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 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 Geological Structure Analysis to Determine the Direction of the Main Stress at Western Part of Kolok Mudik, Barangin District, Sawahlunto, West Sumatera

2017 ◽  
Vol 2 (1) ◽  
pp. 46
Author(s):  
Miftahul Jannah ◽  
Adi Suryadi ◽  
Muchtar Zafir ◽  
Randi Saputra ◽  
Ihsanul Hakim ◽  
...  
Keyword(s):  
Structure Analysis ◽  
Normal Fault ◽  
Geological Structure ◽  
Reverse Fault ◽  
Geological Structures ◽  
The North ◽  
Main Stress

On the study area there are three types of structure, those are fault, fold and joint. Types of fault were found  in the study area, reverse fault with the strike/dip is N215oE/75o, normal fault has a fault directions N22oE and N200oE with pitch 35o, and dextral fault with pitch 10o and strike N219oE. Fold and joint structures used to determine the direction of the main stress on the study area. Further, an analysis used stereonet for data folds and joints. So that from the data got three directions of main stress, those are Northeast – Southwest (T1), North – South (T2) and Southeast – Northwest (T3). On the Northeast – Southwest (T1) stress there are four geological structures, anticline fold at ST.3 , syncline folds at ST. 13a, ST. 13b, ST. 13c and ST. 33, chevron fold at ST. 44 and joint at ST. 2. On the North – South (T2) stress there are three geological structures, those are syncline fold at ST. 35, anticline fold at ST. 54 and joints at ST. 41, ST. 46 and ST. 47. On the Southeast – Northwest (T3) stress were also three geological structures, those are chevron fold at ST 42a, overturned fold at ST. 42b, syncline fold at ST. 42c and joints at ST. 5 and ST. 34.

Airborne gravity measurements over mountainous areas by using a LaCoste & Romberg air‐sea gravity meter

Geophysics ◽  
2002 ◽  
Vol 67 (3) ◽  
pp. 807-816 ◽  
Author(s):  
Jérôme Verdun ◽  
Roger Bayer ◽  
Emile E. Klingelé ◽  
Marc Cocard ◽  
Alain Geiger ◽  
...  
Keyword(s):  
Data Reduction ◽  
Classical Method ◽  
Gravity Data ◽  
Airborne Gravity ◽  
Mountainous Area ◽  
Vertical Acceleration ◽  
Mountainous Areas ◽  
Free Air ◽  
Gravity Measurements ◽  
Free Air Anomaly

This paper introduces a new approach to airborne gravity data reduction well‐suited for surveys flown at high altitude with respect to gravity sources (mountainous areas). Classical technique is reviewed and illustrated in taking advantage of airborne gravity measurements performed over the western French Alps by using a LaCoste & Romberg air‐sea gravity meter. The part of nongravitational vertical accelerations correlated with gravity meter measurements are investigated with the help of coherence spectra. Beam velocity has proved to be strikingly correlated with vertical acceleration of the aircraft. This finding is theoretically argued by solving the equation of the gravimetric system (gravity meter and stabilized platform). The transfer function of the system is derived, and a new formulation of airborne gravity data reduction, which takes care of the sensitive response of spring tension to observable gravity field wavelengths, is given. The resulting gravity signal exhibits a residual noise caused by electronic devices and short‐wavelength Eötvös effects. The use of dedicated exponential filters gives us a way to eliminate these high‐frequency effects. Examples of the resulting free‐air anomaly at 5100‐m altitude along one particular profile are given and compared with free‐air anomaly deduced from the classical method for processing airborne gravity data, and with upward‐continued ground gravity data. The well‐known trade‐off between accuracy and resolution is discussed in the context of a mountainous area.

scholarly journals Oligocene-Miocene extension led to mantle exhumation in the central Ligurian Basin, Western Alpine Domain

2019 ◽  
Author(s):  
Anke Dannowski ◽  
Heidrun Kopp ◽  
Ingo Grevemeyer ◽  
Dietrich Lange ◽  
Martin Thowart ◽  
...  
Keyword(s):  
Gravity Data ◽  
Sedimentary Cover ◽  
Seafloor Spreading ◽  
Wide Angle ◽  
The South ◽  
Seismic Line ◽  
Acoustic Basement ◽  
North West ◽  
The North ◽  
Ligurian Basin

Abstract. The Ligurian Basin is located in the Mediterranean Sea to the north-west of Corsica at the transition from the western Alpine orogen to the Apennine system and was generated by the south-eastward trench retreat of the Apennines-Calabrian subduction zone. Late Oligocene to Miocene rifting caused continental extension and subsidence, leading to the opening of the basin. Yet, it still remains enigmatic if rifting caused continental break-up and seafloor spreading. To reveal its lithospheric architecture, we acquired a state of the art seismic refraction and wide-angle reflection profile in the Ligurian Basin. The seismic line was recorded in the framework of SPP2017 4D-MB, the German component of the European AlpArray initiative, and trends in a NE-SW direction at the centre of the Ligurian Basin, roughly parallel to the French coastline. The seismic data recorded on the newly developed GEOLOG recorder, designed at GEOMAR, are dominated by sedimentary refractions and show mantle Pn arrivals at offsets of up to 70 km and a very prominent wide-angle Moho reflection. The main features share several characteristics (i.e. offset range, continuity) generally associated with continental settings rather than documenting oceanic crust emplaced by seafloor spreading. Seismic tomography results are augmented by gravity data and yield a 7.5–8 km thick sedimentary cover which is directly underlain by serpentinised mantle material at the south-western end of the profile. The acoustic basement at the north-eastern termination is interpreted to be continental crust, thickening towards the NE. Our study reveals that the oceanic domain does not extend as far north as previously assumed and that extension led to extreme continental thinning and exhumation of sub-continental mantle which eventually became serpentinised.

Accumulation Models of the Oil Pools of Block XXI of Tamsag Basin in Mongolia

2014 ◽  
Vol 962-965 ◽  
pp. 522-525
Author(s):  
Liang Zhao
Keyword(s):  
Water Distribution ◽  
Physical Property ◽  
Reverse Fault ◽  
The South ◽  
Hydrocarbon Migration ◽  
The North ◽  
Oil Water ◽  
Migration Pathways

This document explains different tectonic styles and sedimentary fillings give rise to the different accumulation combinations and accumulation models between the south and the north frogs of East Subsag of South Buir Sag. The Tsagaantsav Formation oil pools, subject to the rupture of the fault-period tectonic layers, has developed multiple types of traps including reverse fault blocks, fault noses and drag anticlines. They are close to the oil-generating sags, in the indicator areas of hydrocarbon migration where hydrocarbon pools, particularly tectonic-controlled pools, are easily formed. The lithology and physical property play an important controlling role over the formation of oil pools with complicated oil-water distribution relationship. The constant and the late active ruptures as longitudinal hydrocarbon migration pathways, together with the sedimentary sands of multiple genesis types, have given shape to the multi-formation lithologic, lithologic-tectonic or tectonic accumulation combinations.

scholarly journals Control litológico y estructural de los deslizamientos en el monte Rodiles (Asturias, España) Lithological and structural control of landslides in the Rodiles Hill (Asturias, Spain)

2018 ◽  
Vol 36 (36) ◽  
pp. 279
Author(s):  
S. Llana Fúnez
Keyword(s):  
Structural Control ◽  
Thick Layer ◽  
Normal Fault ◽  
Reverse Fault ◽  
Cantabrian Mountains ◽  
The North ◽  
Jurassic Rock ◽  
Para Determinar ◽  
Historic Settlement ◽  
The Hill

Resumen: El monte Rodiles, situado en el margen oriental de la ría de Villaviciosa, conserva evidencias de ocupación histórica desde sus orígenes como castro romanizado. El asentamiento está limitado en su vertiente sur por los restos de una muralla defensiva, mientras que en la ladera nororiental existen escarpes rocosos que debieron de actuar como defensa del enclave. Este trabajo realiza un análisis del relieve y revisa la estructura del sustrato geológico en el entorno próximo para determinar el origen de los escarpes en la ladera nordeste. Los datos de campo y el análisis de la topografía permiten identificar la existencia de varios deslizamientos que afectan a gran parte de la ladera nororiental del monte Rodiles. La masa deslizada aprovecha la inclinación de la sucesión litológica del Jurásico hacia el NE. La existencia de un nivel de arcillas, mecánicamente incompetentes, por debajo de los conglomerados de la Formación La Ñora, mecánicamente más competentes, permite el movimiento de la ladera hacia el mar. Estos escarpes están además alineados con la terminación lateral de una falla normal Mesozoica reactivada posteriormente como una falla inversa durante el levantamiento de la Cordillera Cantábrica. Las cicatrices de los deslizamientos, desarrolladas sobre niveles métricos de conglomerados fracturados, constituyeron por tanto una defensa natural del enclave histórico.Palabras clave: enclave histórico, deslizamientos, estabilidad de taludes, conglomerados jurásicos.Abstract: The Rodiles hill, on the eastern shores of the Villaviciosa estuary, preserves evidences of historic occupation since the romans. The settlement has a defensive wall in the south and is bounded to the north by a cragged slope to the sea. This work investigates the relief and the structure of the rocks in the area aiming at finding an origin for the crags in the northeastern slope of the hill. Field observations and the analysis of the topography reveal the presence of several landslides that affect most of the northeastern hillside. The dip of the Jurassic rock sequence to the NE and the presence of a two meter-thick layer of shales, mechanically very plastic, below the La Ñora conglomerates Formation, mechanically very competent, favours the slip of the hillside. The scarps are aligned with the lateral termination of a Mesozoic normal fault, reactivated as a reverse fault during the formation of the Cantabrian Mountains. The head scarps at the back of the landslides, developed on fractured conglomerates, constituted a natural defence during the historic settlement.Keywords: historic settlement, slides, slope stability, Jurassic conglomerates.

scholarly journals GRAVIMETRIC GEOID MODELLING OVER PENINSULAR MALAYSIA USING TWO DIFFERENT GRIDDING APPROACHES FOR COMBINING FREE AIR ANOMALY

2019 ◽  
Vol XLII-4/W16 ◽  
pp. 515-522
Author(s):  
M. F. Pa’suya ◽  
A. H. M. Din ◽  
J. C. McCubbine ◽  
A. H. Omar ◽  
Z. M. Amin ◽  
...  
Keyword(s):  
Gravity Data ◽  
Reference Signal ◽  
Digital Terrain Model ◽  
Peninsular Malaysia ◽  
Airborne Gravity ◽  
Geopotential Model ◽  
Gravimetric Geoid ◽  
Geoid Model ◽  
Free Air ◽  
Free Air Anomaly

Abstract. We investigate the use of the KTH Method to compute gravimetric geoid models of Malaysian Peninsular and the effect of two differing strategies to combine and interpolate terrestrial, marine DTU17 free air gravity anomaly data at regular grid nodes. Gravimetric geoid models were produced for both free air anomaly grids using the GOCE-only geopotential model GGM GO_CONS_GCF_2_SPW_R4 as the long wavelength reference signal and high-resolution TanDEM-X global digital terrain model. The geoid models were analyzed to assess how the different gridding strategies impact the gravimetric geoid over Malaysian Peninsular by comparing themto 172 GNSS-levelling derived geoid undulations. The RMSE of the two sets of gravimetric geoid model / GNSS-levelling residuals differed by approx. 26.2 mm. When a 4-parameter fit is used, the difference between the RMSE of the residuals reduced to 8 mm. The geoid models shown here do not include the latest airborne gravity data used in the computation of the official gravimetric geoid for the Malaysian Peninsular, for this reason they are not as precise.

scholarly journals New Bouguer Gravity Maps of Venezuela: Representation and Analysis of Free-Air and Bouguer Anomalies with Emphasis on Spectral Analyses and Elastic Thickness

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Javier Sanchez-Rojas
Keyword(s):  
Gravity Data ◽  
Bouguer Anomaly ◽  
Geodetic Reference System ◽  
Bouguer Gravity ◽  
Free Air ◽  
Data Compilation ◽  
Regional Tectonic ◽  
Moho Depths ◽  
Free Air Anomaly ◽  
Gravity Map

A new gravity data compilation for Venezuela was processed and homogenized. Gravity was measured in reference to the International Gravity Standardization Net 1971, and the complete Bouguer anomaly was calculated by using the Geodetic Reference System 1980 and 2.67 Mg/m3. A regional gravity map was computed by removing wavelengths higher than 200 km from the Bouguer anomaly. After the anomaly separation, regional and residual Bouguer gravity fields were then critically discussed in term of the regional tectonic features. Results were compared with the previous geological and tectonic information obtained from former studies. Gravity and topography data in the spectral domain were used to examine the elastic thickness and depths of the structures of the causative measured anomaly. According to the power spectrum analysis results of the gravity data, the averaged Moho depths for the massif, plains, and mountainous areas in Venezuela are 42, 35, and 40 km, respectively. The averaged admittance function computed from the topography and Free-Air anomaly profiles across Mérida Andes showed a good fit for a regional compensation model with an effective elastic thickness of 15 km.

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.

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