The upper mantle beneath the Philippine Sea region from waveform inversions

Abstract

Abstract. We present a three-dimensional S-velocity

Lateral Variations of Rayleigh-Wave Dispersions in the Philippine Sea Region

“…Later, Nakamura and Shibutani (1998) modified this structural model by the inversion of more than 900 Rayleighwave phase-velocities. The results of both studies indicate that there are low S-wave velocities in the West Philippine Basin that are related to the extinct Central Basin Ridge (e.g., Lebedev et al 1997;Nakamura and Shibutani 1998). Rayleigh-wave phase velocities obtained from the broadband OBS array in the Philippine Sea region also give systematically lower values than those obtained in the Pacific for comparable geological ages (Isse et al 2004).…”

“…This can be interpreted as a variation in depth between the Philippine Sea Plate and its surrounding plates (Lebedev et al 1997). Additional high velocity features are located to the east and southeast of the studied region, i.e., the westernmost Pacific Ocean and the Caroline basin all reveal a high velocity related to plate cooling where the seafloor age is older.…”

“…Past studies of surface waves across the Philippine Sea and the surrounding areas have provided some important information about lateral variations in plate thickness and upper mantle shear velocities (e.g., Seekins and Teng 1977;Yu and Chang 1991;Oda and Senna 1994;Lebedev et al 1997;Nakamura and Shibutani 1998). Although there are some differences between the results, especially for plate thickness in relation to geological and topographic features, the fact that there is lateral variation in structure beneath the Philippine Sea is revealed.…”

“…Since 1995, tomographic inversion with huge high-quality dispersion curves has been extensively used to establish global-scale surface wave group-and phase-velocity maps (e.g., Ekström et al 1997;Larson and Ekström 2001). Regional-scale tomographic images of surface waves, such as in the Philippine Sea or China, have been also made to investigate their tectonics implications (e.g., Lebedev et al 1997;Nakamura and Shibutani 1998;Hwang 1999). The 3-D shear velocity structure of the upper mantle to depths of 200 -300 km beneath the Philippine Sea has been derived by Levedev et al (1997) from the waveform inversion of about 300 Rayleigh waves.…”

Three-dimensional shear wave velocity structure in the upper mantle beneath the Philippine Sea region

“…The variations of lithosphere thickness can be mapped from the detail seismic structure obtained three-dimensionally. Lebedev et al (1997) inverted 281 vertical-component broad band waveforms recorded at Australia and around the Philippine Sea. They presented a three-dimensional shear wave velocity structure of the upper mantle beneath the Philippine Sea.…”