کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4742568 | 1641597 | 2006 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Separation of Qi and Qs from passive data at Mt. Vesuvius: A reappraisal of the seismic attenuation estimates
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فیزیک زمین (ژئو فیزیک)
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Separation of Qi and Qs from passive data at Mt. Vesuvius: A reappraisal of the seismic attenuation estimates Separation of Qi and Qs from passive data at Mt. Vesuvius: A reappraisal of the seismic attenuation estimates](/preview/png/4742568.png)
چکیده انگلیسی
Seismic attenuation in the area of Mt. Vesuvius is reappraised by studying more than 400 S-coda envelopes of small local VT earthquakes recorded at Mt. Vesuvius from 1996 to 2002 at the three-component stations of OVO and BKE. The purpose is to obtain a stable separate estimate of intrinsic and scattering quality factors for shear waves. We investigate in the present paper four frequency bands, centered respectively at fc = 3, 6, 12 and 18 Hz with a bandwidth of 0.6fc. Stacked coda envelopes are fit to the multiple scattering model according to the Zeng approximation in the hypothesis of constant velocity half space. Results show that the diffusion regime is a good approximation as the scattering attenuation (proportional to QSâ1, the inverse scattering-quality factor) is much stronger than the intrinsic dissipation (proportional to QIâ1). QSâ1 decreases with frequency while intrinsic attenuation is much less frequency-dependent. We also fit the stacked coda envelopes at BKE to the diffusion equation solved with the boundary condition of a 2 km thick diffusive layer over a homogeneous half space. Results show that the diffusivity, D, estimated in the assumption of reflecting boundary condition is greater than that estimated in the assumption of uniform half space, whereas the diffusivity estimated with the absorbing boundary condition is close to the estimate done in the assumption of half space. OVO station shows results different from those obtained at BKE and at a group of five stations located on Mt. Vesuvius for the frequency bands centered at 12 and 18 Hz. In these two bands, scattering attenuation at OVO is comparable to the intrinsic dissipation, and is much smaller than that measured at the other stations. We interpret this anomaly as due to an effect of strong lateral heterogeneity which modifies the redistribution of the seismic energy into the coda at OVO. A comparison of the results obtained using passive data (the present data set) and the active data obtained in the same area during TOMOVES experiment by Wegler (2004) show that the diffusivity estimated with shot data during TOMOVES is smaller of a factor greater than 4. This discrepancy is interpreted as due to different earth volumes sampled by the coda waves in the two cases.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physics of the Earth and Planetary Interiors - Volume 159, Issues 3â4, December 2006, Pages 202-212
Journal: Physics of the Earth and Planetary Interiors - Volume 159, Issues 3â4, December 2006, Pages 202-212
نویسندگان
Edoardo Del Pezzo, Francesca Bianco, Lucia Zaccarelli,