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| Titel |
Ellipticity of Rayleigh waves and crustal structure in northern Italy |
| VerfasserIn |
Andrea Berbellini, Andrea Morelli, Ana M. G. Ferreira |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250133628
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| Publikation (Nr.) |
 EGU/EGU2016-14261.pdf |
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| Zusammenfassung |
| Horizontal-to-vertical amplitude ratio of elliptically-polarised ground motion of
Rayleigh waves depends on the local crustal structure. Its measurement therefore adds
another, seldom used, tool to image shallow earth structure. Frequency-dependent
sensitivity kernels are dominated by shear-wave velocity and are rather shallow, so they
are a convenient tool to model sedimentary layers that nicely complement surface
wave studies. We perform extensive measurements, in the period range between 10
and 110 s, on traces from about 500 globally-distributed earthquakes, occurred in
years 2008 ÷ 2014, recorded by 95 stations in northern Italy —- a region including
the wide basin of the Po Plain and encircling Alps and northern Apennines. The
observations are well correlated with known strucure: high ellipticity correlates well with
low seismic velocity (such as in the Po Plain), and low ellipticity corresponds to
fast seismic velocity in hard rock environments in correspondence of Alps and
Apennines. Comparison between observations and predicted ellipticity from a reference
crustal model of the region (Molinari et al., 2015) shows substantial fit. Sensitivity
to vS is quite non linear, but inversion is possible and may provide very useful
complementary information to, e.g., surface wave phase or group velocity or receiver
functions. |
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