HR: 09:00h
AN: S11D-03    [Abstracts]
TI: Imaging Kilauea Volcano Magmatic System Using an Efficient Algorithm for Double-Difference Tomography and Cross-Spectral Time-Delays
AU: MONTEILLER, V
EM: Vadim.Monteiller@univ-savoie.fr
AF: LGIT, Universite de Savoie, Le Bourget-du-Lac, 73376 France
AU: * GOT, J
EM: jlgot@univ-savoie.fr
AF: LGIT, Universite de Savoie, Le Bourget-du-Lac, 73376 France
AU: VIRIEUX, J
EM: viri@geoazur.unice.fr
AF: Geosciences Azur, Universite de Nice - Sophia Antipolis, Valbonne, 06560 France
AU: OKUBO, P G
EM: pokubo@usgs.gov
AF: USGS - HVO, Hawaii National Park, Hawaii National Park, HI 97560 United States
AB: We have designed a method based upon double-difference relocation and tomography to image, as accurately as possible, a heterogeneous medium containing seismogenic objects. Our approach has been not only to introduce double-difference in tomography, but rather to partly revisit tomographic schemes for chosing accurate and adapted numerical strategies. We used a finite-difference solution to the Eikonal equation (Podvin and Lecomte, 1991) for travel-time computation and a Tarantola-Valette approach for both the double-difference and the 3D tomographic inversion to find accurate earthquake locations and seismic velocity estimates. Though an efficient estimation of the squared root of the inverse model covariance matrix in the case of the gaussian correlation function, we use correlation length and a priori model variance criteria to determine the optimal solution. Double-difference relocation of similar earthquakes is performed in the optimal velocity model, making absolute and relative locations less biased by the velocity model. Double difference tomography is achieved by using high-accuracy time delay measurements. These algorithms have been applied to earthquake data recorded in the vicinity of Kilauea and Mauna Loa volcanoes for imaging the volcanic structures. They allow to find stable and detailed velocity models : regional tomography allows to retrieve unambiguously the structure of Hawaii island, and double difference tomography shows a detailed image of the southern Kilauea Caldera - Upper East Rift Zone magmatic complex.
DE: 7280 Volcano seismology (8419)
DE: 7203 Body wave propagation
SC: Seismology [S]
MN: 2004 AGU Fall Meeting