussed in terms of challenges and technical difficulties.

Application of geophysical methods for the subsurface treatment of the Piekary highway junction in shallow mining terrain

The study presents the application of geophysical methods in the subsurface treatment of the A-1 highway in the area of the Piekary junction in the terrain of historic zinc and lead ore mining, in the northern part of the Upper Silesian Coal Basin in Poland (USCB). The study area was under threat of discontinuous deformations, mainly sinkholes. This threat resulted from the shallow exploitation of zinc and lead ores, as well as contemporary exploitation of coal seams at greater depths. An original methodology of subsurface treatment has been developed as an adaptation to the geophysical measurement results. The methodology uses the gravimetric method at the initial and final control stages, as well as the seismic and borehole georadar methods during the detailed evaluation stage. The results of the study allowed different categories of sinkhole hazard to be determined in the area of the Piekary junction. The scope of the liquidation works was selected to match the hazard levels. Blasting of varying intensities and the borehole injection of the filling material were performed. The combination of substrate treatment methodologies and highway construction protection systems have proved to be effective.

Application of geophysical methods in a dam project: Life cycle perspective and Taiwan experience

There is a growing demand for using non-destructive geophysical techniques to internally image dam condition and facilitate the early detection of anomalous phenomena. Near surface geophysical techniques have advanced significantly in the last few decades, and can play a significant role in the siting, construction, and operational safety and sustainable management of dams. Application of engineering geophysics in site characterization during feasibility investigation phase is already part of the standard of practice. This paper introduces newer applications of engineering geophysics during construction phase, dam safety assessment, and sustainable management, including quality control of compacted soils, investigation of abnormal leakage in an earth dam, evaluation of an aged concrete dam, geophysical health monitoring for a newly-constructed dam, and monitoring of sediment transport for sediment management. The applications were presented with more emphases on the needs of dam engineering and adapting appropriate geophysical methods to make assessment more effective and consequential. The collage of these case studies is to broaden the view of how geophysical methods can be applied to a dam project throughout a dam's life cycle and strengthen the linkage between geophysical surveillance and engineering significance at all stages.

Application of geophysical methods for solving hydrogeoecological problems in the Southern Kryvbas territory

The geoecological impact of various man-made mining facilities in the Southern Kryvbas territory was studied using a complex of geophysical methods (gravity-magnetic prospecting; electrical exploration by the VES method and interpretation of aero-space photographs). The predetermining role of the tectonic factor in assessing the hydrogeoecological situation in the research area is shown. The prevalence of diagonal and sublatitudinal faults of high ranks (dividing the submeridional extension of metamorphic rocks of the Kryvyi Rih series into a system of small blocks) has been established by detailed geological-geophysical studies. Their vertical movements “unload” periodically arising stresses in the Earth’s crust. A high level of activation of dangerous geoecological (and primarily hydrogeoecological) processes is marked as a result of the interaction of natural geodynamic and technogenic processes. It is shown (based on the complex analysis of hydro-geological and geophysical information) that the highly mineralized mine and open-pit waters of the tailing dumps of the PJSC “Yugok” and the PJSC “Arcelor Mittal Kryviy Rih” and mine water storage pond in the Svistunova ravine of State enterprise “Kryvbasshakhtozakrytiei” have a joint effect on the hydro-geoecological situation of Southern Kryvbas territory. The flooding of the study area by results of the research is not universal; it takes into account modern features of the activation of fault tectonics.

2D electrical resistivity tommorgraphy for environmental, engineering and hydrogeological application in Igarra, Nigeria

The application of geophysical method in subsurface investigation at several locations in Igarra, Nigeria has revealed detailed information about the hydrogeological and geotechnical implication of the surveyed locations. Electrical resistivity survey using the wenner-schlumberger array configuration used to characterize a total of fifteen profiles in a sedimentary environment. The true resistivity structures were interpreted using Zondres2D program for 2D smoothness constrained inversion. The outcome of this 2D study includes delineation of aquiferous layers and their recharge zone, and the estimation of its depth in Onumu area, the geotechnical analysis of the soil structure in supporting road construction in Ogbe area, and the environmental prospects and problems in Isale and Ayetoro areas respectively. The essence of this study is to emphasis the usefulness of 2D resistivity mapping as a powerful geological mapping tool from which reliable sections of the subsurface can be created. Keywords: 2D resistivity mapping, geotechnical analysis, wenner-schlumberger array, hydrogeological implication