A direct method for extracting surface waves of green’s functions in a multilayered medium

2008 ◽  
Author(s):  
Daoxiang Wang ◽  
Kai-Ning Edward Yung ◽  
Jian Bao ◽  
Rushan Chen
Keyword(s):  
Surface Waves ◽  
Green's Functions ◽  
Green’S Functions ◽  
Direct Method ◽  
Multilayered Medium ◽  
A Direct Method

scholarly journals Asymptotic analysis for dispersion relations and travel times in noise cross-correlations: spherically symmetric case

2018 ◽  
Vol 474 (2218) ◽  
pp. 20180382
Author(s):  
Tianshi Liu ◽  
Haiming Zhang
Keyword(s):  
Asymptotic Analysis ◽  
Surface Waves ◽  
Green's Functions ◽  
Green’S Functions ◽  
Dispersion Relations ◽  
Body Waves ◽  
Spherically Symmetric ◽  
Travel Times ◽  
Cross Correlations ◽  
The Cross

The cross-correlations of ambient noise or earthquake codas are massively used in seismic tomography to measure the dispersion curves of surface waves and the travel times of body waves. Such measurements are based on the assumption that these kinematic parameters in the cross-correlations of noise coincide with those in Green's functions. However, the relation between the cross-correlations of noise and Green's functions deserves to be studied more precisely. In this paper, we use the asymptotic analysis to study the dispersion relations of surface waves and the travel times of body waves, and come to the conclusion that for the spherically symmetric Earth model, when the distribution of noise sources is laterally uniform, the dispersion relations of surface waves and the travel times of SH body-wave phases in noise correlations should be exactly the same as those in Green's functions.

scholarly journals Source characteristics of the 17 January 1994 Northridge, California, earthquake from regional broadband modeling

1995 ◽  
Vol 85 (6) ◽  
pp. 1591-1603 ◽  
Author(s):  
Xi J. Song ◽  
Laura E. Jones ◽  
Donald V. Helmberger
Keyword(s):  
Surface Waves ◽  
Green's Functions ◽  
Green’S Functions ◽  
Estimation Algorithm ◽  
Source Mechanism ◽  
Northridge Earthquake ◽  
Rupture Directivity ◽  
Field Source ◽  
Source Characteristics ◽  
The North

Abstract Broadband regional records are modeled to determine source mechanism, seismic moment, fault dimension, and rupture directivity for the 17 January 1994 Northridge earthquake. Modeling is done using both theoretical Green's functions (tGf) and empirical Green's functions (eGf). From the theoretical modeling, we obtain a source mechanism with strike 128°, dip 33°, and rake 106° for the mainshock, using a source estimation algorithm by Zhao and Helmberger (1994). While the fault orientation seems resolvable from regional data, the moment estimation is less reliable due to inadequate synthetic waveform fits to the observed surface waves. This appears to be caused by the combination of propagational effects and fault complexities. Further investigation of the source characteristics is carried out with a new method of using eGf's. As an eGf, we select the 17 January 1994 17:56 GMT aftershock, which occurred near the onset of the mainshock and had a similar source mechanism. The source duration of the mainshock, as seen from the regional surface waves observed at various stations, is obtained by searching for the trapezodial far-field source-time function for each station that, when convolved with the aftershock data, best simulates the mainshock data. Stations to the north record shorter source durations than stations to the south. Modeling these with theoretical predictions of rupture on a square fault, we constrain the effective fault dimension to be 14 km with rupture along the direction of the average rake vector. A moment of (1.4 ± 0.9) × 1026 dyne-cm with a stress drop of ∼120 bars is obtained for the mainshock from our eGf study.

A New Method for Locating the Poles of Green's Functions in a Lossless or Lossy Multilayered Medium

2010 ◽  
Vol 58 (7) ◽  
pp. 2295-2300 ◽  
Author(s):  
Dao-Xiang Wang ◽  
Edward Kai-Ning Yung ◽  
Ru-Shan Chen ◽  
Jian Bao
Keyword(s):  
Green's Functions ◽  
Green’S Functions ◽  
New Method ◽  
Multilayered Medium
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