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| Titel |
An Study of S-wave Attenuation using records from the 20 May, 2012 Emilia Earthquake, Italy and the Main Aftershocks |
| VerfasserIn |
Raul Castro, Francesca Pacor, Rodolfo Puglia, Gabriele Ameri, Jean Letort, Marco Massa, Lucia Luzi, Paolo Augliera |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074802
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| Zusammenfassung |
| We analyze the S-wave spectral amplitude decay with distance using strong-motion records
from the 20 May 2012 Emilia-Romagna earthquake (Mw6.1) and five aftershocks with
magnitudes ranging between 4.9 and 5.9. The data set consist of 6 earthquakes, 44 stations
and 248 records with hypocentral distances in the range 10 < r < 100 km. We rotated
the accelerograms to calculate transversal and radial components of the acceleration
spectrum. We found nonparametric attenuation functions that describe the spectral amplitude
decay of SH and SV waves with distance at 60 different frequencies between 0.1
and 40 Hz. These attenuation functions provide an estimate of the quality factor
Q at each frequency analyzed. Assuming that geometrical spreading is 1-r for
r -¤ rx and 1/(rxr)0.5 for r>rx with rx= 60 km and normalizing at 15 km
(the recording distance where the attenuation functions start to decay), we find
that the average Q for SH waves can be approximated by QSH = 82f1.2 and by
QSV = 79f1.2 for SV waves in the frequency range 0.10 -¤ f -¤ 10.7 Hz. At higher
frequencies, 11.8 -¤ f -¤ 40 Hz, the frequency dependence of Q weakens and is
approximated by QSH = 301f0.36 and QSV = 384f0.28. These results indicate that
the S-wave attenuation is isotropic at local distances in the epicenter area. The
estimates of total Q obtained (intrinsic and scattering attenuation) coincide with
the estimates of total Q determined by Del Pezzo et al. (2011) in north central
Italy using coda waves and Multiple Lapse Time Window Analysis (MLTWA). |
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