Hybrid multiplicative time-reversal imaging reveals the evolution of microseismic events: Theory and field-data tests

Geophysics ◽  
2019 ◽  
Vol 84 (3) ◽  
pp. KS71-KS83 ◽  
Author(s):  
Tieyuan Zhu ◽  
Junzhe Sun ◽  
Davide Gei ◽  
José M. Carcione ◽  
Philippe Cance ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Reversal ◽  
Field Data ◽  
Source Area ◽  
Spatiotemporal Distribution ◽  
Source Image ◽  
Imaging Method ◽  
Source Imaging ◽  
Receiver Array ◽  
Microseismic Events

The generation of microseismic events is often associated with induced fractures/faults during the extraction/injection of fluids. A full characterization of the spatiotemporal distribution of microseismic events provides constraints on fluid migration paths in the formations. We have developed a high-resolution source imaging method — a hybrid multiplicative time-reversal imaging (HyM-TRI) algorithm, for automatically tracking the spatiotemporal distribution of microseismic events. HyM-TRI back propagates the data traces from groups of receivers (in space and time) as receiver wavefields, multiplies receiver wavefields between all groups, and applies a causal integration over time to obtain a source evolution image. Using synthetic and field-data examples, we revealed the capability of the HyM-TRI technique to image the spatiotemporal sequence of asynchronous microseismic events, which poses a challenge to standard TRI methods. Moreover, the HyM-TRI technique is robust enough to produce a high-resolution image of the source in the presence of noise. The aperture of the 2D receiver array (azimuth coverage in 3D) with respect to the microseismic source area plays an important role on the horizontal and vertical resolution of the source image. The HyM-TRI results of the field data with 3D azimuthal coverage further verify our argument by producing a superior resolution of the source than TRI.

High-resolution source imaging based on time-reversal wave propagation simulations using assimilated dense seismic records

2020 ◽  
Author(s):  
Takashi Furumura ◽  
Takuto Maeda
Keyword(s):  
Wave Propagation ◽  
High Resolution ◽  
Time Reversal ◽  
Source Parameters ◽  
Strong Motion ◽  
Source Image ◽  
Fast Time ◽  
Source Imaging ◽  
Large Earthquakes ◽  
Seismograph Network

Summary This paper describes an efficient approach to high-resolution time-reversal source imaging simulation. Dense seismograph network records are back-propagated from stations to the hypocenter through a 3D subsurface structure model to estimate the initial source wavefield at the earthquake initiation time. By assimilating high-density observational data into the time-reversal wave propagation, a clearer source image can be determined, even for deep and distant earthquakes, than is achievable with conventional source imaging. The effectiveness of data-assimilation-based source imaging by a time-reversal wave propagation simulation with a 3D heterogeneous structural model was demonstrated using recordings from a nationwide strong-motion seismograph network during the 2007 Off Niigata, Japan, Mw 6.6 earthquake, and the 2007 Off Ibaraki, Japan, Mw 6.8 earthquake. Such data-assimilated-based simulations are also effective for early forecasting of strong ground motions caused by large earthquakes through fast time-advancing simulations based on the current assimilated wavefield. We will discuss the feasibility of a disaster prevention system for the early forecasting of strong motion disasters due to large earthquakes, based on repeatedly estimating source parameters and forecasting strong motions in future time based on the current assimilated wavefields.

scholarly journals A workflow for streamlined acquisition and correlation of serial regions of interest in array tomography

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Sergio Gabarre ◽  
Frank Vernaillen ◽  
Pieter Baatsen ◽  
Katlijn Vints ◽  
Christopher Cawthorne ◽  
...  
Keyword(s):  
High Resolution ◽  
Light And Electron Microscopy ◽  
User Interaction ◽  
Regions Of Interest ◽  
Imaging Method ◽  
Array Tomography ◽  
Reference Space ◽  
Cell Processes ◽  
Electron Microscopes ◽  
Specific Tissue

Abstract Background Array tomography (AT) is a high-resolution imaging method to resolve fine details at the organelle level and has the advantage that it can provide 3D volumes to show the tissue context. AT can be carried out in a correlative way, combing light and electron microscopy (LM, EM) techniques. However, the correlation between modalities can be a challenge and delineating specific regions of interest in consecutive sections can be time-consuming. Integrated light and electron microscopes (iLEMs) offer the possibility to provide well-correlated images and may pose an ideal solution for correlative AT. Here, we report a workflow to automate navigation between regions of interest. Results We use a targeted approach that allows imaging specific tissue features, like organelles, cell processes, and nuclei at different scales to enable fast, directly correlated in situ AT using an integrated light and electron microscope (iLEM-AT). Our workflow is based on the detection of section boundaries on an initial transmitted light acquisition that serves as a reference space to compensate for changes in shape between sections, and we apply a stepwise refinement of localizations as the magnification increases from LM to EM. With minimal user interaction, this enables autonomous and speedy acquisition of regions containing cells and cellular organelles of interest correlated across different magnifications for LM and EM modalities, providing a more efficient way to obtain 3D images. We provide a proof of concept of our approach and the developed software tools using both Golgi neuronal impregnation staining and fluorescently labeled protein condensates in cells. Conclusions Our method facilitates tracing and reconstructing cellular structures over multiple sections, is targeted at high resolution ILEMs, and can be integrated into existing devices, both commercial and custom-built systems.

Computer Application in Geosciences: Imaging of the Subsurface by Structural Coupled Inversion of Potential Field Data

2014 ◽  
Vol 644-650 ◽  
pp. 2670-2673
Author(s):  
Jun Wang ◽  
Xiao Hong Meng ◽  
Fang Li ◽  
Jun Jie Zhou
Keyword(s):  
Potential Field ◽  
Field Data ◽  
Gravity Data ◽  
Computer Application ◽  
Magnetic Data ◽  
Imaging Method ◽  
Inversion Algorithm ◽  
Constant Property ◽  
Near Surface ◽  
Potential Field Data

With the continuing growth in influence of near surface geophysics, the research of the subsurface structure is of great significance. Geophysical imaging is one of the efficient computer tools that can be applied. This paper utilize the inversion of potential field data to do the subsurface imaging. Here, gravity data and magnetic data are inverted together with structural coupled inversion algorithm. The subspace (model space) is divided into a set of rectangular cells by an orthogonal 2D mesh and assume a constant property (density and magnetic susceptibility) value within each cell. The inversion matrix equation is solved as an unconstrained optimization problem with conjugate gradient method (CG). This imaging method is applied to synthetic data for typical models of gravity and magnetic anomalies and is tested on field data.

High-resolution MEG source imaging approach to accurately localize Broca’s area in patients with brain tumor or epilepsy

2016 ◽  
Vol 127 (5) ◽  
pp. 2308-2316 ◽  
Author(s):  
Charles W. Huang ◽  
Ming-Xiong Huang ◽  
Zhengwei Ji ◽  
Ashley Robb Swan ◽  
Anne Marie Angeles ◽  
...  
Keyword(s):  
Brain Tumor ◽  
High Resolution ◽  
Broca’S Area ◽  
Broca's Area ◽  
Source Imaging ◽  
Imaging Approach

An imaging method for the covered damage region of strand wire based on dual time reversal using piezoceramic transducers

2017 ◽  
Vol 26 (10) ◽  
pp. 104005 ◽  
Author(s):  
Hong Xiaobin ◽  
Zhou Jianxi ◽  
Lin Peisong ◽  
Huang Guojian
Keyword(s):  
Time Reversal ◽  
Imaging Method

A Method of Dispersion Compensation Based on Warped Frequency Transform

2013 ◽  
Vol 718-720 ◽  
pp. 2062-2067 ◽  
Author(s):  
Shang Chen Fu ◽  
Zhen Jian Lv ◽  
Ding Ma ◽  
Li Hua Shi
Keyword(s):  
High Resolution ◽  
Velocity Dispersion ◽  
Lamb Waves ◽  
Group Velocity Dispersion ◽  
Dispersion Compensation ◽  
Imaging Method ◽  
Finite Element Software ◽  
Damage Imaging ◽  
Resolution Imaging ◽  
Multi Mode

The use of Lamb waves for structural health monitoring (SHM) has complicated by its multi-mode character and dispersion effect, which impacts the damage positioning and high-resolution imaging. The group velocity dispersion curves of Lamb waves can be employed to warp the frequency axis, and then to establish warped frequency transform (WFT) to process Lamb waves. In this paper, received signals are directly compensated with warped frequency transform to suppress dispersion, and a new imaging method is proposed based on warped frequency transform. The propagation of Lamb waves in damaged aluminum plate is simulated by finite element software ABAQUS, results show that warped frequency transform can effectively compensate dispersive wave-packets, and high-resolution damage imaging can be obtained by the proposed method.

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