scholarly journals INTERPRETASI STRUKTUR BAWAH PERMUKAAN GUNUNG MURIA MENGGUNAKAN ANALISA DATA GRAVITASI

2012 ◽  
Author(s):  
Nasrun Balulu
Keyword(s):  
Horizontal Plane ◽  
Gravity Data ◽  
Continuation Method ◽  
Bouguer Anomaly ◽  
Research Area ◽  
Differential Method ◽  
Subsurface Geology ◽  
Global Positioning ◽  
Volcanic Processes ◽  
Equivalent Mass

A geophysical survey using gravity method was carried out in Muria  volcano. This research aimed to interpret the subsurface geology condition of the research area based on gravity data analysis. Research area is (47,6 x 45) km2    with 222 observation  points. Gravitymeter  LaCoste &amp; Romberg type G-1118 MVR was used to    measure the  gravity field, and differential method of Global Positioning System (GPS) was used to measure the position and elevation.<br /><br />Data processing was performed to gain complete Bouguer  anomaly of both residual and  regional. Bouguer density using graphical method resulted to the value of 2.67 gr/cm3.  Transformation to a horizontal plane was performed obtain by using equivalent mass method with horizontal level’s height of 1602 meters beyond the spheroid reference and equivalent The separation of regional anomaly and residual  anomaly  was  generated  through  upward  continuation  method  and  resulted  to  regional anomaly in the height of  15000 meters up the spheroid reference. The residual anomaly acquired by subtract the regional anomaly toward the complete Bouguer anomaly in a horizontal plane.<br /><br />The subsurface modelling of Muria  volcano and its surrounding was acquired from  Grav2DC for Windows. The result shows that Muria volcano and its surrounding was regionally controlled by rock resulted from volcanic processes as lava (density 2,91 gr/cm3). This volcanic rock due to the gravity collapse performed a caldera filled by andesit (density 2,58 gr/cm3). Another rock which is deposited in  Muria  volcano  are  tuff  from  Muria  Tuff  (density  2,4  gr/cm3),  tuff  sandstone  from  Patiayam formation (density 2,5 gr/cm3),  limestone from Bulu formation (density 2,7 gr/cm3), and  limestone from Ngrayong formation (density 2,8 gr/cm3).<br /><br />Keywords:Bouguer anomaly, Regional anomaly, Residual anomaly,  Modeling, Subsurface stracture.<br /><br />

scholarly journals Modeling Folding Zone in Kedungsari Compassionate Area Kulon Progo Yogyakarta with Gravity Method

2017 ◽  
Vol 1 ◽  
pp. 19-22
Author(s):  
Maya Luthfiya ◽  
Thaqibul Fikri Niyartama
Keyword(s):  
Data Reduction ◽  
Horizontal Plane ◽  
Gravity Data ◽  
Continuation Method ◽  
Bouguer Anomaly ◽  
Research Area ◽  
Quantitative Interpretation ◽  
Gravity Method ◽  
Local Anomaly ◽  
Andesitic Rock

This study aims to determine the condition of subsurface by doing interpretation quantitatively. Quantitative interpretation is done by modeling to determine the shape and boundary of the anomaly. The gravity data reduction is done up to Complete Bouguer Anomaly (CBA) value is obtained. The complete Bouguer anomaly is brought to horizontal plane reduction and separation of local and regional anomalies using the upward continuation method. 2.5 modelling has been made from local anomaly data to illustrate the subsurface condition of the research area more clearly. The result shows R1 density value of 2.55 g / m3 which is a limestone and R2 2,8902 g/m3 which is andesitic rock. The position of the anticline axis is at coordinates 49 S 9128700 N 409844.9 E, while the syncline axis is at coordinates 9129037 N 408694,1 E.

INTERPRETASI BAWAH PERMUKAAN GUNUNG ANAK RANAKAH DENGAN PEMODELAN DUA DIMENSI (2D) BERDASARKAN DATA ANOMALI GRAVITASI LOKAL

2018 ◽  
Vol 3 (1) ◽  
pp. 54-58
Author(s):  
Godensius Tematur ◽  
Jehunias L. Tanesib ◽  
Redi K. Pingak
Keyword(s):  
Continuation Method ◽  
Atmospheric Correction ◽  
Bouguer Anomaly ◽  
Geophysical Research ◽  
Subsurface Geology ◽  
Dimensional Modeling ◽  
Free Air ◽  
Geological Conditions ◽  
Free Air Anomaly ◽  
Surrounding Areas

ABSTRAK Penelitian geofisika dengan menggunakan metode gravitasi telah dilakukan di Gunung Anak Ranakah dan sekitarnya di kabupaten Manggarai Nusa Tenggara Timur pada bulan Juni sampai dengan bulan Juli 2016. Penelitian ini bertujuan untuk mengetahui kondisi geologi bawah permukaan daerah penelitian dengan menggunakan data anomali udara bebas dari Sandwell dan Smith 2016. Data tersebut direduksi dengan koreksi atmosfer, koreksi Bouguer Sederhana, dan koreksi kurvatur hingga memperoleh anomali Bouguer Lengkap. Data anomali Bouguer dibawa ke bawah bidang topografi dengan metode kontinuasi ke bawah sedalam 300 m menggunakan program Magpic. Selanjutnya dilakukan pemodelan 2 dimensi menggunakan program Grav2DC. Hasil yang diperoleh menunjukkan bahwa kondisi geologi bawah permukaan gunung Anak Ranakah dan Sekitarnya didominasi oleh batuan basalt (densitas 2,70 -3.30 ), andesit (densitas 2.4 -2.8 ), dan soil (densitas 1.2 -2.40 ). Kata kunci: Anomali Gravitasi, Pemodelan 2D, Gunung Anak Ranakah ABSTRACT Geophysical research by using the gravity method has been carried out on the Ranakah child mountain and surrounding areas in Manggarai Regency of East Nusa Tenggara in June until July 2016. This research aims to know the condition of the subsurface geology of the area of research using the free air anomaly data from Sandwell and Smith 2016. The data are reduced by atmospheric correction, Simple Bouguer correction, and the correction of curvature to obtain complete Bouguer anomalies. Bouguer anomaly data brought down the field topography with continuation method down as deep as 300 m using the Magpic. Then, 2 dimensional modeling is done using the Grav2DC. The results obtained show that the geological conditions under the surface of the Ranakah Child mountaoin and its surrounding area was dominated by basalt rocks (density of ), andesite (density of ), and soil rocks (density of ). Keywords: Gravity Anomaly, 2D Modelling, Ranakah child Mountain.

scholarly journals Studi Identifikasi Struktur Geologi Bawah Permukaan Untuk Mengetahui Sistem Sesar Berdasarkan Analisis First Horizontal Derivative (FHD), Second Vertical Derivative (SVD), Dan 2,5D Forward Modeling Di Daerah Manokwari Papua Barat

2020 ◽  
Vol 4 (2) ◽  
pp. 62-76
Author(s):  
Shiska Yulistina
Keyword(s):  
Cross Section ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Forward Modeling ◽  
Research Area ◽  
Geological Structure ◽  
North West ◽  
Vertical Derivative ◽  
Horizontal Derivative ◽  
Papua Barat

In general, Manokwari has a geological structure that is in the form of a folding area found in the highlands of the mountains. Among the creases, there is a fault up and the fault down. In coastal or marine areas found many reefs and corals. The study of gravity was conducted in the Manokwari area of West Papua with the aim to know the subsurface geological structures based on FHD (First Horizontal Derivative), SVD (Second Vertical Derivative) and 2.5D Forward Modeling on the residual anomaly maps of the study area. The results showed that the research area has Bouguer Anomaly value ranged from 4 mGal to 96 mGal with the low anomaly at the left side of the research area lengthwise relatively in north-west to south-east direction, the middle-value anomaly spreads in the west-east area of research area, high anomaly scattered in the northern part of the research area. The results of the 2.5D subsurface modeling and the SVD and FHD analysis indicated the presence of a Thrust Fault on the C-C’ cross-section, on the B-B’ cross-section there is a Diorite Lembai intrusion with the density value is 2.75 gr/cc, whereas the A-A' cross-section which intersects with Sorong fault were not found any fault or rock intrusion based on observed gravity data of the research area.

scholarly journals INTERPRETATION OF BOUGUER ANOMALY TO DETERMINE FAULT AND SUBSURFACE STRUCTURE AT BLAWAN-IJEN GEOTHERMAL AREA

2016 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Anjar Pranggawan Azhari ◽  
Sukir Maryanto ◽  
Arief Rachmansyah
Keyword(s):  
Horizontal Plane ◽  
Hot Springs ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Normal Fault ◽  
Reverse Fault ◽  
Geothermal Area ◽  
Magma Intrusion ◽  
Main Fault ◽  
Fall Deposits

Gravity survey has been acquired by Gravimeter Lacoste &amp; Romberg G-1035 at Blawan-Ijen geothermal area. It was a focusing study from previous research. The residual Bouguer anomaly data was obtain after applying gravity data reduction, reduction to horizontal plane, and upward continuation. Result of Bouguer anomaly interpretation shows occurrence of new faults and their relative movement. Blawan fault (F1), F2, F3, and F6 are normal fault. Blawan fault is main fault controlling hot springs at Blawan-Ijen geothermal area. F4 and F5 are oblique fault and forming a graben at Banyupahit River. F7 is reverse fault. Subsurface model shows that Blawan-Ijen geothermal area was dominated by the Ijen caldera forming ignimbrite (ρ1=2.670 g/cm3), embedded shale and sand (ρ2=2.644 g/cm3) as Blawan lake sediments, magma intrusion (ρ3=2.814 g/cm3 &amp; ρ7=2.821 g/cm3), andesite rock (ρ4=2.448 g/cm3) as geothermal reservoir, pyroclastic air fall deposits (ρ5=2.613 g/cm3) from Mt. Blau, and lava flow (ρ6=2.890 g/cm3).

scholarly journals PEMODELAN 3D STRUKTUR BAWAH PERMUKAAN GUNUNGAPI AGUNG PROVINSI BALI MENGGUNAKAN METODE GAYA BERAT

2020 ◽  
Vol 5 (2) ◽  
pp. 68-75
Author(s):  
Nasyratul Ilmi ◽  
Karyanto Karyanto
Keyword(s):  
Magma Chamber ◽  
Bouguer Anomaly ◽  
Research Area ◽  
3D Modelling ◽  
Contour Map ◽  
Magma Flow ◽  
Qualitative And Quantitative ◽  
Subsurface Geology ◽  
Derivative Analysis ◽  
Data Processing Methods

Under surface structure, 3d modelling of Agung volcano in Bali had been conducted by using gravity methods. This research aims to identify the magma chamber and make a model below the surface of the Great Volcano of Bali Province by using gravity anomaly data. Data processing methods performed in this research were consists of six steps: (i) arrangement the contour map of Bouguer anomaly, (ii) spectrum analysis, (iii) anomaly regional and residual separation, (iv) Second Vertical Derivative analysis, (v) cross-section of subsurface geology construction by using 3D (inverse modelling), (vi) qualitative and quantitative interpretation. Anomaly Bougeur contour map result shows the value of Bouguer anomaly in research area around 84 mGal spreading around west-south part of research point until 279 mGal on Agung volcano body. Anomaly regional value is around 97 mGal to 253 mGal. The boundary between basement a sedimentary rock of the research area are at the depth of 0,89 km. The magma chamber of Agung volcano is in the depth of 500 to 8000 metres to a form of towing up and polluted in the middle. The density of the magma chamber is around 2,73 until 2,86 gr/cc. The magma flow in the Agung volcano of visible at the depth of 0 metres.

scholarly journals PEMODELAN DAN ANALISA STRUKTUR BAWAH PERMUKAAN DAERAH PROSPEK PANASBUMI KEPAHIANG BERDASARKAN METODE GAYABERAT

2020 ◽  
Vol 4 (2) ◽  
pp. 47-61
Author(s):  
Roy Bryanson Sihombing ◽  
Rustadi Rustadi
Keyword(s):  
Gravity Data ◽  
Bouguer Anomaly ◽  
Research Area ◽  
Inverse Modelling ◽  
3D Inversion ◽  
Vertical Derivative ◽  
The North ◽  
A Value ◽  
Value Range ◽  
Range Of Values

Research has been conducted in Kepahiang area using gravity data with the aim of identify faults based on analysis of the Second Vertical Derivative (SVD) and interpreting structure sub-surface of the based on 3D inverse modelling from Bouguer anomaly and residual anomaly. The research area have an Bouguer anomaly between 38 mGal - 74 mGal, where the high Bouguer anomaly value has a value range of 63,2 mGal - 74 mGal located in the southwest direction of the research area. Whereas the low Bouguer anomaly value has a range of values 38 mGal - 47 mGal located in the north of the research area. To know the existence of fault structure in research area, conducted filtering Second Vertical Derivative (SVD) on the map Bouguer anomaly, regional and residual. The structure faulting is shown with contour of zero and between the contours of high and low. From the analysis of SVD complete anomaly Bouguer and SVD residual anomaly there are 8 (eight) faulting, while from SVD regional anomaly there are 4 (four) fault. 3D inversion modeling of the residual anomaly was done to prove the existence of the fault analyzed based on filtering Second Vertical Derivative (SVD). Based on the results of inversion 3D residual anomaly been gained one (1) reservoir in a northern direction research area and two (2) in the direction of west the research area by a contrast the density of -0,0719356 gr/cc until -0,236053 gr/cc with a depth of 0 meters up to 4.705 meters.

Optimal Density Determination of Bouguer Anomaly Using Fractal Analysis (Case of study: Charak area,IRAN)

2005 ◽  
Vol 1 (1) ◽  
pp. 21-24
Author(s):  
Hamid Reza Samadi
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Fractal Analysis ◽  
Fractal Geometry ◽  
Host Rock ◽  
Bouguer Anomaly ◽  
Research Area ◽  
Density Difference ◽  
Optimal Density

In exploration geophysics the main and initial aim is to determine density of under-research goals which have certain density difference with the host rock. Therefore, we state a method in this paper to determine the density of bouguer plate, the so-called variogram method based on fractal geometry. This method is based on minimizing surface roughness of bouguer anomaly. The fractal dimension of surface has been used as surface roughness of bouguer anomaly. Using this method, the optimal density of Charak area insouth of Hormozgan province can be determined which is 2/7 g/cfor the under-research area. This determined density has been used to correct and investigate its results about the isostasy of the studied area and results well-coincided with the geology of the area and dug exploratory holes in the text area

Application of gravity and magnetic methods to assess geological hazards and natural resource potential in the Mosida Hills, Utah County, Utah

Geophysics ◽  
2000 ◽  
Vol 65 (5) ◽  
pp. 1514-1526 ◽  
Author(s):  
Alvin K. Benson ◽  
Andrew R. Floyd
Keyword(s):  
Gravity Data ◽  
Magnetic Data ◽  
Geological Hazards ◽  
Mafic Lava ◽  
Subsurface Geology ◽  
Gravity And Magnetic ◽  
Geophysical Surveys ◽  
Utah County ◽  
Gravity And Magnetic Data ◽  
Hills Area

Gravity and magnetic data were collected in the Mosida Hills, Utah County, Utah, at over 1100 stations covering an area of approximately 58 km2 (150 mi2) in order to help define the subsurface geology and assess potential geological hazards for urban planning in an area where the population is rapidly increasing. In addition, potential hydrocarbon traps and mineral ore bodies may be associated with some of the interpreted subsurface structures. Standard processing techniques were applied to the data to remove known variations unrelated to the geology of the area. The residual data were used to generate gravity and magnetic contour maps, isometric projections, profiles, and subsurface models. Ambiguities in the geological models were reduced by (1) incorporating data from previous geophysical surveys, surface mapping, and aeromagnetic data, (2) integrating the gravity and magnetic data from our survey, and (3) correlating the modeled cross sections. Gravity highs and coincident magnetic highs delineate mafic lava flows, gravity lows and magnetic highs reflect tuffs, and gravity highs and magnetic lows spatially correlate with carbonates. These correlations help identify the subsurface geology and lead to new insights about the formation of the associated valleys. At least eight new faults (or fault segments) were identified from the gravity data, whereas the magnetic data indicate the existence of at least three concealed and/or poorly exposed igneous bodies, as well as a large ash‐flow tuff. The presence of low‐angle faults suggests that folding or downwarping, in addition to faulting, played a role in the formation of the valleys in the Mosida Hills area. The interpreted location and nature of concealed faults and volcanic flows in the Mosida Hills area are being used by policy makers to help develop mitigation procedures to protect life and property.

scholarly journals Geometrical Characterisation of the Mamfe Basin, Cameroon, from the Earth, Gravitational Model (EGM 2008)

2018 ◽  
Vol 7 (1) ◽  
pp. 94
Author(s):  
Anatole Eugene Djieto Lordon ◽  
Mbohlieu YOSSA ◽  
Christopher M Agyingi ◽  
Yves Shandini ◽  
Thierry Stephane Kuisseu
Keyword(s):  
Average Length ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Igneous Rocks ◽  
Average Depth ◽  
The Earth ◽  
Gravitational Model ◽  
Petroleum Generation ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

Gravimetric studies using the ETOPO1-corrected high resolution satellite-based EGM2008 gravity data was used to define the surface extent, depth to basement and shape of the Mamfe basin. The Bouguer anomaly map was produced in Surfer 11.0. The Fast Fourier Transformed data was analyzed by spectral analysis to remove the effect of the regional bodies in the study area. The residual anomaly map obtained was compared with the known geology of the study area, and this showed that the gravity highs correspond to the metamorphic and igneous rocks while the gravity lows match with Cretaceous sediments. Three profiles were drawn on the residual anomaly map along which 2D models of the Mamfe basin were drawn. The modeling was completed in Grav2dc v2.06 software which uses the Talwini’s algorithm and the resulting models gave the depth to basement and the shape of the basement along the profiles. After processing and interpretation, it was deduced that the Mamfe basin has an average length and width of 77.6 km and 29.2 km respectively, an average depth to basement of 5 km and an overall U-shape basement. These dimensions (especially the depth) theoretically create the depth and temperature conditions for petroleum generation. 

scholarly journals Lineament Extraction using Gravity Data in the Citarum Watershed

2021 ◽  
Vol 53 (1) ◽  
Author(s):  
Gumilar Utamas Nugraha ◽  
Karit Lumban Goal ◽  
Lina Handayani ◽  
Rachmat Fajar Lubis
Keyword(s):  
Gravity Data ◽  
Bouguer Anomaly ◽  
High Density ◽  
Low Density ◽  
Residual Value ◽  
Satellite Gravity ◽  
Structural Weakness ◽  
Major Trend ◽  
Lineament Extraction ◽  
Butterworth Filters

Lineament is one of the most important features showing subsurface elements or structural weakness such as faults. This study aims to identify subsurface lineament patterns using automatic lineament in Citarum watershed with gravity data. Satellite gravity data were used to generate a sub-surface lineament. Satellite gravity data corrected using Bouguer and terrain correction to obtain a complete Bouguer anomaly value. Butterworth filters were used to separate regional and residual anomaly from the complete Bouguer anomaly value. Residual anomaly gravity data used to analyze sub-surface lineament. Lineament generated using Line module in PCI Geomatica to obtain sub-surface lineament from gravity residual value. The orientations of lineaments and fault lines were created by using rose diagrams. The main trends observed in the lineament map could be recognized in these diagrams, showing a strongly major trend in NW-SE, and the subdominant directions were in N-S. Area with a high density of lineament located at the Southern part of the study area. High-density lineament might be correlated with fractured volcanic rock upstream of the Citarum watershed, meanwhile, low-density lineament is associated with low-density sediment. The high-density fracture might be associated with intensive tectonics and volcanism.

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