Geophysical Investigations Research Articles

High resolution multi-methodological geophysical investigations to enhance the knowledge of Tusculum archaeological site (Roma, Italy)

To better understand the location and help in the conservation of buried structures in the ancient site of Tusculum, in Central Italy, archaeological and multi-methodological geophysical studies were developed in the recent last years. These studies included geophysical surveys, which were combined with topographical survey and direct archaeological excavations. Tusculum is one of the largest Roman archaeological sites in the Alban Hills, located in the Latium region (Italy), about 25 km South-East of Rome. This settlement was inhabited since pre-Roman times, up to the middle ages. The objective of the Tusculum Project is to verify the town-planning of Tusculum and to obtain information about the location, shape, depth and size of the hypothesised buried buildings. With these aims, multi-methodological geophysical surveys have been carried out in the time range 2016–2019 to locate the archaeological remains in different portions of the studied area and to verify the orientation of the underground aqueduct system. GPR and gradiometric surveys were carried out to investigate the archaeological remains, while ERT surveys, were employed to find evidence of undiscovered parts of the underground aqueduct system. These results, along with geological studies and historic evidence, are being examined by archaeologist to understand the limits of the town and how water was supplied to such a large, populated settlement. The obtained results show very good correspondence between the buried architecture, the geophysical anomalies and the archaeological excavations. A number of unexpected buried buildings were discovered, which were excavated in 2017 and 2018, which showed remains of buried public thermal bath and a large church with surrounding funerary area built in the Middle Ages.

Combining Ground Penetrating Radar and Frequency Domain Electromagnetic Surveys to Characterize the Structure of the Calderone Glacieret (Gran Sasso d’Italia, Italy)

Ice is a rich reservoir of past climate information, and the well-documented increasing rate of glacier retreat represents a great loss for paleoclimate studies. In this framework, the Ice Memory project aims to extract and analyze ice cores from glacier regions worldwide and store them in Antarctica as a heritage record for future generations of scientists. Ice coring projects usually require a focused geophysical investigation, often based on Ground Penetrating Radar (GPR) prospecting to assess the most suitable drilling positions. As a novel approach in the Calderone Glacieret, we integrated the GPR method with Frequency Domain Electromagnetic (FDEM) surveys, a technique not commonly applied in the glacial environment. We used a separated-coils FDEM instrument to characterize the glacieret structure. The acquired FDEM datasets were inverted and compared to the GPR data and borehole information. The results demonstrated the capability of the FDEM technique to define the structure of the glacieret correctly; therefore, the potential to be applied in frozen subsoil environments. This opens new perspectives for the use of the FDEM technique to characterize periglacial environments, such as rock glaciers, where the coarse-blocky surface hinders data acquisition and enhances the problem of signal scattering.

The potential for palaeoseismic and palaeoclimatic reconstructions from Lake Tennyson, North Canterbury, New Zealand

ABSTRACT Lake Tennyson’s basin and sedimentary record were assessed for multiple branches of paleoenvironmental research. A geophysical investigation of the lake depositional setting was supported by physical and chemical analysis of multiple sediment cores. The basin reaches 60 m depth and several subaerial landforms identified were likely deposited from seismic activity. Deformed sediments and turbidites in gravity cores are attributed to one or more large (pre)historic earthquakes, and episodic grain size changes in sediment cores are related to either seismic and/or climatic/meteorological processes. A hummocky slump deposit located on the western lake bed margin is linked to widespread sediment deformation that was likely caused by movement of the Awatere Fault. Radiocarbon dating constrains the most recent major deformation event between the late thirteenth century CE and mid-twentieth Century. Folded turbidites in the stratigraphy suggest multiple sedimentary deformation episodes occurred during the last millennium. Micro-XRF elemental signatures suggest proxies of past water column mixing (windiness proxy) can be reconstructed via identification of changing redox conditions. Records from Lake Tennyson show potential for several palaeoenvironmental research applications, and combining them with basin morphostratigraphy and land-based palaeoclimate and palaeoseismic evidence can enhance understanding of environmental change in the northern South Island.

A preliminary geophysical investigation of lead mineralization in parts of the crystalline basement complex of Nigeria

A preliminary geophysical investigation of lead mineralization in parts of the crystalline basement complex of Nigeria

Delineation of groundwater potential zones in northern Omdurman area using electrical resistivity method

This study is conducted in the northern Omdurman area to delineate groundwater potential zones using electrical resistivity method. Omdurman is the most ancient city known as the historical capital of Sudan. Geoelectric survey employing vertical electrical sounding (VES) technique is carried out to explore the availability of groundwater in the study area. The measurements were conducted using Schlumberger configuration. In this study, twelve VES points are measured along four profiles. The measured data is processed and interpreted using 1D geophysical inversion technique constrained by lithological data obtained from two boreholes. The integration of electrical and geological data led to a reliable interpretation of the geophysical model. The obtained results revealed that the geological succession of the study area is mainly composed of five layers of recent deposits, clay, sandy clay, silicified and ferruginous sandstone, and sandstone. According to the resulting hydrogeological sections, the water-bearing formation is composed mainly of coarse sandstone and varies in thickness under confined conditions. The geoelectrical sounding method successfully fulfilled the aims of the study. Nevertheless, detailed hydrogeological and geophysical investigations need to be carried out for a comprehensive characterization of the groundwater aquifer.

SLF/ELF Fields From VED Solved by Normalized Spherical Harmonic Functions

AbstractElectromagnetic (EM) fields excited by a vertical electric dipole (VED) at the super‐low frequency and the extremely low frequency have been widely used in different studies such as space weather, earthquake predictions, geophysical investigations, and communications. Accurate and efficient algorithms are necessary for quick estimations of worldwide EM fields. This study proposes a recursive algorithm to calculate EM fields excited by a VED embedded in a layered spherical model. A set of local/general reflection and transmission coefficients is defined to describe propagations of EM fields in each spherical layer and the outgoing‐type waves and the standing‐type waves of EM fields are expressed by normalized spherical Bessel/Hankel functions. The normalized spherical Bessel/Hankel functions are not only useful to overcome the overflow problem in calculations of spherical Bessel/Hankel functions but also helpful to speed up the convergence of summation expressions of EM fields, because the normalized spherical Bessel/Hankel functions mitigate small oscillations terms. Calculating the primary fields and the secondary fields of the total EM fields, respectively, is also helpful to reach convergent summations, because their convergence radiuses are different.

New Insights from Legacy Seismic Data regarding Basalt Elevations and Variability on the Hanford Site

Abstract Migration of groundwater contaminants in the Gable Gap area of the Hanford Site in southeastern Washington State is strongly influenced by the distribution and permeability of basalts that lie beneath an unconfined aquifer. Locally, folding and faulting of the Columbia River Basalt associated with the Yakima fold and thrust belt followed by erosion due to the Lake Missoula floods resulted in a complex basalt surface that represents either an impermeable lower boundary to the unconfined aquifer system or localized regions of increased permeability that potentially promote communication between the unconfined aquifer system and deeper, confined aquifer systems. Paleo-channels carved into the basalt by floodwaters are thought to provide preferential flow paths for groundwater contaminants. In 2011, a seismic landstreamer campaign was carried out to image the basalt surface and produced pre-stack depth migrated p-wave reflection images. The reflection images identified two large troughs that may represent paleo-channels and several areas of possible faulting. Here, the streamer data are re-analyzed using refraction travel-time and Rayleigh wave dispersion analyses to obtain images of compressional and shear wave velocities within the suprabasalt sediment sections and the upper basalt surface. The combined interpretation of reflection and seismic velocity images shows complexity in the basalt velocity and elevation, which varies by 50 m or more within the study area. These results, along with other ongoing geophysical investigations, will be used to inform the site geologic model and potentially guide placement of future boreholes needed to quantify vertical flow between the confined and unconfined aquifers.

Reassessment of Geophysical Investigation of Zinc(Z), Cupper (Cu) and Lead (Pb) Potential Mineralization Deposits using Aeromagnetic Data in Wase Middle Benue Trough, Nigeria

Abstract: This effort aims to delineate structures responsible for exploring mineral resources in the Wase middle Benue trough area of Northcentral, Nigeria by evaluating the aeromagnetic data over that region. Oasis Montaj version 6.4 was used to qualitatively and quantitatively evaluate the aeromagnetic data. Techniques for Source Parameter Imaging (SPI) interpretation, including First Vertical Derivative, Analytical Signal, Upward Continuation, and Tilt Derivative, were used in the study. Analytic signal and tilt derivative maps showed different patterns of magnetic signatures independent of magnetization direction with amplitude ranging from 0.1 to 0.2nT/m and -1.3 to 1.4nT/m. They also showed qualitative interpretation applied aids enhance linear features at the expense of deep intrusive bodies like lineaments, fractures, and fault zones which trend Northeast Southwest (NE- SW) in the map of the study area. The boundaries of the geologically interesting anomalies were noticeably accentuated by the upward continuation done at 2 km. Nonetheless, this provides an approximation of the depth of the source of magnetic signatures in the area. The depth measured by SPI ranged from 103.9 to 1473.0 m. In the Eastern and Western regions of the region, respectively, shallow and deep-seated bodies are seen. The depth of the analysis was about 2000m, in conclusion, it was believed that the linear characteristics in the area that are trending northeast to southwest are possible structures for the prospecting of mineral deposits like zinc, copper, and lead

Delineation of aquifer promising zones and protective capacity for regional groundwater development and sustainability

Water security is the central mission of the sustainable development goals. The demand for potable and clean water has skyrocketed due to frequent borehole failures and population expansion, which requires adequate groundwater resource management strategies. Identifying groundwater potential zone, overburden protective index capacity and installations of alternative/artificial storage support mechanisms for water security and sustainability under the growing water challenge and demand is critical. This study identifies; (i) aquifer promising zones (ii) aquifer protective capacity through geophysical investigation and suggests (iii) improving aquifer recovery management strategy as the top three targets for groundwater development. An electric resistivity technique was applied to acquire a total of sixty (60) vertical electrical sounding points with Schlumberger arrays. The study indicates the resistivity layer of the aquifer unit ranges from 21 to 294 Ωm, while the aquifer layer thickness values spread from 8 to 59 m and the overburden thickness overlays the aquifer unit extends from 3 to 20 m. The deeper aquifer zones were encountered between 30 and 59 m, which could be suitable for groundwater development, and the shallow aquifer occurs between 8 and 14 m, which is not encouraging for groundwater development and may be susceptible to surface contaminations. However, for water security and sustainability, multiple boreholes should be sited at the delineated aquifer promising zone where the aquifer is fractured and occurs within a depth of 30 m and above. The weathered/fractured units constitute the regional aquifer units, which are largely responsible for the groundwater potential. The hydraulic conductivity of the regional aquifer was estimated to vary between 0.337 and 10.62 m/day, which invariably enhances the aquifer recovery processing. Groundwater quality and the risk of surface contamination were examined through overburden protective index capacity.

Incorporating geotechnical and geophysical investigations for underground obstruction detection: A case study

Determining the location and boundary of underground obstructions and/or anomalies is a common problem and often a great challenge for tunneling and underground construction. In this study, geotechnical investigations (penetration tests and borehole drilling/sampling) and geophysical investigations (surface wave method and cross-hole seismic method) were conducted with the aim of identifying the location and boundary of rock obstructions in Changi East, Singapore. The surface wave method is frequently used in the sites with lateral homogeneity in previous studies, but its application in the sites with rock obstructions is rare. The experimental results of this study indicate that the surface wave method is also able to determine the upper surface of rock obstructions, but difficult to identify the lateral and bottom boundaries of rock obstructions. To improve the precision of detection, the full waveform inversion (FWI) method was used to process the data from the cross-hole seismic survey. The results indicate that the inversion precision of P-wave is higher than that of S-wave. The horizontal and vertical ranges of rock obstructions in the P-wave inversion results are 14–26 m and 7.5–11.0 m respectively, roughly consistent with the results of penetration tests (about 15–25 m) and borehole log (8.85–10.80 m). This result proves that the sequential application of first-arrival time analysis and FWI can effectively delineate the boundary of rock obstructions. Finally, the results of various detection methods were analyzed and compared in this study. Considering the advantages of various methods, we propose a cost-effective and high-precision workflow containing both geotechnical and geophysical investigations.

PERL: a dataset of geotechnical, geophysical, and hydrogeological parameters for earthquake-induced hazards assessment in Terre del Reno (Emilia-Romagna, Italy)

Abstract. In 2012, the Emilia-Romagna region (Italy) was struck by a seismic crisis characterized by two main shocks (ML 5.9 and 5.8) which triggered relevant liquefaction events. Terre del Reno is one of the municipalities that experienced the most extensive liquefaction effects due to its complex geostratigraphic and geomorphological setting. This area is indeed located in a floodplain characterized by lenticular fluvial channel bodies associated with crevasse and levee clay–sand alternations, related to the paleo-Reno River. Therefore, it was chosen as a case study for the PERL project, which aims to define a new integrated methodology to assess the liquefaction susceptibility in complex stratigraphic conditions through a multi-level approach. To this aim, about 1800 geotechnical, geophysical, and hydrogeological investigations from previous studies and new realization surveys were collected and stored in the PERL dataset. This dataset is here publicly disclosed, and some possible applications are reported to highlight its potential.

Three thousand years of anthropogenic impact and water management and its impact on the hydro-ecosystem of the Mérantaise river, Paris conurbation (France)

This article assesses the long-term hydro-sedimentary and ecological consequences of the urban pressure around Paris over the last 3000 years on the Mérantaise river. Using a geoarchaeological approach combining sedimentological, geochemical, palynological and geophysical investigations enabled us to identify the transformations of the hydrosystem and to discuss the consequences of the different types of pressure and to put the role of biophysical and historical legacies into perspective with respect to contemporary dynamics. Using two study sites, one a former pond (Mérancis), the other a former mill site (Ors mill), nine cores, two auger holes and four trenches dug in the valley floor and two electrical resistivity tomography (ERT) profiles, it was possible to reconstruct the geometry of the sedimentary deposits. Chronostratigraphy was based on 41 radiocarbon dates and the history of vegetation and anthropogenic activities was reconstructed from 42 pollen samples and non-pollen palynomorphs collected from the former pond site. Despite the expansion of wetlands in the valley bottom, the pollen data revealed strong agropastoral activities and cereal growing in the Iron Age and up until the end of the Middle Ages. For the first time, sedimentological data associated with pollen data revealed hemp retting activities from c. 675 CE. From the Late Middle Ages onwards, water management led to the creation of two ponds to feed water mills. Despite the persistence of wetlands, this study highlights the early onset of anthropogenic modifications and in particular, the start of organic pollution and eutrophication in the Early Middle Ages, attesting to early eutrophication of water quality and aquatic environments resulting from the transformation of agropastoral practices and hydraulic pressure around the largest European city during the last 1500 years, well before the inset of urban sprawl in the watershed.

Assessment of the Nubian aquifer characteristics by combining geoelectrical and pumping test methods in the Omdurman area, Sudan

The recent research is carried out to model the characteristics and productivity of the groundwater aquifer in the Omdurman area, Sudan, by combining electrical resistivity and pumping test methods. Omdurman is the most populous city known as the traditional capital of Sudan. Vertical electrical sounding (VES) survey using Schlumberger array is carried out along four profiles to delineate the potential groundwater zones. Application of 1D geophysical inversion revealed five geoelectric layers, including recent deposits, clay, silicified and ferruginous sandstone, and sandstone. Additionally, based on the outcome of VES inversion, Dar Zarrouk parameters, including transverse resistance and longitudinal conductance, were calculated to model the aquifer characteristics. The transverse resistance ranged from 5587 to 309,853 Ωm2, while the longitudinal conductance varied between 0.14 and 2.5 Ω−1. The hydraulic conductivity and transmissivity are further measured using the VES data, ranging from 1.4 to 5.2 m/d and 435 to 1564 m2/day, respectively. The step-drawdown pumping tests were performed to evaluate the aquifer characteristics and thus validate the result of the geoelectrical method. The transmissivity obtained from the step test varied between 583 and 1226 m2/day, showing an acceptable agreement with those of geoelectrical data. Based on the measured parameters, the aquifer is classified as highly productive and ideal for groundwater development. The step drawdown test was further used to assess the performance of groundwater wells. The results indicated that faulty well design and inappropriate pumping rates influence some wells in the study area, resulting in high drawdown and low well efficiency. Overall, the objectives of the study were successfully achieved; nonetheless, detailed hydrogeological and geophysical investigations are recommended for comprehensive evaluation of the groundwater aquifer.

Hydrogeological characterization of the Complex Terminal aquifer using geoelectrical investigation in the arid environment of Chetma-Biskra (South-East of Algeria)

As a transition hydrogeological area, Biskra (Algeria) holds large groundwater resources in deeply buried aquifers such as the Complex Terminal. Due to a growing demand of drinking water supply and irrigation combined to low recharge, this arid region is facing an acute shortage of water and hence, the need for groundwater investigation. We used an integrated approach including geophysical investigation correlated to the geological and hydrogeological context in the Chetma area. The results highlight a deep structural form with significant hydrogeological features. In fact, two resistant limestone anticlines called Droh corresponding to a piezometric dome and a syncline filled with conductive deposit materials were identified. The Maastrichtian formation, consisting of fractured limestone, about 200 to 350 m thick, together with Lower Eocene marl limestone and limestone form a complex aquifer. At more than 400 m depth, boreholes capturing Maastrichtian limestone offer a high yield ranging from 25 to 90 L/s. Moreover, groundwater yield provides an average of 40 L/s at 300 m of depth. In contrast, synform geometries with high clay and marl content offer a weak groundwater yield. We confirmed the occurence of fractured aquifers which could constitute potentially groundwater production zones. This study provides new insights to enhance groundwater pumping for domestic and irrigation purposes for 2030.

Methods of Pulse Neutron Probing in Geological and Geophysical Investigations

. The problem of introducing pulse neutron probing in the process of geological and geophysical studies has been updated. The main factors that increase the sensitivity and information content of pulse methods in comparison with stationary neutron methods have been considered. It has been shown that the efficiency of pulse neutron probing depends on the length of the probe, time and energy characteristics of the equipment used. The principal features of various modifications of pulse neutron probing for solving geological and geophysical problems have been noted. The aspects of the efficient use of pulse modification in neutron gamma-ray spectrometry and inelastic scattering of fast neutrons have been discussed. Improved modifications of neutron probing based on the complex application of instrumental signals arising from inelastic scattering of fast and radiative capture of thermal neutrons have been proposed

Geophysical architecture of tectonized volcanic bodies near flysch thrust fronts (Outer Western Carpathians)

Teschenite association rocks (TAR) represent a specific type of mostly alkaline igneous rocks which form an almost 100 km long belt of discontinuous rock bodies within the Outer Western Carpathians (OWC) in the territory of Czechia and Poland. At present, a detailed mineralogical, geochemical, and stratigraphic analysis or dating of the volcanic formations is available, but basic structural and spatial relations characterizing TAR bodies and their origin are missing due to the poor exposure of TAR and lack of borehole data. A drill-hole- and outcrop-data-calibrated geophysical survey has proven to be a powerful tool for the interpretation of spatial extent and subsurface structure of TAR. At two type localities of TAR in Czechia (sites Staré Město and Bruzovice), a geophysical investigation combining ground conductivity mapping (CM) with profile measurement of electrical resistivity tomography (ERT), gravity survey, and magnetic survey was performed. A joint interpretation of the geophysical data served to determine the spatial extent (up to 500 m long and 40 m deep), geometry, and structural features (often fault-bounded with highly anisotropic heterogeneous structure of mélange character) of the studied TAR bodies. The interpreted magmatism of the study area included a stage of intrusion and extrusion of magmatic bodies in the Early Cretaceous, followed by a phase of fold-thrust deformation during the tectonic shortening of the area from the Late Cretaceous to Oligocene times. The resulting highly anisotropic rock mass consisting of TAR and its country rocks structurally controls the subsequent post-tectonic gravity-driven deformation.

A numerical assessment of variable saturation of the upper layers on the ground borne vibrations from underground trains: A case history

Ground borne vibrations generated by the passage of underground trains may change over time due to objective causes, such as increasing weight and speed of trains or ageing of the infrastructure components, as well as a variation in the dynamic response of the soil surrounding the tunnel. Among the possible causes of changes in the soil dynamic response, its hydrologic state has been seldom investigated. In this contribution, the role played by the conditions of the soil above the water table is addressed, starting from a case history in the city of Milano. Two-dimensional plane strain numerical models have been developed for the infrastructure. The models were calibrated on the results of two geophysical investigations performed at the same site in the city centre, but at two different times, which allowed distinguishing different dynamic responses. The system was excited by a synthetic load time history, matching a reference dynamic load spectrum included in Italian recommendations. Limitations of using this input on a 2D plane strain model were assessed by comparing the computed vibrations with experimental acceleration records collected on the tunnel. The results of the two numerical models are compared with those of a simulation performed assuming fully dry conditions above the water table. Overall, the set of analyses shows that even small changes in the dynamic response of the soil, interpretated as a consequence of variable saturation, may result in a change of a few decibels in the acceleration levels. Much larger accelerations are predicted on average with the simpler dry model, clearly showing the advantages of a more accurate modelling strategy.

Gravity Modeling to Understand the Subsurface Geology of the Central Part of West Bandung Regency (Citatah Karst Area, Cipatat-Padalarang)

Understanding the subsurface system of the central part of West Bandung Regency (including Karst Area), Indonesia, is an important undertaking carried out by geological and geophysical investigations. This research aims to identify geological subsurface features, especially faults,that have an impact on geohazards in the area. To achieve this goal, deep analysis of geology, geomorphology, and geophysical data is conducted. The central part of West Bandung regency is crossed by the Cimandiri Fault, which is located east of the transitional zone between the frontal subduction of Java and the oblique subduction of Sumatra. The preliminary result shows that the active fault has an impact on geohazards (earthquakes and landslides) in the area. Gravity reduction, regional and residual separation, as well as forward modeling with the Pluoff Equation, are all parts of the examination of the gravity data. A second-order polynomial trend surface was subtracted from the entire Bouguer gravity grid to create the residual gravity anomaly map. The amplitudes of the anomalies range from −12 to 8 mGal. The density distribution from the inverse calculation using 4 horizontal line sections (AB, CD, EF, and GH) was set up in the range of −0.3 to +0.3 g/cc. Geological surface markers for the model can be correlated with the information from the Cianjur Sheet geological map. Regional structure is also interpreted in the model to show the main structure of the reverse fault in the study area. HIGHLIGHTS The gravity method using density properties can provide good information about the subsurface karst system Modeling data gravity contributes to an understanding of geological subsurface interpretation Identifying geological subsurface features, especially faults that cause earthquakes and trigger landslides, is part of geohazard mitigation GRAPHICAL ABSTRACT

New Insights into the Internal Structures and Geotechnical Rock Properties of the Giant San Andrés Landslide, El Hierro Island, Spain

The San Andrés landslide on El Hierro (Canary Islands) represents a rare opportunity to study an incipient volcanic island flank collapse with an extensive onshore part. The presented research improves the knowledge of the internal structure and rock characteristics of a mega-landslide before its complete failure. The investigation combines multiple geophysical measurement techniques (active and passive seismic) and remotely sensed, high spatial resolution surveys (unmanned aerial vehicle) with in situ and laboratory geotechnical descriptions to characterize the rock properties inside and outside the San Andrés landslide. The available geophysical and geological data have been integrated into 3D geomodels to enhance their visual interpretation. The onshore geophysical investigations helped detect the possible San Andrés landslide sliding surfaces at depths between 320 m and 420 m, with a rather planar geometry. They also revealed that rocks inside and outside of the landslide had similar properties, which suggests that the previous fast movements of the landslide did not affect the bulk properties of the displaced rocks as the failure chiefly occurred along the weakened sliding plane. Uniaxial strength tests on basalt rocks further indicate a high variability and spatial heterogeneity of the rock strength properties due to the different types of volcanic rocks and their texture. The new information on the rock properties and structural setting of the San Andrés landslide can now be used to develop realistic geotechnical slope models of the onshore part of the flank collapse that are possibly applicable for slope stability or deformation calculations. It will also help assess related hazards marked by a low occurrence probability and a high impact potential.

Studying The Boundaries of The Tectonic Zones South of Latitude 32◦ of Iraq Using Trend Surface Analysis method

A geophysical study investigation was conducted in the southern part of Iraq bounded by coordinates; longitudes (39◦ - 48◦) East and latitude (29◦ - 32◦) North. This study includes analysis and interpretation of the potential data (gravity and magnetic) derived from the Bouguer anomaly map and Aeromagnetic total field intensity map of Iraq both of them is within the scale of (1: 1,000,000) and do comparison with the information available from geological maps, which include Tectonic, Hydrological and Geological information. Gravity and Magnetic maps of the study area were digitized at a grid interval of (1×1) cm which is equivalent to (10×10) km on the land. The trend surface technique was applied on the Bouguer anomaly map of the area. Through these analyses there are three tectonic boundaries have been proposed (A, B, and C). Results were compared with potential analyses of available geological information which match some faults proposed through data analysis with other geological information.