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Study on Surface Wave Dispersion Characteristics in the
Philippine Sea BasinWen-Lung WangAbstract In this study, the
group and phase velocities along 123 Rayleigh-wave paths and 108
Love-wave paths have been analyzed at the periods from 20 to 100
seconds for Rayleigh waves and from 28 to 100 seconds for Love
waves, respectively, by using the single-station method. The
Philippine Sea Basin and surrounding area are divided into 67
blocks with size of 3.4°×3.4°in latitude and longitude. The
regionalized group and phase velocities for each block are
determined by the pure-path method with single-valu Comparing
the results of Rayleigh-wave and Love-wave group and phase
velocities, we find that the resolution of phase velocities is
better than that of group velocities. Resolution of Love waves
is also slightly less than that of Rayleigh waves because of the
uneven path coverages. However, Love waves may better reflect
the variation of high heat flow, geomorphologic features and
geological ages than Rayleigh waves. Although the variation
of group velocity in this study, are similar to the results of
some previous studies which divided the Philippine Sea Basin
into several subregions based on geomorphologic features and
geological ages, this study provides more detailed velocity
variation including group and phase velocities in this area. The
lateral variation of velocities in the Philippine Sea Basin are
generally demarcated by the Palau-Kyushu Ridge. Velocities are
highest in the West Philippine Basin and decreas From this
study, we find that the patterns of regionalized velocity
distribution become very simple for periods longer than 70
seconds, suggesting that the lateral variation of velocities in
upper mantle of the whole Philippine Sea Basin at the depth
below 100 km may not be so obvious.
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