A modified delay-time method for statics estimation with the virtual refraction

Mikesell, T. Dylan; Wijk, Kasper van; Ruigrok, Elmer; Lamb, Andrew P.; Blum, Thomas

doi:10.1190/geo2012-0111.1

Cited by 14 publications

(5 citation statements)

References 17 publications

(17 reference statements)

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“…The observed signals also compare well with an active source gather. Mikesell et al (2012) developed a "modified delay-time method," wherein they estimate receiver-side delay times and isolate the arrival times of the virtual refraction.…”

Section: General Overviewmentioning

confidence: 99%

Three-dimensional supervirtual seismic refraction interferometry

Edigbue

Al-Shuhail

2016

Arab J Geosci

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Section: General Overviewmentioning

confidence: 99%

Three-dimensional supervirtual seismic refraction interferometry

Edigbue

Al-Shuhail

2016

Arab J Geosci

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“…Examples of commonly used window-based energy-ratio algorithms include the short-and long-time average ratio (STA/LTA) [36][37][38] and the modified energy ratio (MER) [39][40][41]. The STA window is sensitive to rapid fluctuations in the amplitude of the time series, while the LTA window provides information about the background noise.…”

Section: Itase-01-3b Firn Corementioning

confidence: 99%

Laser Ultrasound Observations of Mechanical Property Variations in Ice Cores

et al. 2017

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Abstract:The study of climate records in ice cores requires an accurate determination of annual layering within the cores in order to establish a depth-age relationship. Existing tools to delineate these annual layers are based on observations of changes in optical, chemical, and electromagnetic properties. In practice, no single technique captures every layer in all circumstances. Therefore, the best estimates of annual layering are produced by analyzing a combination of measurable ice properties. We present a novel and complimentary elastic wave remote sensing method based on laser ultrasonics. This method is used to measure variations in ultrasonic wave arrival times and velocity along the core with millimeter resolution. The laser ultrasound system does not require contact with the ice core and is non-destructive. Custom optical windows allow the source and receiver lasers to be located outside the cold room, while the core is scanned by moving it with a computer-controlled stage. We present results from Antarctic firn and ice cores that lack visual evidence of a layered structure, but do show travel-time and velocity variations. In the future, these new data may be used to infer stratigraphic layers from elastic parameter variations within an ice core, as well as analyze ice crystal fabrics.

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“…Mikesell et al . () used a 2D model with varying surface‐layer thicknesses to calculate the virtual refraction statics. Consider the two‐layer acoustic model with different velocity and density parameters shown in Fig.…”

Section: Synthetic Data Examplementioning

confidence: 99%

“…When the time-windowed wavefields include other interfering events, we can apply FK filtering or median filtering to eliminate their influence. Mikesell et al (2012) used a 2D model with varying surfacelayer thicknesses to calculate the virtual refraction statics. Consider the two-layer acoustic model with different velocity and density parameters shown in Fig.…”

Section: Super-virtual Refraction Interferometry By Cross-correlationmentioning

confidence: 99%

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Retrieval of super‐virtual refraction by cross‐correlation

Qiao

Guo

Wang

et al. 2014

Geophysical Prospecting

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Topography and severe variations of near‐surface layers lead to travel‐time perturbations for the events in seismic exploration. Usually, these perturbations could be estimated and eliminated by refraction technology. The virtual refraction method is a relatively new technique for retrieval of refraction information from seismic records contaminated by noise. Based on the virtual refraction, this paper proposes super‐virtual refraction interferometry by cross‐correlation to retrieve refraction wavefields by summing the cross‐correlation of raw refraction wavefields and virtual refraction wavefields over all receivers located outside the retrieved source and receiver pair. This method can enhance refraction signal gradually as the source–receiver offset decreases. For further enhancement of refracted waves, a scheme of hybrid virtual refraction wavefields is applied by stacking of correlation‐type and convolution‐type super‐virtual refractions. Our new method does not need any information about the near‐surface velocity model, which can solve the problem of directly unmeasured virtual refraction energy from the virtual source at the surface, and extend the acquisition aperture to its maximum extent in raw seismic records. It can also reduce random noise influence in raw seismic records effectively and improve refracted waves’ signal‐to‐noise ratio by a factor proportional to the square root of the number of receivers positioned at stationary‐phase points, based on the improvement of virtual refraction's signal‐to‐noise ratio. Using results from synthetic and field data, we show that our new method is effective to retrieve refraction information from raw seismic records and improve the accuracy of first‐arrival picks.

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A modified delay-time method for statics estimation with the virtual refraction

Cited by 14 publications

References 17 publications

Three-dimensional supervirtual seismic refraction interferometry

Three-dimensional supervirtual seismic refraction interferometry

Laser Ultrasound Observations of Mechanical Property Variations in Ice Cores

Retrieval of super‐virtual refraction by cross‐correlation

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