Performance of time-delay estimators

Bagaini, Claudio

doi:10.1190/1.1996909

Cited by 7 publications

(7 citation statements)

References 18 publications

(22 reference statements)

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“…We use the multichannel cross correlation method (MCCC; VanDecar and Crosson 1990) to calculate the relative arrival time to correct the travel time. As shown by Bagaini (2005), MCCC is often the best approach for noisy data and is less prone to cycle skipping. Equation 6 in VanDecar and Crosson (1990) is used for calculating the delay times for each station, which is equivalent to the average of the time shifts measured relative to the other stations.…”

Section: Methodsmentioning

confidence: 97%

Source characteristics of the deep Philippine earthquake cluster, 23 and 24 July 2010

Zhang

2012

J Seismol

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We determine the rupture velocity, rupture area, stress drop and duration of four strong deepfocus earthquakes in the Philippines by backprojecting the teleseismic P waves. Four deep-focus earthquakes occurred in a totally consumed Molucca microplate; their focal depths were greater than 550 km and their moment magnitudes were between M w 6.6 and M w 7.6. By studying this deep-focus cluster, we are able to estimate the rupture velocity, rupture area and stress drop which would assist in constraining the physical mechanism for earthquakes deeper than 500 km. Since the Molucca microplate is totally consumed, little evidence is left on the surface for us to do research. This deep-focus cluster provides us the opportunity to reveal the properties of this totally consumed microplate by using seismic method for the first time. Four earthquakes in this deep-focus cluster all have multiple rupture subevents. The M w 7.3 event ruptures in two subevents, the M w 7.6 and M w 7.4 events both have three subevents. The M w 6.6 event has single peak on the amplitude as a function of time; however, its energy releases at two spatially separated areas. Our results show that this deep-focus cluster has a slow rupture velocity which is about 0.27 to 0.43 of the shear wave velocity, long-scaled duration, concentrated energy release area, and high stress drop. These source properties are similar to those of other deep earthquakes occurring in warm slabs and indicate that the totally consumed Molucca microplate possibly is a warm plate.

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Section: Methodsmentioning

confidence: 97%

Source characteristics of the deep Philippine earthquake cluster, 23 and 24 July 2010

Zhang

2012

J Seismol

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“…The following form can be assumed for the microseismic data recorded at two different receivers (Bagaini, 2005)…”

Section: Iterative Cross-correlation Based Workflowmentioning

confidence: 99%

“…The time delay is estimated from the lag at the peak value of the cross correlation between x 1 (t) and x 2 (t). Bagaini (2005) evaluated the performance of different time-delay estimators where reference traces obtained from various selection schemes are used. It is shown that the iteratively updating the reference signal provides better time-delay estimation than non-iterative schemes where reference trace is selected from sensors within the array or by simple stacking.…”

Section: Iterative Cross-correlation Based Workflowmentioning

confidence: 99%

“…On the other hand, a multichannel algorithm takes advantage of the similarity of detected P-and S-wave microseismic signals for different sensors, and thus can improve the quality of time-picks. Cross-correlation is an example of a multi-channel algorithm that is widely used for time-delay estimation in electrical engineering (Tamim and Ghani, 2009), in the estimation of static corrections for surface seismic data (Bagaini, 2005) and in microseismic and earthquake data processing for event identification and phase arrival picking (Raymer et al, 2008;De Meersman et al, 2009;Eisner et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Refinement of Arrival-time Picks Using an Iterative, Cross-correlation Based Workflow

Akram¹,

Eaton²

2014

Proceedings

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Cross-correlation based techniques are widely used for time-delay estimation in electrical engineering and in the processing of passive and active seismic data. We present an iterative cross-correlation based workflow to refine arrival time picks on microseismic data that were initially picked either manually or using a single-trace based algorithm such as short and long-term average ratio (STA/LTA). We then evaluate the performance of this workflow on both synthetic and real microseismic data using a Monte Carlo approach. The proposed workflow provides an arrival-time accuracy of •±0.5 − 1ms for both synthetic and real microseismic data examples considered in this study.

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“…In this view, frequency-dependent delays or phase shifts are considered to Manuscript degrade the estimate of τ, as a consequence of imperfect coupling of the seismometer with the ground, of intrinsic attenuation, or of nearsurface reverberations. We refer to Bagaini (2005) for an extensive review of the performance of crosscorrelation estimation methods with this view in mind. Others have attempted to force crosscorrelation delay times to approach the classical onset times by giving more weight to the early part of the seismogram (Woodward and Masters, 1991).…”

Section: Introductionmentioning

confidence: 99%

Cross-borehole tomography with correlation delay times

Mercerat¹,

Nolet

Zaroli

2014

GEOPHYSICS

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We evaluated a comprehensive numerical experiment of finitefrequency tomography with ray-based ("banana-doughnut") kernels that tested all aspects of this method, starting from the generation of seismograms in a 3D model, the window selection, and the crosscorrelation with seismograms predicted for a background model, to the final regularized inversion. In particular, we tested if the quasilinearity of crosscorrelation delays allowed us to forego multiple (linearized) iterations in the case of strong reverberations characterizing multiple scattering and the gain in resolution that can be obtained by observing body-wave dispersion. Contrary to onset times, traveltimes observed by crosscorrelation allowed us to exploit energy arriving later in the time window centered in the P-wave or any other indentifiable ray arrival, either scattered from, or diffracted around, lateral heterogeneities. We tested using seismograms calculated by the spectral element method in a cross-borehole experiment conducted in a 3D checkerboard cube. The use of multiple frequency bands allowed us to estimate body-wave dispersion caused by diffraction effects. The large velocity contrast (10%) and the regularity of the checkerboard pattern caused severe reverberations that arrived late in the crosscorrelation windows. Nevertheless, the model resulting from the inversion with a data fit with reduced χ 2 red ¼ 1 resulted in an excellent correspondence with the input model and allowed for a complete validation of the linearizations that lay at the basis of the theory. The use of multiple frequencies led to a significant increase in resolution. Moreover, we evaluated a case in which the sign of the anomalies in the checkerboard was systematically reversed in the ray-theoretical solution, a clear demonstration of the reality of the "doughnut-hole" effect. The experiment validated finite-frequency theory and disqualified ray-theoretical inversions of crosscorrelation delay times.

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Performance of time-delay estimators

Cited by 7 publications

References 18 publications

Source characteristics of the deep Philippine earthquake cluster, 23 and 24 July 2010

Source characteristics of the deep Philippine earthquake cluster, 23 and 24 July 2010

Refinement of Arrival-time Picks Using an Iterative, Cross-correlation Based Workflow

Cross-borehole tomography with correlation delay times

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