ISSN:
1420-9136
Keywords:
Key words: Attenuation, crust, frequency dependence, high-frequency seismic waves, quality factor.
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract —Borehole seismograms from local earthquakes in the aftershock region of the 1984 western Nagano Prefecture, Japan earthquake were analyzed to measure the frequency-dependent characteristics of P- and S-wave attenuation in the upper crust. The records from a three-component velocity seismometer at the depth of 145m exhibit high S/N-ratio in a wide frequency range up to 100 Hz. Extended coda normalization methods were applied to bandpass-filtered seismograms of frequencies from 25 to 102 Hz. For the attenuation of high-frequency P and S waves, our measurements show Q P -1≃ 0.052ƒ-0.66 and Q S -1≃ 0.0034ƒ-0.12 respectively. The frequency dependence of the quality factor of S waves is very weak as compared with that of P waves. The ratio of Q P -1/Q S -1 is larger than unity in the entire analyzed frequency range.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s000240050205
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