A methodology for inversion of broadband seismic waveforms for elastic and anelastic structure and its application to the mantle transition zone beneath the Northwestern Pacific

摘要

We develop a quantitative and objective methodology for inversion of body-wave waveform data for elastic and anelastic structure and apply it to the upper mantle and mantle transition zone (MTZ) beneath the Northwestern Pacific, using PREM as the starting model. We use the singular value decomposition (SVD) as the basis for our inversion and use Akaike's Information Criterion (AIC) to evaluate the statistical significance of the models. Although the resulting models are preliminary, we obtain an average positive S-wave velocity anomaly in the MTZ beneath the Philippine Sea Plate and the Japan Sea. We also find a negative S-wave velocity anomaly in the depth range 300-400. km beneath the subduction zone to the east of northern Japan and its southern extension beneath the Izu-Bonin-Marianas arc. Our inversions obtained a lower Qμ, as compared to PREM, for all of the subregions.