Sedimentary Basins and the Blockage of Lg Wave Propagation in the Continents

2001 ◽  
pp. 1207-1250
Author(s):  
Douglas R. Baumgardt
Keyword(s):  
Wave Propagation ◽  
Sedimentary Basins ◽  
Lg Wave

scholarly journals Lg wave propagation in the area around Japan: observations and simulations

2014 ◽  
Vol 1 (1) ◽  
pp. 10 ◽  
Author(s):  
Takashi Furumura ◽  
Tae-Kyung Hong ◽  
Brian LN Kennett
Keyword(s):  
Wave Propagation ◽  
Lg Wave

Lg wave propagation and attenuation characteristics of the NW Himalaya

2021 ◽  
Author(s):  
Kaushik Kumar Pradhan ◽  
Supriyo Mitra
Keyword(s):  
Wave Propagation ◽  
Quality Factor ◽  
Spectral Ratio ◽  
Spectral Amplitude ◽  
Nw Himalaya ◽  
Jammu And Kashmir ◽  
Waveform Data ◽  
Ground Shaking ◽  
Lg Wave ◽  
Attenuation Characteristics

<p>Lg waves are formed by the superposition of shear waves trapped within the crustal waveguide and are the most destructive at regional distances. Excitation of Lg waves, its propagation and lateral variability determine the intensity of ground shaking from regional earthquakes. Spatial decay of spectral amplitude of Lg waves have been used to quantify the attenuation characteristics of the crust. In this study we use regional waveform data from the Jammu and Kashmir Seismological NETwork (JAKSNET) to study Lg wave propagation across the Indian Peninsula, Himalaya, Tibetan Plateau and Hindu Kush regions. We compute Lg/Sn wave ratio to distinguish regions with efficient Lg propagation from those with Lg blockage. These results are categorised using earthquake magnitude and depth to study Lg wave excitation and propagation across these varying geological terrains. We further use the two-station method to study Lg wave quality factor and its frequency dependence for the NW Himalaya. Seismograms recorded at two stations of the network, which are aligned within 15 degrees of the event, are used for analysis. The spectral ratio of Lg wave amplitude recorded at the two stations will be used to estimate the Q (quality factor) as a function of frequency. This will provide Q<sub>0</sub> along all inter-station paths, which will then be combined to form Q<sub>0</sub> tomography maps for the region. Checkerboard tests will be performed to estimate the resolution of the tomographic maps and accordingly the results will be interpreted.</p>

Study of Surface Effects on LG Wave Propagation in Heterogeneous Crusts by a GS-BE Hybrid Method

1998 ◽  
Author(s):  
R. S. Wu ◽  
T. Lay ◽  
X. B. Xie ◽  
L. Fu ◽  
S. Jin
Keyword(s):  
Wave Propagation ◽  
Hybrid Method ◽  
Surface Effects ◽  
Lg Wave

Numerical simulations of wave propagation in heterogeneous wave guides with implications for regional wave propagation and the nature of lithospheric heterogeneity

1996 ◽  
Vol 86 (4) ◽  
pp. 1200-1206
Author(s):  
Gregory S. Wagner
Keyword(s):  
Wave Propagation ◽  
Scattered Wave ◽  
Wave Guide ◽  
Subsurface Structure ◽  
Forward Scatter ◽  
Wave Fields ◽  
Wave Guides ◽  
Statistical Sense ◽  
Lg Wave ◽  
Wave Trains

Abstract I present results from elastic finite-difference simulations of regional wave propagation conducted in an effort to characterize, in a statistical sense, the nature of lithospheric heterogeneities required to generate scattered wave fields with characteristics consistent with those observed in regional array data. In particular, regional P, S, and Lg wave trains that are comprised not of the occasional coherent deterministic phase emersed in randomly scattered coda, but of a continuous succession of coherent forward-scattered arrivals. My modeling suggests that lithospheric heterogeneities should be parameterized using spatially anisotropic correlation functions. Models containing spatially isotropic heterogeneities inhibit the extent to which energy is forward scattered and trapped in the crustal wave guide and, consequently, produce regional wave fields whose characteristics are inconsistent with array observations. Models containing spatially anisotropic heterogeneities—which preferentially forward scatter energy that is subsequently trapped in the crustal wave guide—produce wave fields whose characteristics are consistent with regional array observations and provide intuitively appealing representations of subsurface structure.

Lg Wave Propagation in Eurasia

1981 ◽  
pp. 421-451 ◽  
Author(s):  
Svein Mykkeltveit ◽  
Eystein S. Husebye
Keyword(s):  
Wave Propagation ◽  
Lg Wave

Love-wave propagation in a three-dimensional sedimentary basin

1992 ◽  
Vol 82 (4) ◽  
pp. 1661-1677 ◽  
Author(s):  
Takumi Toshinawa ◽  
Tatsuo Ohmachi
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Love Wave ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Sedimentary Basins ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Time Histories

Abstract A simplified three-dimensional finite-element method has been developed for simulation of Love-wave propagation in three-dimensional sedimentary basins. The eigenfunctions for the fundamental-mode surface waves are employed as interpolation functions in the finite-element scheme. By reducing the number of degrees of freedom, the method enables us to analyze wave propagation in an area of 2000 km2 as large as the southern part of the Kanto plain, Japan. Time histories of the near Izu-Ohshima earthquake of 1990 are calculated and compared with observation. Calculated displacement snapshots show the effect of three-dimensional topography on direction of Love-wave propagation. The three-dimensional simulation is also compared with a two-dimensional one, demonstrating amplitude increase and extended duration. Time histories and their spectra from the three-dimensional model show better agreement with the observations than those from the two-dimensional model.

Laboratory results for the features of body‐wave propagation in a transversely isotropic media

Geophysics ◽  
2001 ◽  
Vol 66 (6) ◽  
pp. 1921-1924 ◽  
Author(s):  
Young‐Fo Chang ◽  
Chih‐Hsiung Chang
Keyword(s):  
Wave Propagation ◽  
Shear Wave ◽  
Elastic Anisotropy ◽  
Body Wave ◽  
Transversely Isotropic ◽  
Sedimentary Basins ◽  
Seismic Profiles ◽  
Vertical Seismic Profiles ◽  
Transversely Isotropic Media ◽  
Isotropic Media

Much of the earth’s crust appears to have some degree of elastic anisotropy (Crampin, 1981; Crampin and Lovell, 1991; Helbig, 1993). The phenomena of elastic wave propagation in anisotropic media are more complex than those in isotropic media. Shear‐wave propagation in an orthorhombic physical model is most complex when the direction of the wave is close to the neighborhood of the cusp on the group velocity surfaces (Brown et al., 1991). The first identification of singularities in wave propagation through sedimentary basins occurred in the examination of shear‐wave splitting in multioffset vertical seismic profiles (VSPs) at a borehole site in the Paris Basin (Bush and Crampin, 1991), where large variations in shear‐wave polarizations in propagation directions close to point singularities were observed. Computation of synthetic seismograms for layer sequences showed that the shear‐wave polarizations and amplitudes were irregular near point singularities (Crampin, 1991).

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