Localization of seismic events in 3D media by diffraction stacking

Zhebel, V. M.; Gajewski, D.; Vanelle, C.

doi:10.3997/2214-4609.20145296

Cited by 5 publications

(4 citation statements)

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“…Therefore, by analyzing each snap shot (time slice), we can detect source locations. A similar idea was suggested by Zhebel, Gajewski and Vanelle () in their diffraction stacking algorithm. Unlike migration methods, the TR does not require knowledge of the excitation time of a source and accounts for multiple scattering.…”

Section: Introductionmentioning

confidence: 82%

Wave refocusing for linear diffractor using the time‐reversal principle

Keydar

Landa

2019

Geophysical Prospecting

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A B S T R A C TOne of the problems encountered in a variety of near-surface investigations is detecting and mapping localized heterogeneities. The heterogeneities may be classified under two kinds of objects: (1) a point diffractor that can be considered as an approximation of a small quasi-isometric, such as small karstic cavities and caves; (2) a linear diffractor roughly approximating an elongated object, such as a tube or fault plane. The point and linear diffractors generate two types of seismic diffraction: tip and edge waves, respectively. During the last few decades, different methods were proposed by many researchers for detecting these heterogeneities utilizing seismic waves diffracted by them. An alternative method for detecting point diffractors using a time-reversal principle combined with focusing analysis is proposed in this study: we present an extension of the time-reversal method for linear diffractors. It consists of a coherent summation of seismic energy along edge-diffraction traveltimes. Real data examples show the feasibility and efficiency of the proposed method.

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Section: Introductionmentioning

confidence: 82%

Wave refocusing for linear diffractor using the time‐reversal principle

Keydar

Landa

2019

Geophysical Prospecting

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“…After the publication of the original SSA paper (Kao & Shan 2004), a series of similar DSM‐based methods have been proposed in the literature to delineate the characteristics of seismic sources without performing phase picking (e.g. Baker et al 2005; Ishii et al 2005; Gajewski et al 2007; Kao & Shan 2007; Rentsch et al 2007; Anikiev et al 2009; Kan et al 2010; Zhebel et al 2010; Kao et al 2012). In fact, locating seismic sources without phase picking has been a focus of research since the early 1980s when seismological research entered the digital era with increasingly powerful computation, communication and storage capabilities (e.g.…”

Section: Discussionmentioning

confidence: 99%

Delineating complex spatiotemporal distribution of earthquake aftershocks: an improved Source-Scanning Algorithm

Liao

Kao

Rosenberger

et al. 2012

Geophysical Journal International

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SUMMARY Conventional earthquake location methods depend critically on the correct identification of seismic phases and their arrival times from seismograms. Accurate phase picking is particularly difficult for aftershocks that occur closely in time and space, mostly because of the ambiguity of correlating the same phase at different stations. In this study, we introduce an improved Source‐Scanning Algorithm (ISSA) for the purpose of delineating the complex distribution of aftershocks without time‐consuming and labour‐intensive phase‐picking procedures. The improvements include the application of a ground motion analyser to separate P and S waves, the automatic adjustment of time windows for ‘brightness’ calculation based on the scanning resolution and a modified brightness function to combine constraints from multiple phases. Synthetic experiments simulating a challenging scenario are conducted to demonstrate the robustness of the ISSA. The method is applied to a field data set selected from the ocean‐bottom‐seismograph records of an offshore aftershock sequence southwest of Taiwan. Although visual inspection of the seismograms is ambiguous, our ISSA analysis clearly delineates two events that can best explain the observed waveform pattern.

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“…In this final part of the paper, we seek to support the notion that both versions of each operator may not only be jointly utilized, but that the velocity-shift mechanism's characteristic dependence on the reference time t 0 is also advantageous for certain applications. In the context of passive seismic monitoring or earthquake seismology, the localization of the unknown source of a seismic event is a fundamental problem and may be approached with the data-driven method of diffraction stacking (Zhebel et al, 2011). For confining the source's horizontal position, description of moveout is sufficient and the reference time, according to the time shift mechanism, may be chosen arbitrarily.…”

Section: Passive Event Localizationmentioning

confidence: 99%

A generalized view on normal moveout

Schwarz

Gajewski

2017

GEOPHYSICS

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Although in the past, in the context of stacking, traveltime moveout was only formulated in individual common-midpoint (CMP) gathers, multiparameter stacking uses normal moveout (NMO) approximations that span several neighboring CMPs. Multiparameter expressions such as the common reflection surface (CRS) or multifocusing are parameterized in terms of local slopes and curvatures of emerging wavefronts rather than effective velocities, which makes these approaches appear conceptually different from conventional velocity analysis. As a consequence, the unifying nature of multiparameter NMO is still not well-appreciated. In addition, CRS and multifocusing show distinctly different behavior in that they respond differently to the overburden heterogeneity and curvature of the target interface, and they either are or are not susceptible to moveout stretch. In our work, we seek to demystify the wavefront picture by demonstrating that the conventional and multidimensional NMO operators can conveniently be derived from the same auxiliary straight-ray geometry, either representing the optical projection or formulated in an effective replacement medium. Following the early work of de Bazelaire, we suggest a simple transformation between both domains and introduce generalized dual representations of the hyperbolic CRS, multifocusing, and the two recently introduced double-square-root expressions implicit CRS and nonhyperbolic CRS. In addition, we evaluate a generalized finite-offset NMO expression that can likewise be applied to active-source diffraction data and passive seismic events. Synthetic examples suggest unification, conveniently explain the origin of moveout stretch, and indicate that the joint use of different NMO approximations offers new insight into the character and origin of different wavefield components.

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Localization of seismic events in 3D media by diffraction stacking

Cited by 5 publications

References 0 publications

Wave refocusing for linear diffractor using the time‐reversal principle

Wave refocusing for linear diffractor using the time‐reversal principle

Delineating complex spatiotemporal distribution of earthquake aftershocks: an improved Source-Scanning Algorithm

A generalized view on normal moveout

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