Crustal Q in Southern Italy determined from regional earthquakes
| Autor: | Castro RR, Gallipoli MR, Mucciarelli M. |
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| Rok vydání: | 2008 |
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| Zdroj: | Tectonophysics (Amst. Online) 457 (2008): 96–101. info:cnr-pdr/source/autori:Castro RR, Gallipoli MR, Mucciarelli M./titolo:Crustal Q in Southern Italy determined from regional earthquakes/doi:/rivista:Tectonophysics (Amst. Online)/anno:2008/pagina_da:96/pagina_a:101/intervallo_pagine:96–101/volume:457 |
| Popis: | We estimated the quality factor Q of S waves traveling through the crust in the southern region of Italy. For that purpose 65 regional earthquakes with magnitudes ML 2.0-5.3 and hypocentral distance ranging between 7 and 375 km were analyzed. To estimate Q we first calculated a set of empirical functions that describe the S-wave spectral-amplitude decay with distance for 15 frequencies between 1 and 25 Hz. Within the distance range of the recordings, the average Q can be approximated as Q=25.7f(1.4). To separate the effect of upper and lower crust in the total Q, we used the first 50 km of the attenuation functions to estimate Q of the upper crust, and found that Q= 18.8 f(1.7). Then, using the 50-100 km segment of the attenuation functions we estimated that Q= 17.8(1.3) for the lower crust We also found that at high frequencies (f>10 Hz) the upper crust Q increases considerable relative to lower crust Q, being a factor of nine greater at 25 Hz. This higher attenuation in the lower crust may be the effect of deep structures as reported by Menardi-Noguera and Rea (2000) that were subjected to brittle-ductile deformation during past tectonic events |
| Databáze: | OpenAIRE |
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