Is the Single Scattering Model Invalid for the Coda Excitation at Long Lapse Time?

1988 ◽  
pp. 43-47
Author(s):  
Haruo Sato
Keyword(s):  
Single Scattering ◽  
Lapse Time ◽  
Scattering Model

Laser Doppler measurement of retinal blood velocity: validity of the single scattering model

1985 ◽  
Vol 24 (5) ◽  
pp. 605 ◽  
Author(s):  
Charles E. Riva ◽  
Juan E. Grunwald ◽  
Benno L. Petrig
Keyword(s):  
Single Scattering ◽  
Blood Velocity ◽  
Laser Doppler ◽  
Doppler Measurement ◽  
Scattering Model

Experimental and theoretical low-energy photoelectron diffraction study of the W(001) surface: Adequacy of a single scattering model

1987 ◽  
Vol 185 (3) ◽  
pp. L527-L533 ◽  
Author(s):  
D. Sebilleau ◽  
M.C. Desjonqueres ◽  
D. Chauveau ◽  
C. Guillot ◽  
J. Lecante ◽  
...  
Keyword(s):  
Diffraction Study ◽  
Single Scattering ◽  
Low Energy ◽  
Scattering Model ◽  
Photoelectron Diffraction

A practical analytic single scattering model for real time rendering

2005 ◽  
Vol 24 (3) ◽  
pp. 1040-1049 ◽  
Author(s):  
Bo Sun ◽  
Ravi Ramamoorthi ◽  
Srinivasa G. Narasimhan ◽  
Shree K. Nayar
Keyword(s):  
Real Time ◽  
Single Scattering ◽  
Scattering Model

Seismic attenuation tomography of the North-Western Himalaya using Coda waves

2020 ◽  
Author(s):  
Amit Bera ◽  
Himanshu Agrawal ◽  
Supriyo Mitra ◽  
Shubham Sharma
Keyword(s):  
Quality Factor ◽  
Western Himalaya ◽  
Coda Waves ◽  
Projection Algorithm ◽  
Lapse Time ◽  
Scattering Model ◽  
The North ◽  
Temporal Decay ◽  
Back Scattering ◽  
Least Squares Approach

<p>We use 4695 local waveforms from 1206 earthquakes (epicentral distance < 350 km and 2.0 ≤ Mw ≤ 5.5) recorded by IISER Kolkata network (IK) at 22 stations (32°N to 35°N latitude and 74°E to 77°E longitude), located within the North-Western Himalaya (28°N to 39°N latitude and 68°E to 81°E longitude). We study the coda waves which are generally the tail of a seismogram and arrive after the main seismic waves. We use the temporal decay of coda amplitude to calculate the coda quality factor (Q<sub>c</sub>) from which we estimate the attenuation (Q<sub>c</sub><sup>-1</sup>). We consider the single back-scattering model (Aki & Chouet, 1975) where both the scattering (Q<sub>sc</sub><sup>-1</sup>) and intrinsic (Q<sub>i</sub><sup>-1</sup>) component of the attenuation are included in the measurement. We use a lapse time of 2t<sub>s</sub> (t<sub>s</sub> is the S-wave arrival time) as the starting point of the coda window. Then, we consider multiple forward-scattering model, where the attenuation (Q<sub>c</sub><sup>-1</sup>) is dominantly dependent on the intrinsic (Q<sub>i</sub><sup>-1</sup>) component. In this model we use lapse time greater than 2t<sub>s</sub> so that the coda waves encounter multiple scatterers and enter the diffusive regime. We calculate the frequency dependent quality factor for each earthquake-receiver path at frequencies 1 to 14 Hz using the linear least squares approach on temporal decay of coda amplitude. We calculate Q<sub>0</sub> (quality factor at a reference frequency f<sub>0</sub> which is chosen to be 1 Hz for the analysis) and its frequency dependence (η) using weighted least squares approach on the power law dependence of Q<sub>c </sub>on frequency. To see the lateral variation of Q in our study area, we have produced 2-D maps by combining the Q<sub>c </sub>measurements together in a tomography. For single back-scattering model we use the back-projection algorithm which is based on the calculation of area overlap of ellipses with the gridded region. For multiple forward-scattering model, the same back-projection algorithm is modified to calculate the length overlap of traces with the gridded region. To understand the spatial resolution of the 2-D Q<sub>c </sub>maps, we use the point spreading function test which quantifies the recovery of Q<sub>c </sub>perturbation. In addition to this, we also perform a standard checkerboard resolution test to ensure simultaneous recovery of Q<sub>c </sub>perturbation. We observe low Q in the Kashmir basin and Lesser Himalaya and high Q in surrounding northeastern Higher Himalaya which clearly correspond to the coda wave attenuation signatures in the older Tethyan sedimentary rocks and crystalline igneous rocks in these regions respectively.</p>

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