HR: 1340h
AN: S23B-1392    [Abstracts]
TI: Inversion of body-wave waveform data for elastic and anelastic transition-zone structure in and around Japan
AU: * Fuji, N
EM: fuji@eps.s.u-tokyo.ac.jp
AF: Department of Earth and Planetary Science, Graduate School of Science, the University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
AU: Kawai, K
EM: kenji@geo.titech.ac.jp
AF: Department of Earth and Planetary Science, Graduate School of Science, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo, 152-8550, Japan
AU: Geller, R J
EM: bob@eps.s.u-tokyo.ac.jp
AF: Department of Earth and Planetary Science, Graduate School of Science, the University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
AB: Inversion of body-wave waveform data for elastic and anelastic transition-zone structure in and around Japan Nobuaki Fuji, Kenji Kawai and Robert J. Geller We have developed new methods to invert seismic waveform data for localized seismic structure. We use these methods to invert for the fine structure of the mantle transition zone in and around Japan using broadband data from regional arrays. Our methods use tools we have developed for performing 'static corrections' for the complex crustal structure in and around Japan. We conduct static correction by making a time shift which gives the best correlation coefficient for the first arrival S phase. We also have used other methods for time shifting such as onset pick time shift, but we found that the results of the inversion do not greatly differ. In order to stabilize the inversion we use automated data selection criteria, which limit the amplitude ratio of the synthetic seismogram to the observed seismogram to be between 0.3 and 3.0, and require a value above 0.5 for the correlation coefficient. The amplitude ratios (synthetic/observed) are systematically large for the initial (PREM) anelasticity model, so we invert simultaneously for both Q and elastic structure. We invert the transverse components of long-period (20-200 s) body-wave data from the NIED F-net array. The target regions lie beneath Hokkaido and the Philippines Sea at depths between 200 km and 700 km. The dataset used in this study consists mainly of triplication S phases that sample the mantle transition zone. It is difficult to analyze such data using previous methods, but our methods can handle such data. Models from studies of this type should contribute to improving our knowledge of the thermal state and proportion of water present in the upper mantle.
DE: 7208 Mantle (1212, 1213, 8124)
SC: Seismology [S]
MN: 2007 Fall Meeting