Broadband F‐k analysis of array data to identify sources of local scattering

Gupta, Indra N.; Lynnes, C.; Wagner, Robert A.

doi:10.1029/gl017i002p00183

Cited by 32 publications

(13 citation statements)

References 3 publications

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“…After beamforming we computed the residual seismograms, the difference between the beam and the time-aligned stations traces, for use in further studies of beam performance. Residual seismograms have also been used to identify the source of scattered arrivals (Gupta, Lynnes & Wagner 1990a;Gupta et al 1990b) from nearby structures.…”

Section: Studies Of Frequency-wavenumber Spectra and Beamformingmentioning

confidence: 99%

Array analysis of the large-aperture array of the 1988-89 PASSCAL Basin and Range Passive-Source Seismic Experiment

Randall¹,

Owens²

1994

Geophysical Journal International

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S U M M A R YThe 1988-89 PASSCAL Basin and Range Passive-Source Seismic Experiment consisted of two array deployments, the large-and small-aperture arrays. The largeaperture array consisted of seven stations with three-component mid-period seismometers, and independently triggered prototype PASSCAL data recorders with GOES clocks. The array spatial distribution and the synchronized data have permitted us to employ simple beamforming operations to improve receiver-function estimation from single teleseismic events. The beamforming reinforces the coherent teleseismic P wave and the deterministic portions of the P-wave coda, primarily generated by interactions at major lithospheric interfaces. Microseismic background noise is incoherent across the array, and is attenuated by beamforming. Beamforming also diminishes those portions of the coda due to scattering by inhomogeneities, that appear random on the scale of the array aperture. The enhanced signal-to-noise ratio of the teleseismic recording dramatically improves the single-event receiver function deconvolution results.

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Section: Studies Of Frequency-wavenumber Spectra and Beamformingmentioning

confidence: 99%

Array analysis of the large-aperture array of the 1988-89 PASSCAL Basin and Range Passive-Source Seismic Experiment

Randall¹,

Owens²

1994

Geophysical Journal International

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“…Frequency-wavenumber (FK) analysis [31] is a useful method to analyze the records of seismic array, which has the unique advantage comparing with the records of single stations [32]. The FK analysis calculates the power distributed among different slowness and direction of approach, which is able to measure the azimuth and horizontal slowness simultaneously.…”

Section: Methods and Step To Locate The Scatterersmentioning

confidence: 99%

Locating seismic scatterers at the base of the mantle beneath eastern Tibet with PKIKP precursors

Shen

Zhou

2009

Chin. Sci. Bull.

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Clear PKIKP precursors were observed from the Lanzhou CTBTO seismic array. We measured their incident angles, arriving azimuths and differential travel times with respect to the PKIKP arrivals using array analysis techniques. These measurements allowed us to locate the scatterers that generated the observed precursors. We found that the scatterers are located in the lowermost mantle beneath eastern Tibet, which is featured by a high-velocity anomaly based on previous tomographic studies. The high velocity anomaly was interpreted as the slab remnants of the ancient Tethys subduction. We thus speculate that the observed scatterers are either related or induced by the subducted slab. PKIKP precursors, scatterers, base of the mantle, Lanzhou CTBTO seismic array, Ancient TethysCitation: Shen X Z, Zhou H L. Locating seismic scatterers at the base of the mantle beneath eastern Tibet with PKIKP precursors. PKIKP (or PKPdf) precursors are frequently employed to explore the bottom of mantle or D double prime (D''). The amplitudes of the precursors before PKIKP are weak, and only are recorded in the epicentral distance range of 125°-143°. Hedlin and Shearer [1] systematically studied PKIKP precursors recorded by the Global Seismic Network (GSN). PKIKP precursors were first observed by Gutenberg and Richter [2], which precede PKIKP by as much as 18 s and increase gradually in amplitude with time. There were numerous hypotheses for the origin of the precursors [3−6]. A widely-accepted view about PKIKP precursors was first proposed by Haddon [7] in 1972-PKIKP precursors are caused not by radial structures of the earth but rather result from the scatterers inside the D'' region (the bottom a few hundred kilometers of the mantle) or from short-scale topography of the core-mantle-boundary (CMB). This viewpoint was further documented in detail by Cleary and Haddon [8].The results with higher precision from seismic array analyses have also suggested that the precursors are scattered waves from the lower mantle [9 − 12], because observed arrival times, amplitudes, incident angles and arrival azimuths can be well explained by scattering theory. In general, a scattered wave traverses a longer path than a direct wave does, and consequently it arrives after the direct wave. Haddon [7] showed that PKIKP precursors are able to precede the reference phase because of the distorted ray geometries resulting from the scatterers in the lower mantle. Global simulations with single and multiple scatterers distributed in the mantle have improved our understanding of PKIKP precursors [13 − 15]. PKIKP precursors provide a unique time window to study the scatterers in the mantle because they arrive before any other seismic phases and are not contaminated by direct waves or resonances. Numerous PKIKP precursors were observed in the high signal-to-noise ratio data recorded by global and local seismic networks, large and small aperture seismic arrays [1,16,17].Despite a large amount of observations on the PKIKP

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“…semblance analysis and frequency–wavenumber ( f–k ) analysis] quantitatively estimated the distribution of small‐scale heterogeneities from coherent arrivals in coda (e.g. Capon 1969; Neidell & Taner 1971; Nikolaev & Troitskiy 1987; Gupta et al 1990). Using the f–k analysis, Gupta et al (1990) analysed seismograms at the EKA and NORESS arrays using a nuclear explosion as a seismic source and determined locations of several distinct scatterers.…”

Section: Introductionmentioning

confidence: 99%

“…Capon 1969; Neidell & Taner 1971; Nikolaev & Troitskiy 1987; Gupta et al 1990). Using the f–k analysis, Gupta et al (1990) analysed seismograms at the EKA and NORESS arrays using a nuclear explosion as a seismic source and determined locations of several distinct scatterers. Matsumoto et al (1998) applied the slant stack method to the data of a small‐aperture seismic array in the source region of the 1995 Hyogo‐ken Nanbu earthquake (M7.2) and showed strong scatterers concentrated just beneath the hypocentre.…”

Section: Introductionmentioning

confidence: 99%

Imaging of three-dimensional small-scale heterogeneities in the Hidaka, Japan region: coda spectral analysis

Taira

Yomogida

2004

Geophysical Journal International

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S U M M A R YWhile large-scale heterogeneities have been studied intensively by seismic tomography with traveltime data, small-scale heterogeneities are not fully investigated yet. We obtained the 3-D spatial distribution of small-scale heterogeneities as relative scattering coefficients in the Hidaka, Japan, region using the spatial variation of high-frequency coda power spectra. We analysed 530 seismograms recorded at 62 stations for nine local earthquakes in the frequency range of 1-32 Hz. After correcting source, station and propagation effects, we assigned the spatial and temporal variations of observed power spectra of coda waves into the 3-D distribution of scattering coefficient, based on single and isotropic scattering models. Small-scale heterogeneities are distributed not only in a non-uniform manner but also differently among scale lengths estimated from their frequency dependence. An area of large relative scattering coefficient in 2 and 16 Hz is located at a depth shallower than 45 km in the southwest of the Hidaka Mountains, correlating well with a highly active area of microearthquakes. At a depth of 60-120 km, two dipping zones of large scattering coefficient are imaged beneath the summit of the Hidaka Mountains. These zones may imply two layers of strong seismic-wave reflection, consistent with the upper and lower planes of the double seismic zone in the subducting Pacific Plate, as determined by the hypocentral distribution in this region.

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Broadband F‐k analysis of array data to identify sources of local scattering

Cited by 32 publications

References 3 publications

Array analysis of the large-aperture array of the 1988-89 PASSCAL Basin and Range Passive-Source Seismic Experiment

Array analysis of the large-aperture array of the 1988-89 PASSCAL Basin and Range Passive-Source Seismic Experiment

Locating seismic scatterers at the base of the mantle beneath eastern Tibet with PKIKP precursors

Imaging of three-dimensional small-scale heterogeneities in the Hidaka, Japan region: coda spectral analysis

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