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Title: Variation of seismic coda wave attenuation in the Garhwal region, northwestern Himalaya
Authors: Tripathi J.N.
Singh P.
Sharma M.L.
Published in: Pure and Applied Geophysics
Abstract: Seismic coda wave attenuation (Q c -1) characteristics in the Garhwal region, northwestern Himalaya is studied using 113 short-period, vertical component seismic observations from local events with hypocentral distance less than 250 km and magnitude range between 1.0 to 4.0. They are located mainly in the vicinity of the Main Boundary Thrust (MBT) and the Main Central Thrust (MCT), which are well-defined tectonic discontinuities in the Himalayas. Coda wave attenuation (Q c -1) is estimated using the single isotropic scattering method at central frequencies 1.5, 3, 5, 7, 9, 12, 16, 20, 24 and 28 Hz using several starting lapse times and coda window lengths for the analysis. Results show that the (Q c -1) values are frequency dependent in the considered frequency range, and they fit the frequency power law (Q c -1 (f) = Q o -1f -n). The Q 0 (Q c at 1 Hz) estimates vary from about 50 for a 10 s lapse time and 10 s window length, to about 350 for a 60 s lapse time and 60 s window length combination. The exponent of the frequency dependence law, n ranges from 1.2 to 0.7; however, it is greater than 0.8, in general, which correlates well with the values obtained in other seismically and tectonically active and highly heterogeneous regions. The attenuation in the Garhwal region is found to be lower than the Q c -1 values obtained for other seismically active regions of the world; however, it is comparable to other regions of India. The spatial variation of coda attenuation indicates that the level of heterogeneity decreases with increasing depth. The variation of coda attenuation has been estimated for different lapse time and window length combinations to observe the effect with depth and it indicates that the upper lithosphere is more active seismically as compared to the lower lithosphere and the heterogeneity decreases with increasing depth. © 2011 Springer Basel AG.
Citation: Pure and Applied Geophysics (2012), 169(43862): 71-88
Issue Date: 2012
Keywords: Attenuation
Coda Wave
Garhwal Himalayas
Lapse Time
ISSN: 334553
Author Scopus IDs: 7003845661
Author Affiliations: Tripathi, J.N., Department of Earth and Planetary Sciences, University of Allahabad, Allahabad 211002, India
Singh, P., Department of Earth and Planetary Sciences, University of Allahabad, Allahabad 211002, India
Sharma, M.L., Department of Earthquake Engineering, Indian Institute of Technology, Roorkee 247667, India
Funding Details: The authors thank the editor of PAGEOPH, and two anonymous reviewers for their valuable comments and suggestions which helped in improving manuscript. One of the authors (JNT) is very much thankful to Prof. Haruo Sato for valuable discussion on coda waves. Authors are also thankful to Mr. Shakeel Asharaf for his help in preparation of Fig. 1. The data used for the study was acquired under the research project funded to MLS by Department of Science and Technology (DST), New Delhi. Thus, the financial grant by DST is thankfully acknowledged.
Corresponding Author: Tripathi, J. N.; Department of Earth and Planetary Sciences, University of Allahabad, Allahabad 211002, India; email:
Appears in Collections:Journal Publications [EQ]

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