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 & 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 & 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).

Forward modeling of gravity data using geostatistically generated subsurface density variations

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. G81-G94 ◽  
Author(s):  
Geoff Phelps
Keyword(s):  
Gravity Data ◽  
Solution Space ◽  
Cumulative Effect ◽  
Normal Fault ◽  
Gravity Anomalies ◽  
Reverse Fault ◽  
Heterogeneous Distribution ◽  
Geostatistical Models ◽  
Air Force Base ◽  
Models Of Gravity

Using geostatistical models of density variations in the subsurface, constrained by geologic data, forward models of gravity anomalies can be generated by discretizing the subsurface and calculating the cumulative effect of each cell (pixel). The results of such stochastically generated forward gravity anomalies can be compared with the observed gravity anomalies to find density models that match the observed data. These models have an advantage over forward gravity anomalies generated using polygonal bodies of homogeneous density because generating numerous realizations explores a larger region of the solution space. The stochastic modeling can be thought of as dividing the forward model into two components: that due to the shape of each geologic unit and that due to the heterogeneous distribution of density within each geologic unit. The modeling demonstrates that the internally heterogeneous distribution of density within each geologic unit can contribute significantly to the resulting calculated forward gravity anomaly. Furthermore, the stochastic models match observed statistical properties of geologic units, the solution space is more broadly explored by producing a suite of successful models, and the likelihood of a particular conceptual geologic model can be compared. The Vaca Fault near Travis Air Force Base, California, can be successfully modeled as a normal or strike-slip fault, with the normal fault model being slightly more probable. It can also be modeled as a reverse fault, although this structural geologic configuration is highly unlikely given the realizations we explored.

scholarly journals Tectonic and Hydrothermal Activities in Debagh, Guelma Basin (Algeria)

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Said Maouche ◽  
Abdeslam Abtout ◽  
Nacer-Eddine Merabet ◽  
Tahar Aïfa ◽  
Atmane Lamali ◽  
...  
Keyword(s):  
Field Study ◽  
Active Fault ◽  
Hot Springs ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Hydrothermal Activity ◽  
Structural Features ◽  
Tectonic Activity ◽  
Hydrothermal Activities ◽  
Field Geology

Quaternary and Pliocene travertines, deposited from hot springs, can reveal much about neotectonic and hydrothermal activity. The aim of this work is the understanding of the actual tectonic activity in the Guelma Basin and in one of its spa structures. Gravity data were collected during a field study in the Hammam Debagh (HD) area and then analyzed to better highlight the architecture of its subsurface underlying structures. This analysis was performed by means of a Bouguer anomaly, upward continuations, and residual and derivative maps. Comparison of gravity maps, field geology, geomorphic observations, and structural maps allowed us to identify the major structural features in the Hammam Debagh. As a result, we confirm the position of the Hammam Debagh active fault which is superimposed to the hydrothermal active source in the NW-SE direction characterized by a negative gravity anomaly.

scholarly journals Gravity anomaly to identify Walanae fault using second vertical derivative method

2018 ◽  
Vol 2 (1) ◽  
pp. 34
Author(s):  
Marsellei Justia ◽  
Muhammad Fikri H Hiola ◽  
Nur Baiti Febryana S
Keyword(s):  
Gravity Data ◽  
Moving Average ◽  
Normal Fault ◽  
Reverse Fault ◽  
The South ◽  
Vertical Derivative ◽  
The North ◽  
Free Air ◽  
Free Air Anomaly ◽  
Fault Mechanism

<p class="Abstract">Research has been conducted to identify the Walanae Fault, coordinates 4–6 S and 118-120 E using anomalous gravity data. This research uses data measurement of Topography and the Free Air Anomaly from the TOPEX/Poseidon satellite. Then the authors processed to obtain the bouguer anomalies and made modeling by using the Surfer 10. The authors used the Second Vertical Derivative (SVD) with filter Elkins of Moving Average then analyze the graph of the SVD. The results shows the value of the residual anomaly in the north of fault is 25.21 mGal, in the middle occur range 17.67 mGal to 24.98 mGal and 30,376 mGal in the south of fault. The authors indicates the existence of a difference between the gravity between the Walanae Fault with surrounding geologic. From these results also show that Walanae Fault has a reverse fault mechanism in the northern part and the normal fault mechanism in the middle to the south, the authors conclude that the Walanae Fault is divided into two segments, that is the northern and the southern segment.</p>

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.

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 Gravity Anomaly in Kelud, Kasinan-Songgoriti, and Arjuno-Welirang Volcano Hosted Geothermal Area, East Java, Indonesia

2020 ◽  
Vol 9 (3S) ◽  
pp. 172-176
Keyword(s):  
Data Analysis ◽  
Gravity Anomaly ◽  
3D Modeling ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Geothermal Area ◽  
Geothermal Systems ◽  
Free Air ◽  
Relationship Of ◽  
The Relationship

This study aims to determine the relationship of heat reservoirs in the Kelud, Kasinan-Songgoriti, and Arjuno-Welirang geothermal systems based on gravity data analysis. Gravity data are obtained from Geodetic Satellite (GEOSAT) and European Remote Sensing-1 (ERS-1) Satellite which have been corrected to free air correction. The result of gravity data analysis is in the form of a complete Bouguer anomaly which represents the gravity anomaly below the surface. The results of the complete Bouguer anomaly value obtained were -15,238 mGal to 86,087 mGal. Based on these results, regional anomalies and residual anomalies will be separated to determine the depth of the two anomalies. 3D modeling was carried out based on the complete Bouguer anomaly data to determine the reservoir relationships in the Kelud, Kasinan-Songgoriti, and Arjuno-Welirang geothermal systems.

scholarly journals STUDI POTENSI MIGAS DENGAN METODE GAYABERAT DI LEPAS PANTAI UTARA JAKARTA

2016 ◽  
Vol 8 (1) ◽  
pp. 23
Author(s):  
Saultan Panjaitan ◽  
Nyoman Astawa
Keyword(s):  
Gravity Anomaly ◽  
Oil And Gas ◽  
Bouguer Anomaly ◽  
Normal Fault ◽  
Reservoir Rock ◽  
Reverse Fault ◽  
High Gravity ◽  
Low Gravity ◽  
Rock Density ◽  
Block Faulting

Anomali Bouguer dapat dibagi kedalam dua kelompok yaitu: Anomali gayaberat rendah terbentuk pada kisaran nilai 15 mGal hingga -40 mGal sebagai rendahan sinklin. Anomali gayaberat tinggi terbentuk pada kisaran nilai 40 mGal hingga 60 mGal sebagai tinggian antiklin. Formasi batuan dari atas hingga bawah sebagai berikut: Formasi Cisubuh rapat massa batuan 2.5 gr/cm³ ketebalan pada penampang ±1400 meter. Formasi Parigi rapat massa batuan 2.7 gr/cm³ ketebalan ± 400 meter. Formasi Cibulakan rapat massa batuan 2.6 gr/cm³ ketebalan ± 1600 meter. Formasi Jatibarang rapat massa 2.8 gr/cm³ ketebalan ± 1000 meter. Batuan reservoir didominasi lensa-lensa batupasir Formasi Cibulakan Atas, Cibulakan Bawah serta batugamping Formasi Parigi dan batupasir Formasi Talangakar. Batuan induk migas adalah serpih lakustrin halus Anggota Cibulakan Bawah (Formasi Talang Akar). Tinggian batuan reservoir pada anomali sisa antara 0 mGal hingga 16 mGal dan kedalaman pada penampang ± 1500 meter dengan rapat massa batuan 2.7 gr/cm³ Sesar normal terbentuk arah Utara-Selatan dan sesar naik arah Timur-Barat dikontrol oleh pematahan bongkah pada batuan alas metamorf dengan rapat massa 3.0 gr/cm³. Kata kunci: gayaberat, antiklin, anomali sisa, lepas pantai. Bouguer anomaly can be grouped into two parts: Low Gravity anomaly formed at 15 mGal to 40 mGal as syncline lower. High gravity anomaly formed at 40 mGal to 60 mGal as anticline high. Rock formation from the top to the bottom as follows: Cisubuh Formation rock of density with 2.5 gr / cm³ thickness at section of ± 1400 metre. Parigi Formation rock density of 2.7 gr / cm³ thicknees ± 400 metre. Cibulakan Formation density with 2.6 gr / cm³ thickness ± 1600 metre. Jatibarang Formation with density 2.8 gr / cm³ of thickness ± 1000 metre. Reservoir rock is dominated by lens of sandstone upper Cibulakan Formation, Lower Cibulakan and also Parigi Formation limestone and Talangakar Formation sandstone. Sourced rock of oil and gas from shales lacustrine of Cibulakan Lower or Talang Akar Formation. High Rocks reservoir at recidual anomaly range from 0 mGal to 16 mGal at section deepness ± 1500 metre with density of 2.7 gr / cm³, formed by normal fault of Northern-Southern direction and reverse fault Eastern-Western direction controlled by block faulting metamorphics bedrock with density of 3.0 gr / cm³. Keywords: gravity, anticline, recidual anomaly, offshore.

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 The impact of earthquakes on fluids in the crust

1994 ◽  
Vol 37 (6) ◽  
Author(s):  
G. C. P. King ◽  
R. M. Wood
Keyword(s):  
Water Discharge ◽  
Normal Fault ◽  
Reverse Fault ◽  
Crustal Rocks ◽  
Decay Times ◽  
Crystalline Crust ◽  
Chemical Behaviour ◽  
Deformation Models ◽  
Fault Displacement ◽  
The Impact

The character of the hydrological changes that follow major earthquakes has been investigated and found to be critically dependent on the style of fault displacement. In areas where fracture-flow in the crystalline crust communicates uninterrupted with the surface the most significant response is found to accompany major normal fault earthquakes. Increases in spring and river discharges peak a few days after the earthquake and typically excess flow is sustained for a period of 4 12 months. Rainfall equivalent discharges, have been found to ceed 100 mm close to the fault and remain above 10 mm at distances greater than 50 km. The total volume of water released in two M 7 normal fault earthquakes in the Western U.S.A. was 0.3-0.5 km3. In contrast, hydroIogical changes accompanying reverse fault earthquakes are either undetected or else involve falls in well-levels and spring-flows. The magnitude and distribution of the water-discharge for these events is compared with deformation models calibrated from seismic and geodetic information, and found to correlate with the crustal volume strain down to a depth of at least 5 km. Such relatively rapid drainage is only possible if the fluid was formerly contained in high aspect ratio fissures interconnected throughout much of the seismogenic upper crust. The rise and decay times of the discharge are shown to be critically dependent on crack widths, for which the «characteristic» or dominant cracks cannot be wider than 0.03 mm. These results suggest that fluid-filled cracks are ubiquitous throughout the brittle continental crust, and that these cracks open and close through the earthquake cycle. Seismohydraulic fluid flows have major implications for our understanding of the mechanical and chemical behaviour of crustal rocks, of the tectonic controls of fluid flow associated with petroleum migration, hydrothermal mineralisation and a significant hazard for underground waste disposal.

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