3DMRT: A Computer Package for 3D Model‐Based Seismic Wave Propagation

2019 ◽  
Author(s):  
Pingan Peng ◽  
Liguan Wang
Keyword(s):  
High Performance ◽  
3D Model ◽  
Heterogeneous Media ◽  
Velocity Model ◽  
Seismic Wave Propagation ◽  
Major Interest ◽  
Command Line Tool ◽  
Global Seismology ◽  
Geologic Model ◽  
Free Open Source

ABSTRACT The prediction of accurate source‐to‐receiver travel times and wave paths through heterogeneous media is of major interest in global seismology and microseismic communities. Many algorithms have been proposed to address this problem, among which eikonal solvers have the best accuracy but lack computational efficiency. To facilitate the use of eikonal solvers with a high performance and visualization ability, this article presents a free, open‐source, graphical package named 3DMRT. 3DMRT propagates wavefronts through a 3D heterogeneous medium. Starting with a geologic model, the package first constructs a gridded velocity model. The application implements nine eikonal solvers and provides one‐point and multipoint raytracing functionality. In addition, 3DMRT is complemented with an additional command line tool that allows integration into other programs for further applications.

scholarly journals A simple P-wave polarization analysis: its application to earthquake location

1994 ◽  
Vol 37 (5) ◽  
Author(s):  
B. Alessandrini ◽  
M. Cattaneo ◽  
M. Demartin ◽  
M. Gasperini ◽  
V. Lanza
Keyword(s):  
Ground Motion ◽  
Seismic Wave ◽  
Heterogeneous Media ◽  
Seismic Wave Propagation ◽  
Least Square ◽  
P Wave ◽  
Motion Direction ◽  
Arrival Times ◽  
Hypocentral Location ◽  
Ray Path

We present a method for hypocentral location which takes into account all three components of ground motion and not only the vertical one, as it is usually done by standard least-square techniques applied to arrival times. Assuming that P-wave particle motion direction corresponds to the propagation direction of the seismic wave, we carried out a simple statistical analysis of ground motion amplitudes, carefully using three-component records. We obtained the azimuth and the emersion angle of the seismic ray, which, added to Pg and Sg arrival times, allowed us to find reliable hypocentral coordinates of some local events by means of a ray-tracing technique. We compared our locations to those obtained using a least-square technique: our polarization method's dependence on the accuracy of the model used (on the contrary, the least-square technique proved to be quite stable with respect to changes in the model's velocity parameters) led us to conclude that polarization data provide coherent information on the true ray-path and can be successfully used for both location procedures and seismic wave propagation studizs in strongly heterogeneous media.

scholarly journals Geological modeling of a hydrocarbon reservoir in the northeastern Llanos Orientales basin of Colombia

2021 ◽  
Vol 48 (2) ◽  
Author(s):  
Laura Juliana Rojas Cárdenas ◽  
Indira Molina
Keyword(s):  
3D Model ◽  
Water Saturation ◽  
Petrophysical Properties ◽  
Hydrocarbon Reservoir ◽  
A Value ◽  
Structural Surface ◽  
Geologic Model ◽  
Oil Water ◽  
Original Oil In Place ◽  
Operating Company

An hydrocarbon reservoir was characterized via a detailed geologic model, which allowed estimation of the original oil in place. The study characterizes a hydrocarbon reservoir of two fields of unit C7 of the Carbonera Formation within the Llanos Orientales basin of Colombia. This was done using well logs, the structural surface of the regional datum of the area, segments of the Yuca fault and a local fault of the reservoir, the  permeability equation, and J functions of the reservoir provided by the operating company. With this  information, a two-fault model and a grid with 3D cells was created. Each cell was assigned with a value of facies and petrophysical properties: porosity, permeability, and water saturation, to obtain a 3D model of  facies and petrophysical properties. Subsequently, we used the constructed models and oil-water contacts to  calculate the original oil in place for each field. Field 1 has a volume of six million barrels of oil and field 2 has  9 million barrels. 

Source Parameter Sensitivity of Earthquake Simulations assisted by Machine Learning 

2021 ◽  
Author(s):  
Marisol Monterrubio-Velasco ◽  
J. Carlos Carrasco-Jimenez ◽  
Otilio Rojas ◽  
Juan E. Rodriguez ◽  
David Modesto ◽  
...  
Keyword(s):  
Machine Learning ◽  
High Performance ◽  
Moment Tensor ◽  
Source Parameters ◽  
Velocity Model ◽  
Source Parameter ◽  
Earthquake Simulation ◽  
Centroid Moment Tensor ◽  
Ground Shaking ◽  
Earthquake Simulations

<p>After large magnitude earthquakes have been recorded, a crucial task for hazard assessment is to quickly estimate Ground Shaking (GS) intensities at the affected region. Urgent physics-based earthquake simulations using High-Performance Computing (HPC) facilities may allow fast GS intensity analyses but are very sensitive to source parameter values. When using fast estimates of source parameters such as magnitude, location, fault dimensions, and/or Centroid Moment Tensor (CMT), simulations are prone to errors in their computed GS. Although the approaches to estimate earthquake location and magnitude are consolidated, depth location estimates are largely uncertain. Moreover, automatic CMT solutions are not always provided by seismological agencies, or such solutions are available at later times after waveform inversions allow the determination of moment tensor components. The uncertainty on these parameters, especially a few minutes after the earthquake has been registered, strongly affects GS maps resulting from simulations.</p><p>In this work, we present a workflow prototype to produce an uncertainty quantification method as a function of the source parameters. The core of this workflow is based on Machine Learning (ML) techniques. As a study case, we consider a domain of 110x80 km centered in 63.9ºN-20.6ºW in Southern Iceland, where the 17 best-mapped faults have hosted the historical events of the largest magnitude. We generate synthetic GS intensity maps using the AWP-ODC finite-difference code for earthquake simulation and a one-dimensional velocity model, with 40 recording surface stations. By varying a few source parameters (e.g. event magnitude, CMT, and hypocenter location), we finally model tens of thousands of hypothetical earthquakes. Our ML analog will then be able to relate GS intensity maps to source parameters, thus simplifying sensitivity studies.</p><p>Additionally, the results of this workflow prototype will allow us to obtain ML-based intensity maps a few seconds after an earthquake occurs exploiting the predictive power of ML techniques. We will evaluate the accuracy of these maps as standalone complements to GMPEs and simulations.</p>

scholarly journals Hepatocyte-based flow analytical bioreactor for online xenobiotics metabolism bioprediction

2017 ◽  
Vol 4 ◽  
pp. 184954351770289
Author(s):  
M Helvenstein ◽  
S Hambÿe ◽  
B Blankert
Keyword(s):  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
High Performance ◽  
Screening Tools ◽  
Oxide Nanoparticles ◽  
New Approach ◽  
Drug Candidates ◽  
Magnetically Trapped ◽  
Major Interest

The research for new in vitro screening tools for predictive metabolic profiling of drug candidates is of major interest in the pharmaceutical field. The main motivation is to avoid late rejection in drug development and to deliver safer drugs to the market. Thanks to the superparamagnetic properties of iron oxide nanoparticles, a flow bioreactor has been developed which is able to perform xenobiotic metabolism studies. The selected cell line (HepaRG) maintained its metabolic competencies once iron oxide nanoparticles were internalized. Based on magnetically trapped cells in a homemade immobilization chamber, through which a flow of circulating phase was injected to transport nutrients and/or the studied xenobiotic, off-line and online (when coupled to a high-performance liquid chromatography chain) metabolic assays were developed using diclofenac as a reference compound. The diclofenac demonstrated a similar metabolization profile chromatogram, both with the newly developed setup and with the control situation. Highly versatile, this pioneering and innovative instrumental design paves the way for a new approach in predictive metabolism studies.

Migration moveout analysis and depth focusing

Geophysics ◽  
1993 ◽  
Vol 58 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Claude F. Lafond ◽  
Alan R. Levander
Keyword(s):  
Heterogeneous Media ◽  
A Priori ◽  
Complex Structure ◽  
Tomographic Reconstruction ◽  
Synthetic Data ◽  
Real Data ◽  
Velocity Model ◽  
Velocity Analysis ◽  
Data Set ◽  
Velocity Models

Prestack depth migration still suffers from the problems associated with building appropriate velocity models. The two main after‐migration, before‐stack velocity analysis techniques currently used, depth focusing and residual moveout correction, have found good use in many applications but have also shown their limitations in the case of very complex structures. To address this issue, we have extended the residual moveout analysis technique to the general case of heterogeneous velocity fields and steep dips, while keeping the algorithm robust enough to be of practical use on real data. Our method is not based on analytic expressions for the moveouts and requires no a priori knowledge of the model, but instead uses geometrical ray tracing in heterogeneous media, layer‐stripping migration, and local wavefront analysis to compute residual velocity corrections. These corrections are back projected into the velocity model along raypaths in a way that is similar to tomographic reconstruction. While this approach is more general than existing migration velocity analysis implementations, it is also much more computer intensive and is best used locally around a particularly complex structure. We demonstrate the technique using synthetic data from a model with strong velocity gradients and then apply it to a marine data set to improve the positioning of a major fault.

Anisotropic full-waveform inversion with tilt-angle recovery

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. R135-R151 ◽  
Author(s):  
Herurisa Rusmanugroho ◽  
Ryan Modrak ◽  
Jeroen Tromp
Keyword(s):  
Tilt Angle ◽  
Transverse Isotropy ◽  
A Priori ◽  
Waveform Inversion ◽  
Transversely Isotropic ◽  
Seismic Wave Propagation ◽  
Full Waveform Inversion ◽  
Full Waveform ◽  
Anisotropic Strength ◽  
Global Seismology

By allowing spatial variations in the direction of the anisotropic fast axis, tilted transverse isotropy (TTI) helps to image complex or steeply dipping structures. Without a priori geologic constraints, however, recovery of all the anisotropic parameters can be nontrivial and nonunique. We adopt two methods for TTI inversion with tilt-angle recovery: one based on the familiar Voigt parameters, and another based on the so-called Chen and Tromp parameters known from regional and global seismology. These parameterizations arise naturally in seismic wave propagation and facilitate straightforward recovery of the tilt angle and anisotropic strength. In numerical experiments with vertical transversely isotropic starting models and TTI target models, we find that the Voigt as well as the Chen and Tromp parameters allow quick and robust recovery of steeply dipping anticlinal structures.

scholarly journals ER3D: a structural and geophysical 3D model of central Emilia-Romagna (Northern Italy) for numerical simulation of earthquake ground motion

2019 ◽  
Author(s):  
Peter Klin ◽  
Giovanna Laurenzano ◽  
M. Adelaide Romano ◽  
Enrico Priolo ◽  
Luca Martelli
Keyword(s):  
Numerical Simulations ◽  
Ground Motion ◽  
High Performance ◽  
3D Model ◽  
Northern Italy ◽  
Peak Ground Velocity ◽  
Earthquake Ground Motion ◽  
Po River ◽  
Epicentral Area ◽  
Local Seismic Response

Abstract. During the 2012 seismic sequence of Emilia region (Northern Italy), the earthquake ground motion in the epicentral area featured longer duration and higher velocity than those estimated by empirical-based prediction equations typically adopted in Italy. In order to explain these anomalies, we (1) build up a structural and geophysical 3D digital model of the crustal sector involved in the sequence, (2) reproduce the earthquake ground motion at some seismological stations through physics-based numerical simulations and (3) compare the observed recordings with the simulated ones. In this way we investigate how the earthquake ground motion in the epicentral area is influenced by local stratigraphy and geological structure buried under the Po Plain alluvium. Our study area covers approximately 5000 km2 and extends from the Po river right bank to the Northern Apennines morphological margin in N-S direction, and between the two chief towns of Reggio Emilia and Ferrara in W-E direction, involving a crustal volume with 20 km of thickness. We set up the 3D model by using already published geological and geophysical data, with a detail corresponding to a map at scale 1:250 000. The model depicts the stratigraphic and tectonic relationships of the main geological formations, the known faults and the spatial pattern of the seismic properties. Being a digital vector structure, the 3D model can be easily modified or refined locally for future improvements or applications. We exploited high performance computing to perform numerical simulations of the seismic wave propagation in the frequency range up to 2 Hz. In order to get rid of the finite source effects and validate the model response, we choose to reproduce the ground motion related to two moderate-size aftershocks of the 2012 Emilia sequence that were recorded by a large number of stations. The obtained solutions compare very well to the recordings available at about 30 stations, in terms of peak ground velocity and signal duration. Snapshots of the simulated wavefield allow us to explain the exceptional length of the observed ground motion as due to surface waves overtones that are excited in the alluvial basin by the buried ridge of the Mirandola anticline. Physics-based simulations using realistic 3D geo-models show eventually to be effective for assessing the local seismic response and the seismic hazard in geologically complex areas.

scholarly journals Structural origin of the high-performance light-emitting InGaN/AlGaN quantum disks

Nanoscale ◽  
2019 ◽  
Vol 11 (18) ◽  
pp. 8994-8999 ◽  
Author(s):  
Shaobo Cheng ◽  
Brian Langelier ◽  
Yong-Ho Ra ◽  
Roksana Tonny Rashid ◽  
Zetian Mi ◽  
...  
Keyword(s):  
High Performance ◽  
3D Model ◽  
Light Emitting ◽  
Quantum Disks

3D model showing the boomerang shape of the InGaN/AlGaN quantum disks.

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