<scp>A technique for the analysis of transient seismic signals</scp>

Dziewoński, Adam M.; Bloch, S. C.; Landisman, Mark

doi:10.1785/bssa0590010427

Cited by 1,002 publications

(97 citation statements)

References 6 publications

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“…The data were also converted into ground motion (displacement) units using the frequency response of the recorders. Fundamental mode dispersion curves of Rayleigh wave were estimated along each path between earthquake epicenter and the seismic station using the multiple filter technique (MFT) developed by Herrmann (2013) and Herrmann and Ammon (2002) based on the methodology of Dziewonski et al (1969). MFT is a fast and efficient method used for analyzing multiple dispersed signals (Herrmann, 1973;Erduran et al, 2007).…”

Section: Estimation Of Group Velocitymentioning

confidence: 99%

Tomographic Image of Shear Wave Structure of NE India Based on Analysis of Rayleigh Wave Data

Kumar

Mukhopadhyay

et al. 2021

Front. Earth Sci.

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The major scientific purpose of this work is to evaluate the geodynamic processes involved in the development of tectonic features of NE India and its surroundings. In this work, we have obtained tomographic images of the crust and uppermost mantle using inversion of Rayleigh waveform data to augment information about the subsurface gleaned by previous works. The images obtained reveal a very complicated tectonic regime. The Bengal Basin comprises a thick layer of sediments with the thickness increasing from west to east and a sudden steepening of the basement on the eastern side of the Eocene Hinge zone. The nature of the crust below the Bengal Basin varies from oceanic in the south to continental in the north. Indo-Gangetic and Brahmaputra River Valleys comprise ∼5–6-km-thick sediments. Crustal thickness in the higher Himalayas and southern Tibet is ∼70 km but varies between ∼30 and ∼40 km in the remaining part. Several patches of low-velocity medium present in the mid-to-lower crust of southern Tibet along and across the major rifts indicate the presence of either partially molten materials or aqueous fluid. Moho depth decreases drastically from west to east across the Yadong-Gulu rift indicating the complex effect of underthrusting of the Indian plate below the Eurasian plate. Crust and upper mantle below the Shillong Massif and Mikir Hills are at a shallow level. This observation indicates that tectonic forces contribute to the uprising of the Massif.

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Section: Estimation Of Group Velocitymentioning

confidence: 99%

Tomographic Image of Shear Wave Structure of NE India Based on Analysis of Rayleigh Wave Data

Kumar

Mukhopadhyay

et al. 2021

Front. Earth Sci.

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“…The group velocity of Rayleigh waves is frequency-dependent. We measure the dispersion curves of group velocities using the multiple filter technique based on a Gaussian filter (Dziewonski et al, 1969;Herrmann, 1973). The group velocities are determined using the time lags of envelopes for filtered waveforms with peak amplitudes.…”

Section: Methodsmentioning

confidence: 99%

Ambient Noise Tomography of Upper Crustal Structures and Quaternary Faults in the Seoul Metropolitan Area and Its Geological Implications

Kil

Hong

Chung

et al. 2021

Earth and Space Science

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We investigate the upper‐crustal seismic velocity structure in the Seoul metropolitan area, where about 20 million people live. The Chugaryeong fault zone (CFZ) is placed in this area, but the seismic hazard potential remains unclear. We conducted ambient noise tomography to illuminate the high‐resolution upper‐crustal structure in the Seoul metropolitan area. We analyzed continuous vertical seismic records for ∼5 months from a dense seismic array with 77 broadband stations. Group velocity dispersion curves and tomographic maps were extracted between 0.5 and 10 s periods. We inverted 3‐D group velocity tomography models up to a depth of ∼10 km from the group velocity maps. The shear‐wave velocity model is consistent with the geological features. High‐velocity anomalies at shallow depths are correlated with the surface topography and geology. The CFZ is located at a low velocity below the 5 km depth and presented as the simplified model. The large VS contrast regions are located beneath NS‐trending faults. The cross‐sections coincide with the near‐vertical strike‐slip faults in this area. In the southern region of the Seoul metropolitan area, low‐velocity anomalies correlate with high heat flow regions. Our results effectively suggest high resolution upper‐crustal structures and subsurface hidden faults in the urban area.

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“…Based on multiple filtering techniques 62 , 63 , we manually pick the group velocity dispersion curve with Computer Programs in Seismology (CPS) software 64 . Assuming there are n stations, we can extract empirical Green’s functions on n(n-1)/2 paths.…”

Section: Methodsmentioning

confidence: 99%

Vestiges of underplating and assembly in the central North China Craton based on S-wave velocities

Tian

2021

Sci Rep

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The destruction of the North China Craton (NCC) is a controversial topic among researchers. In particular, the crustal structure associated with the craton’s destruction remains unclear, even though a large number of seismic studies have been carried out in this area. To investigate the crustal structure and its dynamic implications, we perform noise tomography in the central part of the NCC. In this study, continuous vertical-component waveforms spanning one year from 112 broadband seismic stations are used to obtain the group velocity dispersion curves of Rayleigh waves at different periods, and surface wave tomography is employed to extract the Rayleigh wave group velocity distributions at 9–40 s. Finally, the S-wave velocity structure at depths of 0–60 km is determined by the inversion of pure-path dispersion data. The results show obvious differences in the crustal structure among the Western Block (WB), the Trans-North China Orogen (TNCO) and the Eastern Block (EB). The lower crust of the northern part of the EB exhibits a high-velocity S-wave anomaly, which may be related to magmatic underplating in the lower crust induced by an upwelling mantle plume. The S-wave velocity of the WB is lower than that of the TNCO in the upper and middle crust and is lower than that of both the TNCO and the EB in the lower crust. The crust of the TNCO shows higher S-wave velocities than the WB and EB in the upper and middle crust, and its overall S-wave velocity structure is clearly different from those of the WB and EB, implying that the crustal structure of the TNCO may contain vestiges of the Paleoproterozoic collision between the WB and EB and their subsequent assembly. This study marks the first time these findings are identified for the NCC.

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A technique for the analysis of transient seismic signals

Cited by 1,002 publications

References 6 publications

Tomographic Image of Shear Wave Structure of NE India Based on Analysis of Rayleigh Wave Data

Tomographic Image of Shear Wave Structure of NE India Based on Analysis of Rayleigh Wave Data

Ambient Noise Tomography of Upper Crustal Structures and Quaternary Faults in the Seoul Metropolitan Area and Its Geological Implications

Vestiges of underplating and assembly in the central North China Craton based on S-wave velocities

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