STUDY LITHOSPHERE STRUCTURE OF EURASIAN AND THE SURROUNDING AREA BY SURFACE WAVE METHOD

This paper deals with the high resolution surface wave tomography in Eurasia and its surrounding seas(20°W~160°E, 20°S~80°N).More than 12 000 long-period waveforms from about 2000 events (7.0 ≥ M ≥ 5.0) recorded at 114 digital seismic stations from CDSN, GDSN, GSN and GEOSCOPE network in Eurasia and its surrounding regions were used in this paper.The results show that in Eurasia and its surrounding seas, the lithosphere thickness is from 40~60 km (continental rift zone) to 190~220 km (Craton region), the lithosphere velocity range is 4.30~4.80 km/s.Until 400 km depth, the various differences between the horizontal plate and block gradually decrease.In precambrian craton and block, the lithosphere is very thick and high V_S, the asthenosphere is very thin or non-existent;in marginal sea and Phanerozoic orogenic regional, lithosphere is thin and low V_S, the asthenosphere is very large.Distinctive features of oceanic plates is uncommonly high V_S in lithosphere, and abnormally low V_S in asthenosphere, the rate of mutation is very sharp in velocity-depth curves.