Optimization of the array mirror for time reversal techniques used in a half-space environment

Harker, Blaine M.; Anderson, Brian E.

doi:10.1121/1.4798268

Cited by 13 publications

(28 citation statements)

References 15 publications

(15 reference statements)

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“…An explosion source (only M xx = M yy = M zz were non-zero) or a strike-slip source (only M xy was non-zero) was used. As a source signal, the negative normalized 15 second derivative of the Gaussian function, also called a Ricker wavelet, was used. The Ricker wavelet was implemented, following Shearer (2009), as…”

Section: Simulation Of Wave Propagation In Elastic Mediamentioning

confidence: 99%

“…4. We were able to 15 localize a strike-slip source in 5 km depth with nine receivers placed 1 to 9 km apart. The explosion source in 5 km depth was localized reliably with an inter-station distance of 6 km.…”

Section: Minimum Aperture and Maximum Inter-station Distancementioning

confidence: 99%

“…When using nine receivers there was no reliable localization possible for both source types. With a SNR of 1 there was only one localization in category II and for SNRs down to 0.5 there were only localizations in 15 category III. When using 25 receivers it was possible to localize both source types with a SNR as low as 0.25 in category I but only with one imaging condition.…”

mentioning

confidence: 92%

“…A high level of noise in the traces may inhibit localizations with TRI, even when the array and the velocity model are 15 sufficiently well. In theory, TRI works even with a very low signal-to-noise ratio because noise is random and will not superpose constructively to form a focus during the backpropagation of the wavefield.…”

Section: Introductionmentioning

confidence: 99%

“…To determine which simulation setups will produce reliable localizations, the simulations with localizations in category I and II should be viewed. Simulations with more than one imaging condition in category I or II were considered simulations producing 15 reliable localizations. This requirement to have two successful imaging conditions per simulation inhibits the misinterpretation of an artefact for a localization.…”

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confidence: 99%

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Obtaining reliable localizations with Time Reverse Imaging: limits to array design, velocity models and signal-to-noise ratios

Finger¹,

Saenger²

2018

Preprint

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Abstract. Time Reverse Imaging (TRI) is evolving into a standard technique for localizing and characterizing seismic events. In recent years, TRI has been applied to a wide range of applications from the lab scale over the field scale up to the global scale. No identification of events and their onset times is necessary when localizing events with TRI. Therefore, it is especially suited for localizing quasi-simultaneous events and events with a low signal-to-noise ratio. However, in contrast to more regularly applied localization methods, the prerequisites for applying TRI are not sufficiently known. To investigate the significance of station distributions, complex velocity models and signal-to-noise ratios for the localization quality, numerous simulations were performed using a finite difference code to propagate elastic waves through three-dimensional models. Synthetic seismograms were reversed in time and re-inserted into the model. The time-reversed wavefield backpropagates through the model and, in theory, focuses at the source location. This focusing was visualized using imaging conditions. Additionally, artificial focusing spots were removed with an illumination map specific to the setup. Successful localizations were sorted into four categories depending on their reliability. Consequently, individual simulation setups could be evaluated by their ability to produce reliable localizations. Optimal inter-station distances, minimum apertures, relations between array and source location, heterogeneities of inter-station distances and total number of stations were investigated for different source depth as well as source types. Additionally, the quality of the localization was analysed when using a complex velocity model or a low signal-to-noise ratio. Finally, an array in Southern California was investigated for its ability to localize seismic events in specific target depths while using the actual velocity model for that region. In addition, the success rate with recorded data was estimated. Knowledge about the prerequisites for using TRI enables the estimation of success rates for a given problem. Furthermore, it reduces the time needed for adjusting stations to achieve more reliable localizations and provides a foundation for designing arrays for applying TRI.

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Section: Simulation Of Wave Propagation In Elastic Mediamentioning

confidence: 99%

Section: Minimum Aperture and Maximum Inter-station Distancementioning

confidence: 99%

mentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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