Erratum to Rayleigh‐Wave H/V via Noise Cross Correlation in Southern California

2019 ◽  
Vol 109 (5) ◽  
pp. 2140-2141
Author(s):  
Jack B. Muir ◽  
Victor C. Tsai
Keyword(s):  
Rayleigh Wave ◽  
Southern California ◽  
Cross Correlation ◽  
Noise Cross Correlation

scholarly journals Ambient noise cross-correlation observations of fundamental and higher-mode Rayleigh wave propagation governed by basement resonance

2021 ◽  
Author(s):  
Martha Savage ◽  
FC Lin ◽  
John Townend
Keyword(s):  
Rayleigh Wave ◽  
Correlation Functions ◽  
Rayleigh Waves ◽  
Ambient Noise ◽  
Cross Correlation ◽  
Amplitude Ratio ◽  
Sedimentary Basins ◽  
Longitudinal Motion ◽  
Resonance Frequencies ◽  
Noise Cross Correlation

Measurement of basement seismic resonance frequencies can elucidate shallow velocity structure, an important factor in earthquake hazard estimation. Ambient noise cross correlation, which is well-suited to studying shallow earth structure, is commonly used to analyze fundamental-mode Rayleigh waves and, increasingly, Love waves. Here we show via multicomponent ambient noise cross correlation that the basement resonance frequency in the Canterbury region of New Zealand can be straightforwardly determined based on the horizontal to vertical amplitude ratio (H/V ratio) of the first higher-mode Rayleigh waves. At periods of 1-3 s, the first higher-mode is evident on the radial-radial cross-correlation functions but almost absent in the vertical-vertical cross-correlation functions, implying longitudinal motion and a high H/V ratio. A one-dimensional regional velocity model incorporating a ~ 1.5 km-thick sedimentary layer fits both the observed H/V ratio and Rayleigh wave group velocity. Similar analysis may enable resonance characteristics of other sedimentary basins to be determined. © 2013. American Geophysical Union. All Rights Reserved.

scholarly journals On seismic ambient noise cross-correlation and surface-wave attenuation

2019 ◽  
Vol 219 (3) ◽  
pp. 1568-1589
Author(s):  
Lapo Boschi ◽  
Fabrizio Magrini ◽  
Fabio Cammarano ◽  
Mark van der Meijde
Keyword(s):  
Rayleigh Wave ◽  
Ambient Noise ◽  
Cross Correlation ◽  
Wave Attenuation ◽  
Mathematical Expression ◽  
Seismic Ambient Noise ◽  
Multiplicative Factor ◽  
Cross Correlations ◽  
Noise Cross Correlation ◽  
Preliminary Application

SUMMARY We derive a theoretical relationship between the cross correlation of ambient Rayleigh waves (seismic ambient noise) and the attenuation parameter α associated with Rayleigh-wave propagation. In particular, we derive a mathematical expression for the multiplicative factor relating normalized cross correlation to the Rayleigh-wave Green’s function. Based on this expression, we formulate an inverse problem to determine α from cross correlations of recorded ambient signal. We conduct a preliminary application of our algorithm to a relatively small instrument array, conveniently deployed on an island. In our setup, the mentioned multiplicative factor has values of about 2.5–3, which, if neglected, could result in a significant underestimate of α. We find that our inferred values of α are reasonable, in comparison with independently obtained estimates found in the literature. Allowing α to vary with respect to frequency results in a reduction of misfit between observed and predicted cross correlations.

scholarly journals Ambient noise cross-correlation observations of fundamental and higher-mode Rayleigh wave propagation governed by basement resonance

2021 ◽  
Author(s):  
Martha Savage ◽  
FC Lin ◽  
John Townend
Keyword(s):  
Rayleigh Wave ◽  
Correlation Functions ◽  
Rayleigh Waves ◽  
Ambient Noise ◽  
Cross Correlation ◽  
Amplitude Ratio ◽  
Sedimentary Basins ◽  
Longitudinal Motion ◽  
Resonance Frequencies ◽  
Noise Cross Correlation

Measurement of basement seismic resonance frequencies can elucidate shallow velocity structure, an important factor in earthquake hazard estimation. Ambient noise cross correlation, which is well-suited to studying shallow earth structure, is commonly used to analyze fundamental-mode Rayleigh waves and, increasingly, Love waves. Here we show via multicomponent ambient noise cross correlation that the basement resonance frequency in the Canterbury region of New Zealand can be straightforwardly determined based on the horizontal to vertical amplitude ratio (H/V ratio) of the first higher-mode Rayleigh waves. At periods of 1-3 s, the first higher-mode is evident on the radial-radial cross-correlation functions but almost absent in the vertical-vertical cross-correlation functions, implying longitudinal motion and a high H/V ratio. A one-dimensional regional velocity model incorporating a ~ 1.5 km-thick sedimentary layer fits both the observed H/V ratio and Rayleigh wave group velocity. Similar analysis may enable resonance characteristics of other sedimentary basins to be determined. © 2013. American Geophysical Union. All Rights Reserved.

The azimuthal dependence of Rayleigh wave ellipticity in a slightly anisotropic medium

2021 ◽  
Author(s):  
Shaoqian Hu ◽  
Huajian Yao ◽  
Hsin-Ying Yang
Keyword(s):  
Phase Velocity ◽  
Rayleigh Wave ◽  
Anisotropic Medium ◽  
Cross Correlation ◽  
Real Data ◽  
Azimuthal Dependence ◽  
Propagator Matrix ◽  
Theoretical Investigations ◽  
Transverse Isotropic ◽  
Noise Cross Correlation

Summary A recent study analyzed the Rayleigh wave ellipticity obtained by ambient noise cross-correlation in periods of 8∼20 s, and observed the Rayleigh wave ellipticity is backazimuth-dependent with a 180○ periodicity in the contiguous United States. However, the azimuthal anisotropic parameters have not been inverted to depths, and the comparison with other seismic results has not been possible so far, partially due to the lack of related theoretical investigations. Here we first derive explicit formulation to relate the period-dependent backazimuthal Rayleigh wave ellipticity with the depth-dependent azimuthal wavespeed variation in a slightly anisotropic medium based on the variational principle; by carefully examining relations among different parameterizations of a horizontally transverse isotropic medium, we then express the final formulation in terms of Crampin’s notation. The formulation is verified by comparison with the results of anisotropic propagator matrix technique. Tests show the backazimuth-dependent Rayleigh wave ellipticity provides complementary information on anisotropic parameters in addition to the widely used phase velocity. A simple application of the derived formulation to real data in North America is also provided. Our formulation can be regarded as an extension of the classic work on azimuthal-dependent phase velocity, and helps to quantitatively explain the backazimuth-dependent Rayleigh wave ellipticity.

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