Prediksi Model 2d Data Magnetotelurik Terbaik Berdasarkan Pendekatan Model Irisan Di Cekungan Tomori dan Sekitarnya

2019 ◽  
Vol 20 (4) ◽  
pp. 225
Author(s):  
Gusti Muhammad Lucki Junursyah ◽  
Dimas Bagus Maulana ◽  
Randi Rusdiana
Keyword(s):  
Earth Model ◽  
Magnetotelluric Data ◽  
2D Modeling ◽  
Geological Interpretation ◽  
Angle Rotation ◽  
2D Data ◽  
Surrounding Areas ◽  
Overlay Model ◽  
Strike Angle ◽  
Model Approach

2D modeling of magnetotelluric data produce various models that are influenced by noise and differences in coordinate measurement systems with strike directions, so the results are inaccurate. A technique that can be done to identify the accuracy of the data is the rotation analysis based on the overlay model approach. The type of rotation used are strike angle and fix angle. The strike angle rotation is done by maximizing the anti-diagonal impedance value, while the rotation fix angle refers to the isotropic homogeneous earth model by eliminating the static effect on the surface. The overlay model approach is based on the assumption that the distribution of resistivity variations of the rock in the subsurface has same value in various models. 2D modeling used in this analysis consists of three trajectories of correlation results from 30 magnetotelluric measurement points in the Tomori and surrounding areas. The results of the analysis show that the strike angle rotation model is the best model that can be used in the study area with the approach of determination value reaches 0.7735, therefore it can reduce subsurface geological interpretation deviation based on various 2D models.Keywords: Magnetotelluric, impedance rotation, strike angle rotation, fix angle rotation

scholarly journals Prediksi Model 2d Data Magnetotelurik Terbaik Berdasarkan Pendekatan Model Irisan Di Cekungan Tomori dan Sekitarnya

2019 ◽  
Vol 20 (4) ◽  
pp. 225
Author(s):  
Gusti Muhammad Lucki Junursyah ◽  
Dimas Bagus Maulana ◽  
Randi Rusdiana
Keyword(s):  
Earth Model ◽  
Magnetotelluric Data ◽  
2D Modeling ◽  
Geological Interpretation ◽  
Angle Rotation ◽  
2D Data ◽  
Surrounding Areas ◽  
Overlay Model ◽  
Strike Angle ◽  
Model Approach

2D modeling of magnetotelluric data produce various models that are influenced by noise and differences in coordinate measurement systems with strike directions, so the results are inaccurate. A technique that can be done to identify the accuracy of the data is the rotation analysis based on the overlay model approach. The type of rotation used are strike angle and fix angle. The strike angle rotation is done by maximizing the anti-diagonal impedance value, while the rotation fix angle refers to the isotropic homogeneous earth model by eliminating the static effect on the surface. The overlay model approach is based on the assumption that the distribution of resistivity variations of the rock in the subsurface has same value in various models. 2D modeling used in this analysis consists of three trajectories of correlation results from 30 magnetotelluric measurement points in the Tomori and surrounding areas. The results of the analysis show that the strike angle rotation model is the best model that can be used in the study area with the approach of determination value reaches 0.7735, therefore it can reduce subsurface geological interpretation deviation based on various 2D models.Keywords: Magnetotelluric, impedance rotation, strike angle rotation, fix angle rotation

scholarly journals 2D Modeling of Seulawah Agam Geothermal Field Based on Magnetotelluric (MT) Data

2019 ◽  
Vol 8 (2) ◽  
pp. 61-65
Author(s):  
Irfan Putra ◽  
Nazli Ismail ◽  
Marwan Marwan
Keyword(s):  
Geothermal Field ◽  
Magnetotelluric Data ◽  
2D Modeling ◽  
Te Mode ◽  
Tm Mode ◽  
Top Soil ◽  
Resistivity Variation ◽  
2D Data ◽  
Mode Tm ◽  
2D Resistivity

Telah dilakukan pemodelan 2D data Magnetotellurik (MT) di Gunung Api Seulawah Agam. Penelitian ini bertujuan untuk mendapatkan model konseptual lapangan panas bumi Gunung Api Seulawah Agam berdasarkan model resistivitas 2D. Data fungsi transfer MT yang digunakan yaitu dari rentang frekuensi 2,34 - 320 Hz yang terdiri dari 7 titik stasiun pengukuran. Data titik pengukuran terdiri dari nilai intensitas medan listrik dan intensitas medan magnet yang memiliki 28 frekuensi. Total panjang lintasan pengukuran yaitu sepanjang 27,7 km. Lintasan pengukuran memotong Gunung Api Seulawah Agam dari arah Selatan ke Utara. Data hasil pengukuran yaitu berupa nilai resistivitas semu dan fase yang kemudian dimodelkan menggunakan kode REBOCC. Terdapat 3 model yang dihasilkan dari proses inversi data MT menggunakan REBOCC yaitu mode TE, mode TM dan mode TE+TM. Model mode TE+TM merupakan model yang paling bagus karena menghasilkan model yang lebih jelas dan smooth bila dibandingkan dengan model pada mode TE dan mode TM. Hasil model konseptual menunjukkan bahwa pada lapisan pertama yaitu lapisan top soil (lapisan teratas) memiliki nilai resistivitas sebesar 20 - 60 Ω.m, yang terdapat pada jarak 6 - 23 km. Lapisan kedua yaitu lapisan clay/caprock dengan nilai resistivitas relatif rendah yaitu lebih kecil dari 10 Ω.m, yang berada pada jarak 6 - 27,7 km. Lapisan clay/caprock memiliki sifat impermeabel dan konduktif. Selanjutnya lapisan ketiga yaitu lapisan reservoir dengan nilai resistivitas berkisar antara 10 - 100 Ω.m. 2D modeling of magnetotelluric data has been conducted at Seulawah Agam volcano. This study aims to obtain a conceptual model of Seulawah Agam geothermal field based on 2D resistivity model. The magnetotelluric data were measured in range of frequency from 2.34 to 320 Hz at 7 stations along a profile crossing the Seulawah Agam volcano. The length of the profile is 27.7 km with a direction from north to south. The apparent resistivity and phase of magnetotelluric transfers function were used for the 2D inversion modelling of REBOCC code. The inversion was carried out using TE-mode, TM-mode and TE+TM-mode to obtain a better model. The model inverted of TE+TM-mode has resolved well, resistivity variation of subsurface of the Seulawah Agam volcano area. The inverted model shows the top later has resistivity values from 20-60 Ω.m, which is interpreted as a top soil. The second layer is a layer of clay/caprock with a relatively low resistivity values of less than 10 Ω.m. The third layer is predicted as reservoir with resistivity values ranging between 10-100 Ω.m. Keywords: magnetotelluric method, resistivity, 2D model, REBOCC code and Volcano Seulawah Agam.

scholarly journals Geological interpretation of the 2008 seismic reflection, refraction and magnetotelluric data from the northern Eyre Peninsula, Gawler Craton

2010 ◽  
Vol 2010 (1) ◽  
pp. 1-4 ◽  
Author(s):  
R.J. Korsch ◽  
G.L. Fraser ◽  
R. Dutch ◽  
N.L. Neumann ◽  
R.S. Blewett ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Magnetotelluric Data ◽  
Geological Interpretation

Bayesian inversion of CSEM and magnetotelluric data

Geophysics ◽  
2012 ◽  
Vol 77 (1) ◽  
pp. E33-E42 ◽  
Author(s):  
Arild Buland ◽  
Odd Kolbjørnsen
Keyword(s):  
Prior Knowledge ◽  
Inversion Method ◽  
Earth Model ◽  
Magnetotelluric Data ◽  
Inversion Result ◽  
Electromagnetic Data ◽  
Magnetic Components ◽  
Resistivity Model ◽  
Frequency Components ◽  
Inversion Procedure

We have developed a Bayesian methodology for inversion of controlled source electromagnetic (CSEM) data and magnetotelluric (MT) data. The inversion method provided optimal solutions and also the associated uncertainty for any sets of electric and magnetic components and frequencies from CSEM and MT data. The method is based on a 1D forward modeling method for the electromagnetic (EM) response for a plane-layered anisotropic earth model. The inversion method was also designed to invert common midpoint (CMP)-sorted data along a 2D earth profile assuming locally horizontal models in each CMP position. The inversion procedure simulates from the posterior distribution using a Markov chain Monte Carlo (McMC) approach based on the Metropolis-Hastings algorithm. The method that we use integrates available geologic prior knowledge with the information in the electromagnetic data such that the prior model stabilizes and constrains the inversion according to the described knowledge. The synthetic examples demonstrated that inclusion of more data generally improves the inversion results. Compared to inversion of the inline electric component only, inclusion of broadside and magnetic components and an extended set of frequency components moderately decreased the uncertainty of the inversion. The results were strongly dependent on the prior knowledge imposed by the prior distribution. The prior knowledge about the background resistivity model surrounding the target was highly important for a successful and reliable inversion result.

scholarly journals Integrated Geophysical Evidence for the Middle-Lower Crust Melting of the Songpan-Aba Terrain, NE Tibetan Plateau

2021 ◽  
Vol 9 ◽  
Author(s):  
Chongjin Zhao ◽  
Luolei Zhang ◽  
Peng Yu ◽  
Xi Xu
Keyword(s):  
Tibetan Plateau ◽  
Magnetic Layer ◽  
Orogenic Belt ◽  
The Tibetan Plateau ◽  
The West ◽  
Magnetotelluric Data ◽  
West Qinling ◽  
The North ◽  
Weakly Magnetic ◽  
Surrounding Areas

The Songpan−Aba region is located on the northeastern edge of the Tibetan Plateau. Tectonically, the area is surrounded by the West Qinling orogenic belt in the north, the Longmenshan orogenic belt in the southeast, and the East Kunlun and Sanjiang orogenic belts in the west and southwest, forming a triangle that provides an ideal location to study the crust-mantle structure and deep tectonics of the eastward extrusion of the Tibetan Plateau. In this study, the magnetic and electrical structures of the Songpan−Aba area were investigated by inversion using high-precision magnetic anomaly and magnetotelluric data to obtain the subsurface magnetization inversion intensity and resistivity of Songpan–Aba and adjacent areas. The results revealed a continuous magnetic layer up to 20 km below Songpan–Aba and its surrounding areas in the south, possibly originating from a magma root southwest of the Longmenshan massif. In the West Qinling, Songpan–Aba, and Longmenshan areas, pervasive low-resistance, weakly magnetic, or magnetic layers were identified below 20 km that might be formed from the molten mantle material extruded from the eastern edge of the Tibetan Plateau.

scholarly journals Two-dimensional determinant inversion of marine magnetotelluric data and a field example from the Gulf of California, Mexico

Geophysics ◽  
2021 ◽  
Vol 86 (1) ◽  
pp. E37-E57
Author(s):  
Shunguo Wang ◽  
Steven Constable ◽  
Valeria Reyes-Ortega ◽  
Hormoz Jahandari ◽  
Colin Farquharson ◽  
...  
Keyword(s):  
Gulf Of California ◽  
Subduction Zones ◽  
Field Data ◽  
Real Data ◽  
Transverse Magnetic ◽  
Two Dimensional ◽  
Magnetotelluric Data ◽  
Earth Structures ◽  
3D Effects ◽  
2D Data

Two-dimensional marine magnetotelluric (MT) observations are useful for offshore geologic studies, such as natural resource exploration, fault mapping, fluid estimation at subduction zones, and the delineation of the lithosphere-asthenosphere boundary beneath the seafloor. Earth structures are often assumed to be two dimensional, which allows MT data to be decomposed into a transverse electric (TE) mode and a transverse magnetic (TM) mode. The 2D assumption can effectively reduce acquisition and computational costs. However, offline 3D effects and other problems such as lack/failure of the compass on instruments are often encountered, making it difficult to decompose data into the TE and TM modes. In these cases, 2D inversion may be misleading or may not provide an acceptable misfit to the marine MT observations. Thus, we have developed a 2D determinant inversion to the marine MT method to mitigate these difficulties, implemented in the MARE2DEM code, and we tested its utility using synthetic examples and a field example. In the synthetic examples, the determinant inversion demonstrates an ability to overcome 3D effects caused by 3D anomalies and bathymetry. With confidence from the synthetic tests, we interpreted real data acquired in the Gulf of California, Mexico, where not only is the bathymetry 3D in nature, but the external compasses failed to record the orientation. The field data can not only be fit to a reasonable misfit with a determinant inversion, but the resolved conductive zones also have a good correlation with known faults. A comparison between the resistivity model from the field data and a seismic reflection section shows that a previously interpreted fault, the Wagner Fault, should be shifted 5 km toward the southwest and made slightly steeper. Thus, the implementation of the determinant inversion may provide a new approach for using problematic 2D data.

Automatic 1-D inversion of magnetotelluric data: Finding the simplest possible model that fits the data

Geophysics ◽  
2000 ◽  
Vol 65 (3) ◽  
pp. 773-782 ◽  
Author(s):  
Laust B. Pedersen ◽  
Mehran Gharibi
Keyword(s):  
Plane Wave ◽  
Theoretical Data ◽  
Small Error ◽  
Earth Model ◽  
Model Parameters ◽  
Random Errors ◽  
Magnetotelluric Data ◽  
Near Surface ◽  
Resolution Power ◽  
Inversion Procedure

We demonstrate that automatic layered inversion of plane‐wave electromagnetic data can be carried out by modifying standard least‐squares inversion schemes. The modifications include a logarithmic reparameterization of the unknown model parameters, whereby all layer parameters are forced to remain within given bounds. However, the most important modification to help the optimization process find the best model and to avoid local minima is to split the data into several subbands, starting from the highest frequencies. By this stripping procedure, the shallower part of the model becomes well estimated first. As more data are introduced, more layers may be required to improve the data fit. The new inversion procedure has been applied to many sets of theoretical data representing increasingly complicated layering that is often found in near‐surface studies. The main result of these simulations is that there is a very strong coupling between the resolution power of plane‐wave data and their random errors. Particularly at small error levels around 1–2%, the resolution power increases greatly. For larger error levels the fine layering of the models becomes smeared, and only the variations in thickness of the upper layer can be resolved. A comparison with the popular “Occam” procedure shows, not unexpectedly, that a blocky earth is best represented by a blocky earth model rather than by a smooth model.

scholarly journals Economic Growth Modelling in West Nusa Tenggara Using Bayesian Spatial Model Approach

2021 ◽  
Vol 5 (1) ◽  
pp. 80
Author(s):  
Siti Soraya ◽  
Baiq Candra Herawati ◽  
Habib Ratu Perwira Negara
Keyword(s):  
Economic Growth ◽  
Spatial Dependency ◽  
Measuring Instrument ◽  
Goods And Services ◽  
The People ◽  
Spatial Approach ◽  
Total Labor ◽  
Surrounding Areas ◽  
Bayesian Spatial Model ◽  
Model Approach

Economic growth is a measure of the welfare of the people in an area. Economic movement is characterized by the number of goods and services produced. The high amount of goods produced and the services used are of course strongly influenced by the amount of available capital, the labor involved, and the level of technology used. The measuring instrument or a reflection of economic growth is the Gross Regional Domestic Product (GRDP). The purpose of this study is to model economic growth in NTB in 2018. In this study, GRDP modeling was carried out using the Bayesian Spatial approach. Based on the results of testing the spatial dependency and spatial heterogeneity, it shows that there is a spatial dependence on the GRDP of districts / cities in NTB Province.. From the analysis conducted, it was found that  was positive and insignificant at the 10% level. The parameter estimation results show that the number of workers, the value of capital and the number of workers weighed are variables that have a significant effect on the model. Thus the GRDP of an area in West Nusa Tenggara is influenced by the number of workers, the value of capital and the total labor weight and the GRDP of other surrounding areas.

scholarly journals Deep Structure of the Lithosphere in the Central Tien Shan along the Son-Kul Magnetotelluric Sounding Profile

2021 ◽  
Vol 496 (2) ◽  
pp. 101-106
Author(s):  
A. K. Rybin ◽  
E. A. Bataleva ◽  
V. E. Matiukov ◽  
Yu. A. Morozov ◽  
K. S. Nepeina
Keyword(s):  
Cross Section ◽  
Block Structure ◽  
Deep Structure ◽  
Tien Shan ◽  
Palm Tree ◽  
Localized Deformation ◽  
Magnetotelluric Data ◽  
Geological Interpretation ◽  
Quantitative Characteristics ◽  
Geological Substrate

Abstract New results of a detailed study of the deep structure of the Central Tien Shan along the Son-Kul magnetotelluric (MT) profile crossing the Son-Kul Lake are reported. Based on the results of magnetotelluric data modeling, the regional and local geoelectric anomalies in the lithosphere are studied and their quantitative characteristics are given. Geological interpretation of the geoelectric cross-section was carried out, which supported the existing ideas about the block–hierarchical structure of the upper part of the Earth’s crust. This corresponds to the tectonophysical concepts of the sequential inserted subordination of large and smaller elements of the zone–block structure consisting of stable blocks and limiting mobile zones, which are distinguished by the high dislocation of the geological substrate. The integral pattern of the distribution and morphology of zones of high electrical conductivity in this segment of the Central Tien Shan crust may reflect discretely localized palm tree–type structures associated with the evolution of transgressive suture zones of localized deformation during the Hercynian and Alpine tectogenesis.

scholarly journals Geological interpretation of the northern flank of the Matagami camp, Quebec, using gravity and magnetic inversions

2019 ◽  
Vol 56 (5) ◽  
pp. 471-482 ◽  
Author(s):  
Thibaut Astic ◽  
Michel Chouteau
Keyword(s):  
Gravity Data ◽  
Volcanic Rocks ◽  
Three Dimensional ◽  
Gravity Models ◽  
Earth Model ◽  
Surface Geometry ◽  
Northern Flank ◽  
Geological Interpretation ◽  
Geophysical Model ◽  
Gravity And Magnetic

The northern flank of the Galine anticline of the Matagami camp has been well known for decades for hosting polymetallic VMS deposits (mostly copper and zinc). In such an already explored area, sophisticated exploration tools must be used in the hope of generating new information. By integrating geophysical, petrophysical, and geological data into a three-dimensional (3D) common earth model to constrain gravity and magnetic inversions, our objective was to validate and improve the geological interpretations of the area and to highlight geophysical anomalies unexplained in the current geological model. Both 3D magnetic and gravity data inversions confirm the surface geometry and the steep dip of the geological units. The inverted gravity models indicate that units observable at the surface of the northern flank extend subvertically to several kilometres in depth. The pyroxenitic phase of the Bell River Complex is most certainly dipping steeply to the south, contrary to some surface measurements. The Olga pluton shows no significant decrease in width at depth, with the exception of the west end, which appears to be an apophysis. A major unknown mass, which may correspond to a synvolcanic mafic intrusion that is not outcropping, is revealed in the Allard River volcanic rocks. This improved geophysical model featuring geometrical constraints obtained by careful processing and inversion of the potential-fields data could contribute to new exploration targets.

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