HR: 1340h
AN: T33A-1340    [Abstracts]
TI: High-resolution Surface Wave Tomography of the Western and Central Alps
AU: * Fry, B
EM: bill.fry@erdw.ethz.ch
AF: ETH-Hoenggerberg Institute for Geophysics, HPP, Zurich, 8093 Switzerland
AU: Boschi, L
EM: lapo@tomo.ig.erdw.ethz.ch
AF: ETH-Hoenggerberg Institute for Geophysics, HPP, Zurich, 8093 Switzerland
AU: Giardini, D
EM: giardini@seismo.ifg.ethz.ch
AF: ETH-Hoenggerberg Institute for Geophysics, HPP, Zurich, 8093 Switzerland
AB: Global resolution of surface wave phase velocity maps is limited by data coverage. However, on local or regional scales data coverage can be quite dense in areas with closely spaced seismometers. It is possible to utilize data from high-density arrays by overparameterizing the inversion in areas with denser ray-path coverage. Two Swiss broadband arrays create a dense seismic network in and around Switzerland. The Swiss Digital Seismic Network (SDSNet) is a dense permanent array including 29 STS-2 broadband seismometers with a station spacing of 40-50 km. To supplement data from this array, 7 temporary STS-2 broadband seismometers of the TomoCH (Tomography of Confederatio Helvetica) array have been installed peripherally to Switzerland to increase the array aperture to approximately 5 degrees by 2 degrees. Source/receiver dispersion curves have been calculated by fitting synthetic waveforms to frequency-filtered event traces containing fundamental Rayleigh and Love waves. These observations have been merged with data previously collected and measured in European and global studies. The resulting comprehensive database has ray-path coverage sufficiently dense to allow relatively stable, lightly damped, highly-parameterized inversion for phase velocity perturbations in central-western Europe. Subsequent to dispersion measurements, a linearized inversion algorithm has been used to obtain phase velocity maps by fitting the measured dispersion curves. Observations of phase velocity perturbations contribute to high-resolution studies of the lithosphere beneath the Alps with the ultimate goal of understanding the dynamic processes that formed and stabilize these mountains.
DE: 7255 Surface waves and free oscillations
DE: 7294 Instruments and techniques
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 7218 Lithosphere and upper mantle
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting