a controlled-source experiment to investigate the origin of wavefield polarization in fault zones...
TRANSCRIPT
A controlled-source experiment to investigate the origin of wavefield polarization in fault zones
Giuseppe Di Giulio1, Antonio Rovelli2, Fabrizio Cara2, Pier Paolo Bruno3, Michele Punzo4, and Francesco Varriale5
1 Istituto Nazionale di Geofisica e Vulcanologia, L’Aquila, Italy
2 Istituto Nazionale di Geofisica e Vulcanologia, Seismology and Tectonophysics , Roma, Italy
3 Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Napoli, Italy
4 Consiglio Nazionale delle Ricerche, IAMC, Napoli, Italy
5 AMRA, Napoli, Italy
Seismotectonic setting (after Monaco et al., 2005)
White arrows represent the horizontal displacement vectors as measured by Bonforte et
al. (2008) between July 2005 and June 2006.
Faults on Mt. Etna
10 cm
10 cm
The study area: the Pernicana Fault
Rigano et al (2008) observe a strong wavefield polarization in fault zones
Ambient noise
Earthquakes
What is the origin of the strong horizontal polarization in the fault zone?
Summit crater, Mt. EtnaFalsaperla et al. 2010, JGR
At the crater stations, horizontal site polarization is independent of the source position and seismic signal nature (earthquakes, exposive volcanic episodes, tremor) and tends to be transversal to the radial fracture field
Vertical excitation, sweep modality
The controlled-source experiment
Eccitazione orizzontale e profili stazioni
A source-controlled experiment on Mt. Etna to investigate the origin of wavefield polarization in fault zones
Radial component corresponds to ''the natural site polarization''
5-Hz band-pass filter
Comp. Z
Distance 300 m
Comp. Radial
Distance 300 m
Comp. Transverse
Distance 300 m
Comp. Z
Distance 10 m
Comp. Radial
Distance 10 m
Comp. Tranverse
Distance 10 m
Array layout N240, Source Polarization N330 ''Natural Site Polarization''
Signal bp 5 Hz
Array layout N240, Source Polarization N330 ''Natural Site Polarization''
-63
m
Noise lp 2 Hz
Noise bp 5 Hz
Signal bp 5 Hz
Noise lp 2 Hz
Noise bp 5 Hz
Array layout N330, Source Polarization N240
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