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: http://hdl.handle.net/2122/4054

Authors: Solarino, S.*
Eva, C.*
Title: T waves in Western Mediterranean Sea after the May 21, 2003 Algerian earthquake
Issue Date: Oct-2007
Series/Report no.: 5/50 (2007)
URI: http://hdl.handle.net/2122/4054
Keywords: T waves
Ligurian Sea
SOFAR
frequency content
Abstract: Aim of this paper is to discuss on the T phases generated after the mb 6.5 earthquake that shook Algeria on May 21, 2003. The seismograms, recorded by a cluster of seismic stations located on the coast facing the Ligurian Sea, Northern Italy, some 800 km N-NE from the source, represent a good database able to shed some light on the recognition, propagation and characteristics of these quite uncommon phases. The occurrence and the recording of T phases are in fact due to particular conditions, and require both particular characteristics of the bathymetric slope and the existence of a clear path between the instruments and the earthquake’s source: these constraints are exactly realized in the north-western part of the Mediterranean Sea, whose coasts have been affected several times in the past by similar events. The preliminary investigations on the complex recorded seismogram show two different behaviours for stations close the coast and inland. In both cases, two distinct T phases (namely T1 and T2) are observed. In one case they have apparent velocities close to an average SOFAR channel, and are thus the recording of direct T phases. In particular, T1 is probably a precursor due to some scattering, while T2 is the direct T wave. Conversely, the recordings of the stations inland show apparent velocities that suggest back conversion of the original T to P and S waves and a crustal path. The frequency content of the T phases, as derived from the spectral analysis, reveals marked amplitude peaks also in the range 1-3 Hz, conversely to what was proposed by other authors for similar occurrences in other parts of the world. Since the geometry and shape of the SOFAR channel vary, it is highly likely that the spectrum is biased by the water conditions and the frequency content might change in different seas. Finally, the attenuation of the T phase does not depend on the actual distance of the receiver from the source but rather from the backconversion point: the amplitude varies thus with the in-land path and decreases proportionally to x−1.
Appears in Collections:04.06.09. Waves and wave analysis
Annals of Geophysics

Files in This Item:

File SizeFormatVisibility
01 Solarino.pdf6.07 MBAdobe 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
Del.icio.us

Citeulike

Connotea

Facebook

Stumble it!

reddit


 

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