The attenuation mechanism of seismic waves in northwestern Himalayas |
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Authors: | S. Mukhopadhyay C. Tyagi S. S. Rai |
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Affiliation: | Department of Earth Sciences, IIT Roorkee, Roorkee-247667,;Uttaranchal, India. E-mail: National Geophysical Research Institute, Uppal Road, Hyderabad, India |
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Abstract: | We analysed local earthquake waveforms recorded on a broad-band seismic network in northwestern Himalayas to compute the intrinsic and scattered attenuation parameters from coda waves. Similar to other tectonically active and heterogeneous regions, attenuation-frequency relation for western Himalaya is Q −1 c = (113 ± 7) f (1.01±0.05) where Qc is the coda Q parameter. Intrinsic ( Q −1 i ) and scattering ( Q −1 s ) attenuations was separated using Qc and direct S -wave Q data ( Qd ) . It is observed that estimated Q −1 c is close to Q −1 i and both of them are much larger than Q −1 s suggesting that coda decay is predominantly caused by intrinsic attenuation. At higher frequencies, both the attenuation parameters Qc and, Qd are similar indicating that coda is predominantly composed of back-scattered S waves at these frequencies. |
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Keywords: | coda Q direct S-wave Q intrinsic attenuation northwestern Himalayas scattering attenuation |
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