Earth-prints repository, logo   DSpace

About DSpace Software
|earth-prints home page | roma library | bologna library | catania library | milano library | napoli library | palermo library
Please use this identifier to cite or link to this item:

Authors: Pischiutta, Marta*
Rovelli, Antonio*
Fle, Jon B.*
Salvini, Francesco*
Ben-Zion, Yehuda*
Editors: Pischiutta, Marta; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia
Issue Date: 13-Dec-2010
Keywords: site effects
Abstract: Several recent studies indicate that ambient noise and seismic signals in fault zones tend to be polarized on the horizontal plane with a clear preferred orientation direction. Here we present a summary of past experiments as well as new study cases showing evidence of this effect: the Val d’Agri, the Pernicana and the Paganica faults in Italy, and the Hayward fault in California. We also analyze data recorded by the HRSN network at the Parkfield section of the San Andreas fault and find that stations MM and GH that are close to the fault damage zone show a similar persistent and marked polarization effect. The approach combines the H/V technique in the frequency domain with the covariance matrix diagonalization method in the time domain. Common features are: i) a high stability of results at each site, independently of the nature and location of the source of seismic signals, ii) a characteristic polarization for each fault, and iii) the preferred polarization is close to the fault-normal direction, rather than being fault parallel as would be expected for generation of fault zone trapped waves. In previous papers, the role of fluid-filled microcracks in the damage zone was hypothesized. We have then explored an hypothesis based on the fracture field orientation in the fault damage zone by applying the package FRAP3 (Salvini, 2002) to model the brittle deformation field expected for the studied faults. We have found a consistent orthogonal relation between the observed polarizations and the orientation of the predicted synthetic fracture systems. When anisotropy studies are available, the horizontal ground motion polarization is consistently found to be perpendicular to the fast wave splitting component. The results may reflect reduced stiffness in the fault-normal direction produced by the presence of damage fault zone rocks.
Appears in Collections:Conference materials
04.06.04. Ground motion

Files in This Item:

File SizeFormatVisibility
agu 2010.pdf485.91 kBAdobe PDFView/Open

This item is licensed under a Creative Commons License
Creative Commons

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Share this record




Stumble it!



Valid XHTML 1.0! ICT Support, development & maintenance are provided by CINECA. Powered on DSpace Software. CINECA