Publication Date:
2017-04-04
Description:
Local and regional seismicity jointly recorded by two dense small aperture arrays, one installed at surface and one at 1.3 km depth, constitutes an interesting data set useful for coda observations. Applying array techniques to earthquakes recorded at the two arrays we measure slowness, backazimuth and correlation coefficient of the coherent coda wave signals in five frequency bands in the range 1–10 Hz. Slowness distributions show marked differences between surface and underground, with slow signals at surface (slowness greater than 1.0 s km−1) that
are not observed underground. We interpret these coherent signals as surface waves produced by the interaction of body waves with the free surface characterized by rough topography.
The backazimuth values measured in the frequency bands centred at 1.5 and 3 Hz are almost uniformly distributed between 0 and 360◦, while those measured at higher frequencies show different distributions between surface and underground. On the contrary, the earthquake envelopes
show very similar coda shapes between surface and underground recordings, with an
almost constant coda-amplitude ratio (between 4 and 8) in a wide frequency range.
Description:
Published
Description:
367-371
Description:
1.1. TTC - Monitoraggio sismico del territorio nazionale
Description:
JCR Journal
Description:
restricted
Keywords:
Coda waves
;
Wave scattering and diffraction
;
Wave propagation
;
04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
