A5064056753- Seismic Waves and Analysis
- Seismic Imaging and Inversion Techniques
- Drilling and Well Engineering
- Geophysical Methods and Applications
- Hydraulic Fracturing and Reservoir Analysis
- Seismology and Earthquake Studies
- Cryospheric studies and observations
- earthquake and tectonic studies
- Ultrasonics and Acoustic Wave Propagation
- Underwater Acoustics Research
- Landslides and related hazards
- Advanced Fiber Optic Sensors
- Geophysics and Sensor Technology
- Arctic and Antarctic ice dynamics
- High-pressure geophysics and materials
- Railway Engineering and Dynamics
- Simulation Techniques and Applications
- Speech and Audio Processing
- Geological and Geochemical Analysis
- Earthquake Detection and Analysis
- Reservoir Engineering and Simulation Methods
- Climate change and permafrost
- Embedded Systems Design Techniques
- International Student and Expatriate Challenges
- Rock Mechanics and Modeling
Institute of Geodesy and Geophysics
2022-2024
Chinese Academy of Sciences
2022-2024
Pacific Northwest National Laboratory
2023
Los Alamos National Laboratory
2017-2021
Rice University
2020-2021
University of Wisconsin–Madison
2020
Tongji University
2012-2018
State Key Laboratory of Marine Geology
2015
Abstract The sparsity of permanent seismic instrumentation in marine environments often limits the availability subsea information on geohazards, including active fault systems, both time and space. One sensing resource that provides observational access to seafloor environment are existing networks ocean bottom fiber optic cables; these cables, coupled modern distributed acoustic (DAS) can provide dense arrays broadband observations capable recording events ambient noise wavefield. Here, we...
Because modeling for full-waveform inversion (FWI) cannot produce reflections unless the velocity model has scattering potential (high wavenumbers), using a migration/demigration process to generate data, which is key step in what now known as reflection FWI (RFWI), credible alternative tackle nonlinearity associated with FWI. However, because RFWI depends on conventional data residual or zero-lag correlation objective function, high can still exist when true amplitude migration not used,...
This paper proposes an improvement on the scattering-integral (SI) approach for acoustic frequency-domain full waveform inversion (FWI) based individual Born kernels. The main development is a method calculating steepest-descent direction and pseudo-Newton by vector operations with definite physical meaning, without needing to store huge Fréchet kernels in memory beforehand. Gauss–Newton descent can therefore be iteratively constructed approximate Hessian matrix or calculate its inverse....
Abstract Understanding mechanisms controlling fluid injection-triggered seismicity is key in defining strategies to ameliorate it. Recent triggered events (e.g. Pohang, Mw 5.5) have exceeded predictions of average energy release by a factor >1000x, necessitating robust methodologies both define critical antecedent conditions and thereby constrain anticipated event size. We maximum magnitudes resulting from triggering as function pre-existing stresses injection volume. Fluid experiments on...
Abstract The Imperial Valley is a seismically active basin occupying the southern end of Salton trough, an area rapid extension, high heat flow, and abundant geothermal resources. This report describes ongoing large-scale distributed acoustic sensing (DAS) recording study acquiring high-density seismic data on array between Calipatria Imperial, California. 27 km array, operating dark fiber since 9 November 2020, has recorded wealth local events as well ambient noise. goal broader Dark Fiber...
Abstract The Southern San Andreas Fault (SSAF) in California is one of the most thoroughly studied faults world, but its configuration at seismogenic depths remains enigmatic Coachella Valley. We use a combination space geodetic and seismic observations to demonstrate that relatively straight southernmost section SSAF, between Thousand Palms Bombay Beach, dipping northeast 60–80° throughout upper crust (<10 km), including shallow aseismic layer. constrain fault attitude top 2–3 km using...
Fracture injection/shut-in tests are commonly used to measure the state of stress in subsurface. Injection creates a hydraulic fracture (or some cases, opens preexisting fracture), and then pressure after shut-in is monitored identify closure. Different interpretation procedures have been proposed for estimating closure, sometimes yield significantly different results. In this study, direct, in-situ strain measurements observe reopening The were performed as part EGS Collab project,...
Distributed acoustic sensing (DAS) is a novel seismological observation technology based on the fiber-optic method, and can transform existing urban cables into ultra-dense array for researches, thus opening abundant opportunities resolving fine details of near surface structures. While high frequency ambient noise recorded DAS has been applied in wave tomography, it often difficult to extract clear dispersion curve data by internet cable because effect precursor signals correlation...
Full waveform inversion has been a successful tool to build high resolution velocity models, but it suffers from local minima problem. We propose an envelope based method allowing the updating of long wavelength components model. The gradient misfit function can be efficiently computed through adjoint-state technique. use simple models prove that objective is more convex than traditional FWI and not as sensitive frequency data FWI. Finally we compare new approach application on 2D synthetic...
The importance of railway safety cannot be overemphasized; hence it requires reliable traffic monitoring systems. Widespread trackside telecommunication fiber-optic cables can suitably deployed in the form dense vibration sensors using Distributed Acoustic Sensing technology (DAS). Train-induced ground motion signals are recorded as continuous “footprints” DAS recordings. As system records huge datasets, is thus imperative to develop optimized/stable algorithms which used for accurate...
Abstract We provide high‐resolution seismic imaging of the central Garlock fault using data recorded by two dense arrays that cross Ridgecrest rupture zone (B4) and (A5). Analyses head waves P ‐wave delay times at array A5 show is a sharp bimaterial interface with traveling ∼5% faster in northern crustal block. The across‐fault velocity contrast agrees regional tomography models generates clear reflections waveforms B4. Kirchhoff migration reflected indicates near‐vertical between 2 6 km...
The effective monitoring of hydraulic fracturing in unconventional oil and gas production requires tools to quantify elastic property variations even the absence microseismic activity. To track subtle time-lapse reservoir properties during such activities, techniques with high repeatability resolution, spatially temporally, are required. Distributed acoustic sensing (DAS) is a rapidly maturing fiber-optic technology for low-cost, permanent, density, in-well monitoring. Surface orbital...
Abstract. Studying seismic sources and wave propagation in ice plates can provide valuable insights into understanding various processes, such as structure dynamics, migration, fracture mechanics mass balance. However, the harsh environment makes it difficult to conduct situ dense observations. Consequently, our of dynamic changes within sheet remains insufficient. We conducted a experiment using distributed acoustic sensing (DAS) array on frozen lake, exciting water vibrations through...
Full-waveform inversion (FWI) has become a powerful tool for high-resolution velocity building. However, FWI suffers from the local-minima problem, particularly when both initial model is inaccurate and low-frequency data are absent. To alleviate this problem improve convergence rate, we develop new full-waveform method using least-squares reverse-time migration (LSRTM) to guide interface updates an efficient, implicit wavefield separation scheme alternatively update low-wavenumber...
SUMMARY Seismicity induced by fluid injection including wastewater injection, hydrofracking and enhanced geothermal system (EGS) site production draws public attention. Dense arrays have been deployed to improve monitoring capability. In 2016 March, the PoroTomo experiment an 8.6-km-long fibre-optic cable for distributed acoustic sensing (DAS) in field at Brady Hot Springs, Nevada, covering area of 1.5 0.5 km. The goal was assess integrated technology characterizing temporal changes rock...
Abstract The main difficulty in seismic full waveform inversion (FWI) is the strong nonlinearity, which caused by complexity of wave propagation. Different components elastic parameters result different characteristics data. Meanwhile, quality required stages exploration or exploitation. So, there no need to pursue matching all information during inversion. Some problems can be solved part and nonlinearity also avoided this way. According consideration, a generalized FWI strategy method...
Abstract The main difficulty in seismic full‐waveform inversion is the strong nonlinearity of these waveforms, which caused by complexity wave propagation. Analysis objective‐function behavior and its variations with scale parameter perturbations can help us to choose an appropriate method strategy. Using Jannane et al.'s analyzing behavior, we have studied relationship between objective functions calculated from different data subsets their perturbations, especially nonlinearity. These...
Elastic least-squares reverse-time migration (ELSRTM) is emerging as an iterative full-wavefield imaging technique to produce subsurface elastic images by matching synthetic seismic data with observed multi-component data. As evolutionary version of acoustic LSRTM that inverts solely the P-wave velocity perturbation (or PP image), ELSRTM attempts generate both P- and S-wave perturbations PS images) simultaneously. Most current methods rely on Born modeling framework. We develop a novel...
In this paper, based on the acoustic Born kernel, we propose a flexible method to calculate gradient and approximate Hessian in frequency-domain full waveform inversion (FWI) by matrix decomposition. method, neither kernel nor is necessarily stored memory. We name FWI using as decomposition (MDFWI). Most of calculation MDFWI depends forward modeling from sources unrepeated receivers frequency domain. For first order direction, good replacement adjoint-state (ADFWI) when source number ns more...
ABSTRACT Reflection full waveform inversion can update subsurface velocity structure of the deeper part, but tends to get stuck in local minima associated with misfit function. These cause cycle skipping if initial background model is far from true model. Since conventional reflection using two‐way wave equation time domain computationally expensive and consumes a large amount memory, we implement correlation‐based one‐way equations retrieve velocity. In this method, are used for seismic...
Full-waveform inversion is a promising tool to produce accurate and high-resolution subsurface elastic models. Accurate estimation of the source wavelet required for most full-waveform algorithms obtain reliable results. We develop novel source-independent waveform method avoid in inversion. define an amplitude-semblance objective function remove effect. Compared with other FWI methods, our new does not require optimized reference trace. Meanwhile, approach can better handle inconsistence...