SASSY21: A 3-D seismic structural model of the lithosphere and underlying mantle beneath Southeast Asia from multi-scale adjoint waveform tomography

Abstract. This study was carried out in the Lom series in Cameroun, at the border with Central African Republic located between the latitudes 5°30′–6° N and the longitudes 13°30′–14°45′ E. A multi-scale analysis of aeromagnetic data combining tilt derivative, Euler deconvolution, upward continuation and the 2.75D modelling was used. The following conclusion were drawn: 1 – Several major families of faults were mapped. Their orientations are ENE-WSW, E-W, NW-SE, N-S with a NE-SW prevalence. The latter are predominantly sub-vertical with NW and SW dips and appear to be prospective for the future mining investigation. 2 – The evidence of compression, folding and shearing axis, was concluded from superposition of null contours of the tilt-derivative and Euler deconvolution. The evidence of the local tectonics principally due to several deformation episodes (D1, D2 and D4) associated with NE-SW, E-W, and NW-SE events respectively. 3 – Depths of interpreted faults ranges from 1000 to 3400 m. 4 – Several linear structures correlating with known mylonitic veins were identified. These are associated with the Lom faults and represent the contacts between the Lom series and the granito-gneissic rocks; we concluded the intense foldings caused by senestral and dextral NE-SW and NW-SE stumps; 5 – We propose a structural model of the top of the crust (schists, gneisses, granites) that delineates principal intrusions (porphyroid granite, garnet gneiss, syenites, micaschists, Graphite and Garnet gneiss) responsible for the observed anomalies. The 2.75D modelling revealed; many faults with a depth greater than 1200 m and confirmed the observations from RTE-TMI, Tilt derivative and Euler deconvolution; 6 – We developed lithologic profile of Betare Oya basin.

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Multi-scale model updating of a timber footbridge using experimental vibration data

Engineering Computations ◽

10.1108/ec-09-2015-0284 ◽

2017 ◽

Vol 34 (3) ◽

pp. 754-780 ◽

Cited By ~ 1

Author(s):

Rafael Castro-Triguero ◽

Enrique Garcia-Macias ◽

Erick Saavedra Flores ◽

M.I. Friswell ◽

Rafael Gallego

Keyword(s):

Structural Model ◽

Model Updating ◽

Ambient Vibration ◽

Scale Model ◽

Structural Behavior ◽

Modal Parameters ◽

Content Type ◽

Multi Scale ◽

Ambient Vibration Tests ◽

Vibration Tests

Purpose The purpose of this paper is to capture the actual structural behavior of the longest timber footbridge in Spain by means of a multi-scale model updating approach in conjunction with ambient vibration tests. Design/methodology/approach In a first stage, a numerical pre-test analysis of the full bridge is performed, using standard beam-type finite elements with isotropic material properties. This approach offers a first structural model in which optimal sensor placement (OSP) methodologies are applied to improve the system identification process. In particular, the effective independence (EFI) method is used to determine the optimal locations of a set of sensors. Ambient vibration tests are conducted to determine experimentally the modal characteristics of the structure. The identified modal parameters are compared with those values obtained from this preliminary model. To improve the accuracy of the numerical predictions, the material response is modeled by means of a homogenization-based multi-scale computational approach. In a second stage, the structure is modeled by means of three-dimensional solid elements with the above material definition, capturing realistically the full orthotropic mechanical properties of wood. A genetic algorithm (GA) technique is adopted to calibrate the micromechanical parameters which are either not well-known or susceptible to considerable variations when measured experimentally. Findings An overall good agreement is found between the results of the updated numerical simulations and the corresponding experimental measurements. The longitudinal and transverse Young's moduli, sliding and rolling shear moduli, density and natural frequencies are computed by the present approach. The obtained results reveal the potential predictive capabilities of the present GA/multi-scale/experimental approach to capture accurately the actual behavior of complex materials and structures. Originality/value The uniqueness and importance of this structure leads to an intensive study of its structural behavior. Ambient vibration tests are carried out under environmental excitation. Extraction of modal parameters is obtained from output-only experimental data. The EFI methodology is applied for the OSP on a large-scale structure. Information coming from several length scales, from sub-micrometer dimensions to macroscopic scales, is included in the material definition. The strong differences found between the stiffness along the longitudinal and transverse directions of wood lumbers are incorporated in the structural model. A multi-scale model updating approach is carried out by means of a GA technique to calibrate the micromechanical parameters which are either not well-known or susceptible to considerable variations when measured experimentally.

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Image Stereo Matching Based on Multi-Scale Plane Set

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.709.527 ◽

2013 ◽

Vol 709 ◽

pp. 527-533 ◽

Cited By ~ 1

Author(s):

Xin Hui Jiang ◽

Shao Jun Yu ◽

Xing Jiang

Keyword(s):

Dynamic Programming ◽

Stereo Matching ◽

Structural Model ◽

Dynamic Programming Algorithm ◽

Programming Method ◽

Programming Algorithm ◽

Dynamic Programming Method ◽

Disparity Map ◽

Matching Method ◽

Multi Scale

The disparity map of dynamic programming method is poor. To overcome it, a stereo matching method based on multi-scale plane set is proposed in this paper. This method converts the structural model into the plane set. Define the key plane. Then the key planes are in a high-scale. The other planes are in the low scale. Stereo matching the multi-scale plane set using dynamic programming method. The experimental results show that: this method can solve the dynamic programming algorithm`s problem that disparity map has low matching accuracy and a lot of stripes error.

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Fast interpolation method for surfaces with faults by multi-scale second-derivative optimization

Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles ◽

10.2516/ogst/2020057 ◽

2020 ◽

Vol 75 ◽

pp. 62

Author(s):

Michel Léger ◽

Vincent Clochard

Keyword(s):

Seismic Data ◽

Single Unit ◽

Input Data ◽

Structural Model ◽

Interpolation Method ◽

Second Derivative ◽

Multi Scale ◽

Surface Interpolation ◽

First Derivative ◽

Fault Network

We present a smooth surface interpolation method enabling to take discontinuities (e.g. faults) into account that can be applied to any dataset defined on a regular mesh. We use a second-derivative multi-scale minimization based on a conjugate gradient method. Our multi-scale approach allows the algorithm to process millions of points in a few seconds on a single-unit workstation. The interpolated surface is continuous, as well as its first derivative, except on some lines that have been specified as discontinuities. Application in geosciences are numerous, for instance when a structural model is to be built from points picked on seismic data. The resulting dip of interpolation extends the dip of the input data. The algorithm also works if faults are given by broken lines. We present results from a synthetic and real examples taking into account fault network.

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Multi-scale analysis and modelling of aeromagnetic data over the Bétaré-Oya area in eastern Cameroon, for structural evidence investigations

Solid Earth ◽

10.5194/se-12-785-2021 ◽

2021 ◽

Vol 12 (4) ◽

pp. 785-800

Author(s):

Christian Emile Nyaban ◽

Théophile Ndougsa-Mbarga ◽

Marcelin Bikoro-Bi-Alou ◽

Stella Amina Manekeng Tadjouteu ◽

Stephane Patrick Assembe

Keyword(s):

Central African Republic ◽

Structural Model ◽

Scale Analysis ◽

Aeromagnetic Data ◽

Euler Deconvolution ◽

Multi Scale ◽

Tilt Derivative ◽

Local Tectonics ◽

Multi Scale Analysis ◽

Eastern Cameroon

Abstract. This study was carried out in the Lom series in Cameroon, at the border with Central African Republic, located between the latitudes 5∘30′–6∘ N and the longitudes 13∘30′–14∘45′ E. A multi-scale analysis of aeromagnetic data combining tilt derivative, Euler deconvolution, upward continuation, and 2.75D modelling was used. The following conclusions were drawn. (1) Several major families of faults were mapped. Their orientations are ENE–WSW, E–W, NW–SE, and N–S with a NE–SW prevalence. The latter are predominantly sub-vertical with NW and SW dips and appear to be prospective for future mining investigations. (2) The evidence of compression, folding, and shearing axis was concluded from superposition of null contours of the tilt derivative and Euler deconvolution. The principal evidence of the local tectonics was due to several deformation episodes (D1, D2, and D4) associated with NE–SW, E–W, and NW–SE events, respectively. (3) Depths of interpreted faults range from 1000 to 3400 m. (4) Several linear structures correlating with known mylonitic veins were identified. These are associated with the Lom faults and represent the contacts between the Lom series and the granito-gneissic rocks; we concluded the intense folding was caused by senestral and dextral NE–SW and NW–SE stumps. (5) We propose a structural model of the top of the crust (schists, gneisses, granites) that delineates principal intrusions (porphyroid granite, garnet gneiss, syenites, micaschists, graphite, and garnet gneiss) responsible for the observed anomalies. The 2.75D modelling revealed many faults with a depth greater than 1200 m and confirmed the observations from reduced-to-Equator total magnetic intensity (RTE-TMI), tilt derivative, and Euler deconvolution. (6) We developed a lithologic profile of the Bétaré-Oya basin.

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Towards 3D Multiscale Adjoint Waveform Tomography of the Lithosphere and Underlying Mantle beneath Southeast Asia

10.5194/egusphere-egu21-1586 ◽

2021 ◽

Author(s):

Deborah Wehner ◽

Nienke Blom ◽

Nicholas Rawlinson ◽

Meghan Miller ◽

Sri Widiyantoro ◽

...

Keyword(s):

Southeast Asia ◽

Velocity Structure ◽

Signal To Noise Ratio ◽

Data Availability ◽

Velocity Anomaly ◽

Seismic Waveform ◽

Path Coverage ◽

Gradient Based ◽

Waveform Tomography ◽

Window Selection

Southeast Asia is one of the most complex tectonic regions on Earth. This is mainly a result of its location within the triple junction of the Australian, Eurasian and Philippine Sea plates which has created a complicated configuration of active plate tectonic boundaries. Adjoint waveform tomography is especially suitable for imaging such complex regions. By simulating the 3D wavefield, it is possible to directly compare observed and simulated seismograms, thereby taking into account both body and surface waves. The method can account for the effects of anisotropy, anelasticity, wavefront healing, interference and (de)focusing that can hamper other seismological methods.To date, sparse instrument coverage in the region has contributed to a heterogeneous path coverage. In this project, we make use of publicly available data as well as our recently deployed networks of broadband seismometers on Borneo and Sulawesi. This, in addition to access to national permanent networks, provides data from over 300 stations which promises a significant improvement in data coverage around the Banda Arc, Borneo and Sulawesi. We employ a geographical weighting scheme to minimise the effect of dense regional arrays and compile a catalogue of 118&#160;well-constrained earthquakes, optimising for coverage, signal-to-noise ratio and data availability. An optimised window selection algorithm allows us to balance amplitude differences and include as much signal as possible while avoiding noisy data.Here, we present a seismic waveform tomography for upper mantle structure in Southeast Asia, imaging radially anisotropic S velocity, P velocity and density. We use a gradient-based optimisation scheme (L-BFGS) and adjoint methods to obtain sensitivity kernels as the corresponding gradients.&#160;In the first part of the inversion, periods down to 50 s are used to update a 1D initial model, adapting a multi-scale approach in which long periods are inverted for first to avoid cycle skipping.&#160;In our long-period results, we observe a strong&#160;regional low S-velocity structure with an underlying high-velocity anomaly. The&#160;results&#160;are&#160;consistent with the global&#160;S40RTS model.&#160;

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Towards 3D multiscale adjoint waveform tomography of the crust and upper mantle beneath Southeast Asia

10.5194/egusphere-egu2020-694 ◽

2020 ◽

Author(s):

Deborah Wehner ◽

Nienke Blom ◽

Nick Rawlinson

Keyword(s):

Southeast Asia ◽

Upper Mantle ◽

Signal To Noise Ratio ◽

Data Availability ◽

Tectonic Activity ◽

Initial Model ◽

Crust And Upper Mantle ◽

Banda Arc ◽

Waveform Tomography ◽

Krakatoa Eruption

Southeast Asia is one of the most complex tectonic regions on Earth. This is mainly a result of its location within the triple junction of the Australian, Eurasian and Philippine Sea plates which has created a complicated configuration of active plate tectonic boundaries. High plate velocities have generated thousands of kilometers of subducted material and ongoing subduction along the Sunda Arc represents a significant natural hazard (such as the 2004 Sumatra-Andaman earthquake, 2012 Indian Ocean earthquakes and 2018 Anak Krakatoa eruption). However, recent tectonic activity around Borneo may be related to postsubduction processes which could be the key to understanding how the tectonic subduction cycle terminates. Further east, the region is dominated by several minor tectonic plates and the spectacular 180-degree curvature of the Banda Arc. Our work aims to further improve the understanding of this area by providing detailed images of the upper mantle.Adjoint waveform tomography is especially suitable for imaging such complex regions. By simulating the 3D wavefield, it is possible to directly compare observed and simulated seismograms, thereby taking into account both body and surface waves. The method can account for the effects of anisotropy, anelasticity, wavefront healing, interference and (de)focusing that can hamper other seismological methods, and is thus especially suitable for strongly heterogenous areas such as Southeast Asia.To date, sparse instrument coverage in the region has contributed to a heterogeneous path coverage. In this project, we make use of publicly available data as well as our recently deployed networks of broadband seismometers on Borneo and Sulawesi. This, in addition to access to national permanent networks promises a significant improvement in data coverage around the Banda Arc, Borneo and Sulawesi, thereby providing new opportunities to untangle the region&#8217;s complexity.We compiled a catalogue of well-constrained earthquakes, optimising for coverage, signal-to-noise ratio and data availability across a wide frequency band, and compared our observed data to synthetics generated from an initial model. In the first part of the inversion, we use long periods of 100 - 150 s to update our initial model using a gradient-based optimisation scheme. We use adjoint methods to obtain sensitivity kernels as the corresponding gradients and initial results will be documented in this presentation. In subsequent iterations, we permit increasingly shorter periods in order to progressively recover finer scales structure and avoid cycle skipping issues.

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Assessing rice productivity and adaptation strategies for Southeast Asia under climate change through multi-scale crop modeling

Agricultural Systems ◽

10.1016/j.agsy.2015.12.001 ◽

2016 ◽

Vol 143 ◽

pp. 14-21 ◽

Cited By ~ 30

Author(s):

Jong Ahn Chun ◽

Sanai Li ◽

Qingguo Wang ◽

Woo-Seop Lee ◽

Eun-Jeong Lee ◽

...

Keyword(s):

Climate Change ◽

Southeast Asia ◽

Adaptation Strategies ◽

Crop Modeling ◽

Rice Productivity ◽

Multi Scale

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Modeling Hsp70/Hsp40 interaction by multi-scale molecular simulations and co-evolutionary sequence analysis

10.1101/067421 ◽

2016 ◽

Author(s):

Duccio Malinverni ◽

Alfredo Jost Lopez ◽

Paolo De Los Rios ◽

Gerhard Hummer ◽

Alessandro Barducci

Keyword(s):

Sequence Analysis ◽

Structural Model ◽

Molecular Simulations ◽

Evolutionary Sequence ◽

Multi Scale ◽

Atomistic Models ◽

Structural Details ◽

Shock Proteins ◽

Interaction Surface ◽

Shed Light

AbstractThe interaction between the Heat Shock Proteins 70 and 40 is at the core of the ATPase regulation of the chaperone machinery that maintains protein homeostasis. However, the structural details of this fundamental interaction are still elusive and contrasting models have been proposed for the transient Hsp70/Hsp40 complexes. Here we combine molecular simulations based on both coarsegrained and atomistic models with co-evolutionary sequence analysis to shed light on this problem by focusing on the bacterial DnaK/DnaJ system. The integration of these complementary approaches resulted into a novel structural model that rationalizes previous experimental observations. We identify an evolutionary-conserved interaction surface formed by helix II of the DnaJ J-domain and a groove on lobe IIA of the DnaK nucleotide binding domain, involving the inter-domain linker.

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