An application of the second derivative as a tool in tectonic analysis in the Qattara Depression area, Egypt

1986 ◽  
Vol 123 (3) ◽  
pp. 307-313
Author(s):  
A. El-Hussaini ◽  
M. Youssef ◽  
H. Ibrahim
Keyword(s):  
Gravity Anomalies ◽  
Horizontal Displacement ◽  
Fault System ◽  
Second Derivative ◽  
Vertical Movements ◽  
Very Old ◽  
First Order ◽  
Basement Structures

AbstractThe second derivative of gravity anomalies of the Qattara area was analysed and statistically studied for determining the tectonic elements. Zones of zero second derivative were considered as the locations of possible faults. The analysis of a constructed tectonic map portrays the predominance of N45°W, N85°E and N45°E fault trends in addition to less pronounced N15°E and N–S faults. The NW–SE faults are very old and inherited from the basement structures. They acted as first order right-lateral wrench faults during the Alpine tectonism. Second and higher orders of faults, developed as a consequence of these movements, are represented by the N85°E and other less abundant trends. Vertical movements along the existing fault system, in addition to the horizontal displacement, is supported by the analysis of the pronounced anomalies of the second derivative map. The subsurface structural picture of the area is composed of uplifted and downfaulted adjoining blocks.

3D Visual Technology of Geo-Deformation Disasters Induced by Mining Subsidence Based on ArcGIS Engine

2012 ◽  
Vol 500 ◽  
pp. 428-436 ◽  
Author(s):  
Ke Ming Yang ◽  
Jun Ting Ma ◽  
Bo Pang ◽  
Yi Bin Wang ◽  
Ran Wang ◽  
...  
Keyword(s):  
Coal Mining ◽  
Surface Deformation ◽  
Ground Deformation ◽  
Ground Surface ◽  
Horizontal Displacement ◽  
Mining Subsidence ◽  
Underground Coal Mining ◽  
Vertical Movements ◽  
Probability Integral Method ◽  
Arcgis Engine

Mining subsidence often produces significant horizontal and vertical movements at the ground surface, the surface deformation induced by underground coal mining can be predicted by probability integral method, and the surface geo-deformation disasters can be visualized based on GIS components. A three dimensional (3D) visualizing system of surface geo-deformation information is designed and developed with ArcGIS Engine and C# in the study. According to the surface deformation-predicted data induced by underground coal mining in Guobei Coalmine of Huaibei mine field, the extents and degrees of ground deformation disasters are visualized in 3D views for surface vertical subsidence, slope, curvature, horizontal displacement and horizontal strain based on the GIS-developed application platform.

Pattern of recent vertical crustal movements in Maritime Canada

1976 ◽  
Vol 13 (5) ◽  
pp. 661-667 ◽  
Author(s):  
Petr Vaníček
Keyword(s):  
New Brunswick ◽  
Sea Level ◽  
Bay Of Fundy ◽  
Vertical Movements ◽  
Crustal Movements ◽  
First Order ◽  
Level Data ◽  
Velocity Surface ◽  
Maritime Canada ◽  
Vertical Crustal Movements

A surface depicting linear vertical movements in Maritime Canada was computed from sea-level data recorded by 8 tide guages and 308 mostly disjoint, relevelled segments of the first-order Canadian levelling network. Owing to the sparsity of the available data and their distribution, the velocity surface must be regarded as indicative of the crude features only. The indications are that there is a west-northwest trending belt of faster subsidence across the eastern end of the Bay of Fundy, and that there may be an area of uplift in northeastern New Brunswick. Although the faster subsidence around the eastern Bay of Fundy seems to be well established now, more data are needed to prove or dispel the existence of the indicated uplift.

Corner Reflector Network as a Geodetic Reference for Landslide Monitoring via InSAR Time Series: Case Study from Slovakia

2021 ◽  
Author(s):  
Richard Czikhardt ◽  
Juraj Papco ◽  
Peter Ondrejka ◽  
Peter Ondrus ◽  
Pavel Liscak
Keyword(s):  
Time Series ◽  
Horizontal Displacement ◽  
Terrestrial Reference Frame ◽  
Sar Interferometry ◽  
Global Navigation Satellite Systems ◽  
Reference Network ◽  
Landslide Monitoring ◽  
First Order ◽  
Order Estimation ◽  
Better Than

<p>SAR interferometry (InSAR) is inherently a relative geodetic technique requiring one temporal and one spatial reference to obtain the datum-free estimates on millimetre-level displacements within the network of radar scatterers. To correct the systematic errors, such as the varying atmospheric delay, and solve the phase ambiguities, it relies on the first-order estimation network of coherent point scatterers (PS).</p><p>For vegetated and sparsely urbanized areas, commonly affected by landslides in Slovakia, it is often difficult to construct a reliable first-order estimation network, as they lack the PS. Purposedly deploying corner reflectors (CR) at such areas strengthens the estimation network and, if these CR are collocated with a Global Navigation Satellite Systems (GNSS), they provide an absolute geodetic reference to a well-defined terrestrial reference frame (TRF), as well as independent quality control.</p><p>For landslides, line-of-sight (LOS) InSAR displacements can be difficult to interpret. Using double CR, i.e. two reflectors for ascending/descending geometries within a single instrument, enables the assumption-less decomposition of the observed cross-track LOS displacements into the vertical and the horizontal displacement components.</p><p>In this study, we perform InSAR analysis on the one-year of Sentinel-1 time series of five areas in Slovakia, affected by landslides. 24 double back-flipped trihedral CR were carefully deployed at these sites to form a reference network, guaranteeing reliable displacement information over the critical landslide zones. To confirm the measurement quality, we show that the temporal average Signal-to-Clutter Ratio (SCR) of the CR is better than 20 dB. The observed CR motions in vertical and east-west directions vary from several millimetres up to 3 centimetres, with average standard deviation better than 0.5 mm.<br>Repeated GNSS measurements of the CR confirm the displacement observed by the InSAR, improve the positioning precision of the nearby PS, and attain the transformation into the national TRF.</p>

Integrated Geophysical Interpretation of Kerio Valley Basin Stratigraphy, Kenya Rift

2016 ◽  
Author(s):  
Godfred Osukuku ◽  
Abiud Masinde ◽  
Bernard Adero ◽  
Edmond Wanjala ◽  
John Ego
Keyword(s):  
Gravity Data ◽  
Gravity Anomalies ◽  
Fault System ◽  
Magnetic Data ◽  
Data Sets ◽  
Seismic Profiles ◽  
The West ◽  
Seismic Reflection Data ◽  
Basement Rocks ◽  
Western Side

Abstract This research work attempts to map out the stratigraphic sequence of the Kerio Valley Basin using magnetic, gravity and seismic data sets. Regional gravity data consisting of isotactic, free-air and Bouguer anomaly grids were obtained from the International Gravity Bureau (BGI). Magnetic data sets were sourced from the Earth Magnetic Anomaly grid (EMAG2). The seismic reflection data was acquired in 1989 using a vibrating source shot into inline geophones. Gravity Isostacy data shows low gravity anomalies that depict a deeper basement. Magnetic tilt and seismic profiles show sediment thickness of 2.5-3.5 Km above the basement. The Kerio Valley Basin towards the western side is underlain by a deeper basement which are overlain by succession of sandstones/shales and volcanoes. At the very top are the mid Miocene phonolites (Uasin Gishu) underlain by mid Miocene sandstones/shales (Tambach Formation). There are high gravity anomalies in the western and southern parts of the basin with the sedimentation being constrained by two normal faults. The Kerio Valley Basin is bounded to the west by the North-South easterly dipping fault system. Gravity data was significantly of help in delineating the basement, scanning the lithosphere and the upper mantle according to the relative densities. The basement rocks as well as the upper cover of volcanoes have distinctively higher densities than the infilled sedimentary sections within the basin. From the seismic profiles, the frequency of the shaley rocks and compact sandstones increases with depths. The western side of the basin is characterized by the absence of reflections and relatively higher frequency content. The termination of reflectors and the westward dip of reflectors represent a fault (Elgeyo fault). The reflectors dip towards the west, marking the basin as an asymmetrical syncline, indicating that the extension was towards the east. The basin floor is characterized by a nearly vertical fault which runs parallel to the Elgeyo fault. The seismic reflectors show marked discontinuities which may be due to lava flows. The deepest reflector shows deep sedimentation in the basin and is in reasonable agreement with basement depths delineated from potential methods (gravity and magnetic). Basement rocks are deeper at the top of the uplift footwall of the Elgeyo Escarpment. The sediments are likely of a thickness of about 800 M which is an interbed of sandstones and shales above the basement.

First Order Stochastic Lagrange Model for Asymmetric Ocean Waves

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Georg Lindgren ◽  
Sofia Åberg
Keyword(s):  
Numerical Algorithms ◽  
Wave Model ◽  
Ocean Waves ◽  
Point Of View ◽  
Irregular Waves ◽  
Linear Wave ◽  
Ocean Engineering ◽  
Vertical Movements ◽  
First Order ◽  
Water Conditions

The Gaussian linear wave model, which has been successfully used in ocean engineering for more than half a century, is well understood, and there exist both exact theory and efficient numerical algorithms for calculation of the statistical distribution of wave characteristics. It is well suited for moderate seastates and deep water conditions. One drawback, however, is its lack of realism under extreme or shallow water conditions, in particular, its symmetry. It produces waves, which are stochastically symmetric, both in the vertical and in the horizontal direction. From that point of view, the Lagrangian wave model, which describes the horizontal and vertical movements of individual water particles, is more realistic. Its stochastic properties are much less known and have not been studied until quite recently. This paper presents a version of the first order stochastic Lagrange model that is able to generate irregular waves with both crest-trough and front-back asymmetries.

scholarly journals Geometry of the inverted Cretaceous Chañarcillo Basin based on 2-D gravity and field data. An approach to the structure of the western Central Andes of northern Chile

2015 ◽  
Vol 7 (3) ◽  
pp. 2311-2346
Author(s):  
F. Martínez ◽  
A. Maksymowicz ◽  
H. Ochoa ◽  
D. Díaz
Keyword(s):  
Normal Fault ◽  
Gravity Anomalies ◽  
Integrated Approach ◽  
Central Andes ◽  
Fault System ◽  
Northern Chile ◽  
Gravity Gradients ◽  
Structural Geometry ◽  
Geological Information ◽  
New Ideas

Abstract. This paper discusses an integrated approach that provides new ideas about the structural geometry of the NNE-striking, Cretaceous Chañarcillo Basin located along the eastern Coastal Cordillera in the western Central Andes of northern Chile (27–28° S). The results obtained from the integration of two transverse (E–W) gravity profiles with previous geological information, show that the architecture of this basin is defined by a large NNE–SSE-trending and east-vergent anticline ("Tierra Amarilla Anticlinorium"), which is related to the positive reactivation of a former Cretaceous normal fault (Elisa de Bordos Master Fault). Moreover, intercalations of high and low gravity anomalies and steep gravity gradients reveal a set of buried, west-tilted half-grabens associated with a synthetic normal fault pattern. These results, together with the uplift and folding style of the Cretaceous syn-rift recognized within the basin, suggest that their complete structural geometry could be explained by an inverted fault system linked to the shortening of pre-existing Cretaceous normal fault systems. Ages of the synorogenic deposits exposed unconformably over the frontal limb of the Tierra Amarilla Anticlinorium confirm a Late Cretaceous age for the Andean deformation and tectonic inversion of the basin.

Second Derivative Calculations

Geophysics ◽  
1954 ◽  
Vol 19 (2) ◽  
pp. 342-342
Author(s):  
Bruno F. J. Kunz ◽  
A. A. Rohoel-Gewinnungs
Keyword(s):  
Gravity Data ◽  
Gravity Anomalies ◽  
Test Area ◽  
The Other ◽  
Computation Method ◽  
Second Derivative ◽  
Methods Of Calculation

Leo J. Peter's and Thomas A. Elkins' remarks in reference to “Computation of the ‘Second Derivative’ from Gravity Data’ by O. Rosenbach (Geophysics, v. 18, p. 894-912. October 1953) and the author's reply are very interesting but they cannot satisfy the reader. From Figure “A”, one of the two methods of calculation looks better; from Figure “B” the other. Dr. Rosenbach, on p. 912, suggests that his critics may not have applied his computation method carefully enough and requests that they make available to him the observed gravity anomalies in the test area of Figure “Aȁ The same possibility might apply to the example in Figure “B” selected by the author. In this case too it would be desirable for the reader to be able to examine the observed gravity anomalies.

Computational Treatment of First Order Delay Differential Equations Using Hybrid Extended Second Derivative Block Backward Differentiation Formulae

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
C. Chibuisi ◽  
Bright Okore Osu ◽  
C. Olunkwa ◽  
S. A. Ihedioha ◽  
S. Amaraihu
Keyword(s):  
Differential Equations ◽  
Delay Differential Equations ◽  
Second Derivative ◽  
Delay Term ◽  
First Order ◽  
Block Form ◽  
Collocation Approach ◽  
Backward Differentiation Formulae ◽  
Delay Differential ◽  
Step Number

This paper considers the computational solution of first order delay differential equations (DDEs) using hybrid extended second derivative backward differentiation formulae method in block form without the implementation of interpolation techniques in estimating the delay term. By matrix inversion approach, the discrete schemes were obtained through the linear multistep collocation approach from the continuous form of each step number which after implementation strongly revealed the convergence and region of absolute stability of the proposed method. Computational results are presented and compared to the exact solutions and other existing method to demonstrate its efficiency and accuracy.

Sm–Nd isotopic geochemistry of Precambrian to Paleozoic granitoid suites and the deep-crustal structure of the southeast margin of the Newfoundland Appalachians

1995 ◽  
Vol 32 (2) ◽  
pp. 224-245 ◽  
Author(s):  
Andrew Kerr ◽  
George A. Jenner ◽  
Brian J. Fryer
Keyword(s):  
Fault System ◽  
Mobile Belt ◽  
Simple Extension ◽  
Precambrian Basement ◽  
Zone Boundary ◽  
First Order ◽  
Metasedimentary Rocks ◽  
Late Precambrian ◽  
Deep Crustal Structure ◽  
Appalachian Orogen

In the Eastern Central Mobile Belt of the Newfoundland Appalachians, late Precambrian basement inliers have εNd from −3 to +2, but Cambro-Ordovician metasedimentary rocks have initial εNd below −7. This region is inferred to have an "inverted" crustal residence structure, which influenced subsequent Appalachian-cycle magmatism. Ordovician and Silurian granitoid suites have εNd of −8 to −2, bracketing both basement and cover, but peraluminous, "S-type" granites have the lowest εNd. Devonian granites have initial εNd values from −5 to +1, and low εNd is associated with peraluminous character. These Paleozoic granites show geographic trends, with lowest εNd values in areas where metasedimentary rocks are abundant. They are suggested to contain anatectic material from both Precambrian basement and metasedimentary cover, but some "I-type" suites probably also include a mantle-derived component. In the adjacent Avalon Zone, Precambrian plutonic suites mostly have εNd from +1 to +6, but there are negative εNd values (−8 to −4) in the westernmost Avalon Zone. Devonian plutonic suites mostly have εNd from +2 to +5. Thus, the Precambrian crust of the Avalon Zone is largely "juvenile," except at its westernmost edge. Contrasts across the Eastern Central Mobile Belt–Avalon Zone boundary, defined by the Dover–Hermitage Bay fault system, indicate a major, crustal-scale structure, and suggest an isotopically distinct "central block" beneath the central Appalachian Orogen, rather than a simple extension of "Avalonian" crust. Similar geographic–isotopic patterns have been reported in Nova Scotia and New Brunswick, suggesting that this pattern represents a first-order deep-crustal subdivision of the northern Appalachian Orogen.

Revisiting Toba Caldera: an insight from regional magnetotelluric data

2020 ◽  
Author(s):  
Lukman Sutrisno ◽  
Fred Beekman ◽  
Yunus Daud ◽  
Jan Diederik Van Wees
Keyword(s):  
Fault System ◽  
High Resistivity ◽  
Magnetotelluric Data ◽  
Recording Time ◽  
Magma Plumbing System ◽  
Basement Structures ◽  
Clay Cap ◽  
Surface Geology ◽  
Toba Caldera ◽  
Sumatran Fault

<p>Regional magnetotelluric (MT) survey had been conducted to image resistivity structures beneath Toba Caldera, Indonesia. A crustal-scale 2D inversion model is generated from ten MT stations with extended recording time, deployed along NE-SW regional line to cross perpendicularly both the Caldera and the nearby regional strike-slip fault system, the Sumatran Fault. High resistivity background is likely related to Palaeozoic rocks which is basement of the Tertiary sediments and the Quaternary volcanics. The most noticeable conductive anomaly is located between 10-20 km deep, interpreted as the main magma reservoir beneath the region. An intermediate, less than 10 km-deep, less conductive anomaly beneath the Caldera is interpreted as shallow magma chamber affected by the last major eruption. Shallow, less than 2 km-deep conductive layers are associated either with hydrothermal clay cap beneath the Caldera, or sedimentary formations of the nearby basins. Other conductive anomaly is spatially associated with the Sumatran Fault which located 15 km away from the Caldera. Parameter plots of some stations are consistent with the orientation of basement structures, while the others may be affected by more complex caldera structures. A conceptual model of magma plumbing system beneath the Caldera is then interpreted from the combination of regional resistivity structures, surface geology, and available seismic tomography.</p>

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