scholarly journals Preliminary Study of Probolinggo Active Fault in East Java Based on Gravity Method

2021 ◽  
Vol 936 (1) ◽  
pp. 012025
Author(s):  
Juan Pandu Gya Nur Rochman ◽  
M.Singgih Purwanto ◽  
Anik Hilyah ◽  
F M. Haris Miftakhul ◽  
Mohamad Setyo Ari Nuswantara ◽  
...  
Keyword(s):  
Bouguer Anomaly ◽  
Normal Fault ◽  
Observation Point ◽  
Gravity Method ◽  
Subsurface Structures ◽  
The North ◽  
Free Air ◽  
Anomaly Map ◽  
Free Air Anomaly ◽  
Gravity Acceleration

Abstract The Gravity Method based on TOPEX satellite data is a one of geophysical method which from satellite observations. The gravity method investigate the gravitational field from one to another observation point. The principle of this method has the ability to distinguish the mass material density from its environment, so that the subsurface structure can be identified. In this research, gravity method is used to identify subsurface structures that are suspected of Probolinggo Fault and identify the rock lithology. From TOPEX we get free air anomaly and then applied the correction process to obtain Complete Bouguer Anomaly (CBA) value. The CBA value is processed interpolation to create CBA map, and then the map is filtered by butterworth to obtain regional and residual maps. The value of high gravity acceleration is 0.076 - 19.74 mGal indicating compact rocks. Meanwhile, based on the residual anomaly map, the value of smaller gravity acceleration is -0.92 - 0.9 mGal indicates lower compacting rocks with smaller mass. The gravity acceleration contrast on the residual anomaly, on the north side of fault line (0.12 mGal to 0.45 mGal) and on the south side (-0.92 mGal to -0.043 mGal), is interpreted as normal fault. Furthermore, 3D modelling shows density value less than 2 gr/cm3 we can interpret as pyroclastic fall, in between 2 gr/cm3 until 2.4 gr/cm3 is sandstone and more than 2.4 gr/cm3 is igneous rock such as andesit. 2D slicing modelling show presence the shear fault, so we can suspect this area have oblique fault with west-east direction.

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 Identification of Subsurface Structures of Geothermal Potential Area in East of Mount Lawu Using The Gravity Method

2020 ◽  
Vol 10 (01) ◽  
pp. 65
Author(s):  
Sorja Koesuma ◽  
Mela Budiani Septianingsih ◽  
Budi Legowo
Keyword(s):  
Volcanic Rocks ◽  
Bouguer Anomaly ◽  
Research Area ◽  
Earth’S Gravity Field ◽  
Gravity Method ◽  
Subsurface Structures ◽  
Eastern Flank ◽  
Free Air ◽  
Geothermal Potential ◽  
Terrain Corrections

<p>Information about the eastern side subsurface stones of Mount Lawu regarding geothermal potential is limited. This research was conducted to provide information regarding geothermal potential in those area by using the gravity method. We did a 18 sites of gravity surveys in eastern flank of Mount Lawu where located in Magetan regency, Ngawi regency and Sragen regency, East Java. The principle of this method is to measure the earth's gravity field, then the value of gravity is corrected by some gravity corrections, i.e. height, tide, drift, normal gravity, free-air, Bouguer and terrain corrections. The Complete Bouguer Anomaly (CBA) shows the formation that related to the rock formation in the subsurface of Mount Lawu. Based on CBA modelling we found that in the eastern flank of Mount Lawu contains of tuff and breccia of volcanic rocks, breccia Jabolarangan and tuff Jabolarangan, lava andesite, igneous rock (pumice), and sedimentary rocks in the form of sandstone and clay. We found a fault structure on six tracks of a research area. Otherwise, we estimated that there is a geothermal potential on the southeast side of the research area</p>

Tectonic insight and 3-D modelling of the Lusi (Java, Indonesia) mud edifice through gravity analyses

2021 ◽  
Vol 225 (2) ◽  
pp. 984-997
Author(s):  
Álvaro Osorio Riffo ◽  
Guillaume Mauri ◽  
Adriano Mazzini ◽  
Stephen A Miller
Keyword(s):  
Risk Mitigation ◽  
Bouguer Anomaly ◽  
Geological Model ◽  
Resource Exploitation ◽  
Subsurface Structures ◽  
Central Java ◽  
Geostatistical Interpolation ◽  
Gravity Response ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

SUMMARY Lusi is a sediment-hosted hydrothermal system located near Sidoarjo in Central Java, Indonesia, and has erupted continuously since May 2006. This mud eruption extends over a surface of ∼7 km2, and is framed by high containment dams. The present study investigates the geometry of the subsurface structures using a detailed gravimetric model to visualize in 3-D the Lusi system and surrounding lithologies. The obtained residual Bouguer anomaly map, simulated through geostatistical interpolation methods, supports the results of previous deformation studies. The negative gravity anomaly zones identified at Lusi are interpreted as fractured areas through which fluids can ascend towards the surface. A 3-D detailed geological model of the area was constructed with Geomodeller™ to highlight the main features. This model relies on the structures’ density contrasts, the interpreted residual Bouguer anomaly map, and geological data from previous authors. 3-D algorithms were used to calculate the gravity response of the model and validate it by inverse methods. The final output is a gravity constrained 3-D geological model of the Lusi mud edifice. These results provide essential details on the Lusi subsurface and may be useful for possible future geothermal resource exploitation and for the risk mitigation plans related to the maintenance of the man-made framing embankment.

Free Air Anomaly Map of Canada from Piece-Wise Surface Fittings Over Half-Degree Blocks

1973 ◽  
Vol 27 (4) ◽  
pp. 293-300 ◽  
Author(s):  
Dezsö Nagy
Keyword(s):  
Gravity Anomaly ◽  
Extreme Values ◽  
Free Air ◽  
Equivalent Length ◽  
Order Polynomial ◽  
Standard Deviations ◽  
Anomaly Map ◽  
Half Degree ◽  
Free Air Anomaly ◽  
Polynomial Surface

The region of Canada, which has been covered by gravity surveys (including 1970 data), has been subdivided into 2,923 surface elements of sides of a half-degree along the meridian and approximately equivalent length along the parallels. The gravity anomaly at the center of each element was estimated by fitting a low-order polynomial surface to the free air anomalies within each element. The extreme values are —160 and 96 milligals, with over 85 per cent of the anomalies being in the range of —40 and 20 milligals. About two thirds of all computed anomalies are estimated to have standard deviations less than ±10 milligals.

A Gravity Investigation of the Pickwell Down Sandstone, North Devon

1967 ◽  
Vol 104 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Hamid Nassar Al-Sadi
Keyword(s):  
Bouguer Anomaly ◽  
Gravity Gradient ◽  
Near Surface ◽  
Red Sandstone ◽  
Residual Gravity ◽  
The North ◽  
Thrust Plane ◽  
Residual Gravity Anomaly ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

AbstractThe area to the north of Barnstaple (North Devon) was covered by a detailed gravity survey. The main gravity gradient of the Bouguer anomaly map (estimated to be 1·2 mgals per mile) confirmed the conclusions drawn by Bott et al. (1958), who attributed it to a basin of possibly Carboniferous sediments and/or Old Red Sandstone, about 4 miles thick, separated from the outcropping Devonian rocks by an assumed thrust plane.A negative residual gravity anomaly is located over the outcrop of the Pickwell Down Sandstone. Analyses of the anomaly show that it is caused by the southwards dipping belt of sandstone and that the angle of dip of the formation decreases with depth. At a depth of about 2 miles the formation becomes nearly horizontal. Alternatively, it may terminate against an assumed thrust plane underlying the whole outcropping Devonian.The aeromagnetic map of the area shows an elongated magnetic “high” following the outcrop of the Morte Slates. The anomaly is probably caused by near surface, highly magnetized rocks in association with the Morte Slates.

Processing steps for the compiling AAGRG gravity maps

2020 ◽  
Author(s):  
Pavol Zahorec ◽  
Juraj Papčo ◽  
Roman Pašteka ◽  
Keyword(s):  
Gravity Data ◽  
Atmospheric Correction ◽  
Bouguer Anomaly ◽  
Taylor Series Expansion ◽  
Methodological Innovation ◽  
Atmospheric Effect ◽  
Free Air ◽  
Point Data ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

&lt;p&gt;First unified complete Bouguer anomaly map of AlpArray area compiled from terrestrial gravity data is in preparation. The following steps to calculate the first version of the map were performed: 1. unification of different spatial, height and gravity systems, 2. getting available detailed (mainly LiDAR-based) elevation models and their transformation from physical to ellipsoidal heights, 3. calculation of mass corrections (gravity effect of the topography between the surface and ellipsoid level) with density 2 670 kg/m&lt;sup&gt;3&lt;/sup&gt;, 4. calculation of bathymetric corrections for water masses below the ellipsoid (correction density -1&amp;#160;640 kg/m&lt;sup&gt;3&lt;/sup&gt;), 5. calculation of lake correction for great alpine lakes (correction density -1&amp;#160;670 kg/m&lt;sup&gt;3&lt;/sup&gt;), 6. calculation of the final complete Bouguer anomalies based on normal field (Somigliana formula with GRS80 parameters, free-air correction using Taylor series expansion to the 2&lt;sup&gt;nd&lt;/sup&gt; order) and particular corrections including also the atmospheric correction.&lt;/p&gt;&lt;p&gt;The quality control of input data was performed based on the height differences between the point data and particular elevation models. Several thousand points with height residuals higher than chosen threshold (&amp;#177;50 m) were excluded. The available detailed local elevation models (resolution 10 &amp;#8211; 20 m) were compared with global model MERIT (resolution 25 m).&lt;/p&gt;&lt;p&gt;The most significant methodological innovation is the ellipsoidal heights concept using straightforward calculation of mass/bathymetric corrections in respect to the ellipsoid instead of using the geophysical indirect effect computation. Our specially developed program Toposk was used for mass/bathymetric correction calculation (the standard distance of 166.7 km was used for the first version of the map) as well as for the calculation of lake corrections. Mass corrections amount to hundreds of mGal, while the lake corrections reach more than 5 mGal locally. Atmospheric effect taking into account topography was also calculated and compared with standard atmospheric correction.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

A new look at Belgian aeromagnetic and gravity data through image-based display and integrated modelling techniques

1993 ◽  
Vol 130 (5) ◽  
pp. 583-591 ◽  
Author(s):  
B. C. Chacksfield ◽  
W. De Vos ◽  
L. D'Hooge ◽  
M. Dusar ◽  
M. K. Lee ◽  
...  
Keyword(s):  
Large Scale ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Digital Processing ◽  
Integrated Modelling ◽  
Magnetic Data ◽  
Gravity Gradient ◽  
The North ◽  
Anomaly Map ◽  
Shaded Relief

AbstractDigital processing and image-based display techniques have been used to generate contour and shaded-relief maps of Belgian aeromagnetic data at a scale of 1:300000 for the whole of Belgium. These highlight the important anomalies and structural trends, particularly over the Brabant Massif. North and vertically illuminated shaded-relief plots, enhanced structural belts trending west–east to northwest–southeast in the Brabant Massif and west–east to southwest–northeast in the core of the Ardennes. The principal magnetic lineaments have been identified from the shaded-relief plots and tentatively correlated to basement structures. Most short lineaments are correlated with individual folds while the more extensive lineaments are correlated with large scale fault structures. Magnetic highs within the Brabant Massif are attributed to folded sediments of the Tubize Group. The magnetic basement in the east of Belgium is sinistrally displaced to the north by an inferred deep NNW–SSE crustal fracture. The Bouguer anomaly map of Belgium identifies the Ardennes as a negative area, and the Brabant Massif as a positive area, with the exception of a WNW–trending gravity low in its western part. The southern margin of the Brabant Massif is defined by a steep gravity gradient coincident with the Faille Bordiere (Border Fault). Trial modelling of the gravity and magnetic data, carried out along profiles across the Brabant and Stavelot massifs, has identified probable acid igneous intrusions in the western part of the Brabant Massif, and a deep magnetic lower density body underlying the whole Ardennes region, which is thought to be a distinctive Precambrian crustal block.

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