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Estimating Crustal Heterogeneity from Double-difference Tomography

Authors
  • Got, Jean -Luc1
  • Monteiller, Vadim1
  • Virieux, Jean2
  • Okubo, Paul3
  • 1 Université de Savoie, Laboratoire de Géophysique Interne et Tectonophysique, le Bourget-du-Lac, 73376, France , le Bourget-du-Lac (France)
  • 2 Géosciences Azur, Sophia-Antipolis, Valbonne, 06560, France , Valbonne (France)
  • 3 USGS - Hawaiian Volcano Observatory, Hawaii National Park, Hawaii, 97560, U.S.A , Hawaii (United States)
Type
Published Article
Journal
pure and applied geophysics
Publisher
Birkhäuser-Verlag
Publication Date
Mar 01, 2006
Volume
163
Issue
2-3
Pages
405–430
Identifiers
DOI: 10.1007/s00024-005-0022-x
Source
Springer Nature
Keywords
License
Yellow

Abstract

Seismic velocity parameters in limited, but heterogeneous volumes can be inferred using a double-difference tomographic algorithm, but to obtain meaningful results accuracy must be maintained at every step of the computation. MONTEILLER et al. (2005) have devised a double-difference tomographic algorithm that takes full advantage of the accuracy of cross-spectral time-delays of large correlated event sets. This algorithm performs an accurate computation of theoretical travel-time delays in heterogeneous media and applies a suitable inversion scheme based on optimization theory. When applied to Kilauea Volcano, in Hawaii, the double-difference tomography approach shows significant and coherent changes to the velocity model in the well-resolved volumes beneath the Kilauea caldera and the upper east rift. In this paper, we first compare the results obtained using MONTEILLER et al.'s algorithm with those obtained using the classic travel-time tomographic approach. Then, we evaluated the effect of using data series of different accuracies, such as handpicked arrival-time differences (``picking differences''), on the results produced by double-difference tomographic algorithms. We show that picking differences have a non-Gaussian probability density function (pdf). Using a hyperbolic secant pdf instead of a Gaussian pdf allows improvement of the double-difference tomographic result when using picking difference data. We completed our study by investigating the use of spatially discontinuous time-delay data.

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