Reduced amplitude and distorted dispersion of seismic waves caused by attenuation, especially strong always degrades the resolution migrated images. To improve image resolution, we evaluated a methodology compensating for attenuation ([Formula: see text]) effects in reverse-time migration text]-RTM). The [Formula: text]-RTM approach worked mitigating phase source receiver wavefields. Source wavefields were extrapolated using previously published time-domain viscoacoustic wave equation that...

We evaluated a time-domain wave equation for modeling acoustic propagation in attenuating media. The was derived from Kjartansson’s constant-[Formula: see text] constitutive stress-strain relation combination with the mass and momentum conservation equations. Our equation, expressed by second-order temporal derivative two fractional Laplacian operators, described very nearly attenuation dispersion effects. advantage of using our formulation Laplacians over traditional time approach avoidance...

A constant-[Formula: see text] wave equation involving fractional Laplacians was recently introduced for viscoacoustic modeling and imaging. This has a convenient mixed-domain space-wavenumber formulation, which involves the fractional-Laplacian operators with spatially varying power. We have applied low-rank approximation to symbol, enables space-variable attenuation specified by variable power of Laplacians. Using proposed scheme, we formulated framework [Formula: text]-compensated reverse...

ABSTRACT In this study, we investigate the accuracy of approximating constant‐ Q wave propagation by series Zener or standard linear solid (SLS) mechanisms. Modelling in viscoacoustic and viscoelastic media is implemented time domain using finite‐difference (FD) method. The numerical solutions evaluated comparison with analytical solution homogeneous media. We found that FD three SLS relaxation mechanisms as well a single mechanism, properly chosen times, are quite accurate for both weak...

We derive a time-domain differential equation for modelling seismic wave propagation in constant-Q viscoelastic media based on fractional spatial derivatives, specifically Laplacian operators of order. The stress–strain relation is derived from the classical expressed terms time derivatives. new formulation has advantage not requiring additional field variables that increase computer and storage significantly. derivatives are calculated with generalization Fourier pseudospectral method to...

Attenuation of seismic waves needs to be taken into account improve the accuracy imaging. In viscoacoustic media, reverse time migration (RTM) can performed with [Formula: see text]-compensation, which is also known as text]-RTM. Least-squares RTM (LSRTM) has been shown able compensate for attenuation through linearized inversion. However, may significantly slow down convergence rate least-squares iterative inversion process without proper preconditioning. We have found that incorporating...

Abstract. Continuous seismic monitoring of the Earth's near surface (top 100 m), especially with improved resolution and extent data both in space time, would yield more accurate insights about effect extreme-weather events (e.g., flooding or drought) climate change on subsurface systems. However, continuous long-term monitoring, urban areas, remains challenging. We describe Fiber Optic foR Environmental SEnsEing (FORESEE) project Pennsylvania, USA, first continuous-monitoring distributed...

First arrival time picking is one of the critical processing steps acoustic emission (AE)/microseismic (MS) monitoring for studying rock fracture processes. Because massive data, automatic technique particularly desired. Inspired by recent successful applications machine learning (ML) in earthquake phase identification, we propose a deep (DL)-based P-wave first method named AE Network (AEnet) laboratory data. Our approach consists two steps: classification and picking. The convolutional...

Abstract Seismic velocity and attenuation anisotropy are ubiquitous in the crust upper mantle, significantly modulating characteristics of seismic wave propagation Earth's interior. Accurate modeling is essential for understanding interior as well constructing global region‐scale full waveform tomography. Here, we derive a decoupled fractional Laplacian (DFL) viscoelastic equation to characterize frequency‐independent Q behavior vertical transversely isotropic (VTI) media. We verify accuracy...

Abstract During the past few years, distributed acoustic sensing (DAS) has become an invaluable tool for recording high-fidelity seismic wavefields with great spatiotemporal resolutions. However, considerable amount of data generated during DAS experiments limits their distribution broader scientific community. Such a bottleneck inherently slows down pursuit new discoveries in geosciences. Here, we introduce PubDAS—the first large-scale open-source repository where several datasets from...

SUMMARY Time-reverse modelling (TRM) of acoustic wave propagation has been widely implemented in seismic migration and time-reversal source imaging. The basic assumption this is that the equation time-invariant non-attenuating media. In Earth, attenuation often invalidates time-invariance. To overcome problem, I propose a TRM approach compensates for dispersion effects during attenuating This based on viscoacoustic which explicitly separates following constant-Q model. Compensating achieved...

Abstract We report for the first time on a distributed acoustic sensing (DAS) array using preexisting underground fiber optics beneath Penn State campus detecting and characterizing thunder‐induced ground motions. During half‐hour interval from 03:20–03:50 UTC 15 April 2019 in College, PA, we identify 18 seismic events DAS data. The high‐fidelity data show that seismics are very broadband, with their peak frequency ranging 20 to 130 Hz. use arrival times of estimate phase velocity near...

Seismic anisotropy is the fundamental phenomenon of wave propagation in earth’s interior. Numerical modeling behavior critical for exploration and global seismology studies. The full elastic (anisotropy) equation often used to model complexity velocity anisotropy, but it ignores attenuation anisotropy. I have presented a time-domain displacement-stress formulation anisotropic-viscoelastic equation, which holds arbitrarily anisotropic [Formula: see text]. frequency-independent text]...

The calculation of the gradient in full-waveform inversion (FWI) usually involves crosscorrelating forward-propagated source wavefield and back-propagated data residual at each time step. In real earth, propagating waves are typically attenuated due to viscoelasticity, which results an for FWI. Replacing true with a [Formula: see text]-compensated can accelerate convergence rate process. We have used phase-dispersion amplitude-loss decoupled constant-[Formula: text] wave equation formulate...

We have developed a theory of viscoelastic reverse time migration (RTM). The main feature RTM is compensation for P- and S-wave attenuation effects in seismic images during migration. forward modeling engine based on wave equation involving fractional Laplacians. Because the decoupled property, propagation can be simulated three scenarios, i.e., only amplitude loss effect, phase dispersion or both simultaneously. This separation brings practical flexibility to studying imaging. backward...

From the seismic imaging point of view, difficulty in locating passive sources lies their unknown start times. In other words, source model has an additional dimension time, which leads to extended space. Without proper preconditioning, computational cost directly inverting for functions can be intractable. Using recently proposed cross-correlation time-reversal condition, we formulate task as inverse problem, and use a sparse weighting function calculated from back-propagated events...

Accurate seismic modeling in realistic media serves as the basis of full-waveform inversion and imaging. Recently, viscoacoustic incorporating attenuation effects has been performed by solving a fractional Laplacian wave equation. In this equation, attenuation, being spatially heterogeneous, is represented partially varying power operator previously approximated global Fourier method. We have developed local-spectral approach, based on Hermite distributed approximating functional (HDAF)...

Abstract Quantifying the attenuation of seismic waves propagating in Earth interior is critical to study subsurface structure. Previous studies have proposed fractional anelastic wave equations model frequency‐independent Q propagation. Such involve derivatives that pose computational challenges for numerical schemes terms accuracy and efficiency when dealing with heterogeneous media. To tackle these challenges, here we derive a new viscoacoustic equation, where power Laplacian operators are...

Seismic data for studying the near surface have historically been extremely sparse in cities, limiting our ability to understand small-scale processes, locate geohazards, and develop earthquake hazard microzonation at scale of buildings. In recent years, distributed acoustic sensing (DAS) technology has enabled use existing underground telecommunications fibers as dense seismic arrays, requiring little manual labor or energy maintain. At Fiber-Optic foR Environmental SEnsEing array under...

Abstract Ground penetrating radar (GPR) is used to image the shallow subsurface as evident in earth and planetary exploration. Electromagnetic (EM) velocity (permittivity) models are inverted from GPR data for accurate migration. While conventional analysis methods designed multioffset data, our knowledge, zero‐offset has been underexplored. Inspired by recent deep learning seismic impedance inversion, we propose a guided technique, GPRNet, that based on convolutional neural networks...

Abstract Subsurface processes significantly influence surface dynamics in permafrost regions, necessitating utilizing diverse geophysical methods to reliably constrain characteristics. This research uses multiple techniques explore the spatial variability of undisturbed tundra and its degradation disturbed Utqiaġvik, Alaska. Here, we integrate quantitative techniques, including multichannel analysis waves (MASW), electrical resistivity tomography (ERT), ground temperature sensing, study...

Seismic attenuation, which leads to amplitude decay and phase velocity dispersion, reflects the mesoscopic heterogeneities in fluid-saturated porous media. As a result, seismic attenuation offers valuable insights into lithology of sediments. We apply 2D viscoacoustic full-waveform inversion ( Q-FWI) time-lapse data sets acquired North Sea Volve field characterize shale/sandstone sequence, oil reservoir its production-related changes. The Hessian approximated by Newton-conjugate gradient...

Summary Distributed sensor networks are designed to provide computation in-situ and in real-time. The conventional time-reversal imaging approach for microseismic event location may not be optimal such an environment. To address this challenge, we develop a methodology of locating multiple events with unknown start times based on the cross-correlation condition borrowed from active-source seismic imaging. principle states that true source must correspond where all backward-propagated...

ABSTRACT Attenuation in seismic wave propagation is a common cause for poor illumination of subsurface structures. Attempts to compensate amplitude loss images by amplifying the wavefield may boost high‐frequency components, such as noise, and create undesirable imaging artefacts. In this paper, rather than directly, we develop stable compensation operator using division. The relies on constant‐ Q equation with decoupled fractional Laplacians compensates full attenuation phenomena performing...