CHINESE JOURNAL OF GEOPHYSICS GPS

46 2 2003 3 CHINESE JOURNAL OF GEOPHYSICS Vol. 46, No. 2 Mar., 20 0 3 GPS, 430077 GPS,,,,., 8. 1 21. 8 mmπa. 23Ma, 18mmΠa,,,. GPS 0001-5733(2003) 02-0185 - 06 P542 2001-10 - 27,2002-10 - 28 A STUDY ON CONVERGENCE RATE OF THE INDIA PLATE TO ERUASIA SUBDUCTION BENEATH QINGHAI2XIZANG PLATEAU INVERSION RESULTS FROM GPS OBSERVATIONAL DATA WANG YONG XU HOUZE Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China Abstract The Convergence rate of the India plate to Eurasia subduction beneath Qinghai2Xizang Plateau is inversed on the basis of the GPS data observed by Chinese and abroad Institutes using the model of the India plate to Eurasia subduction and dislocation in two layered self2gravitational elastic half space. Present convergence rare of the India plate is obtained under the geodetic data constrains. The results show that the present convergence rate of the India plate is 21. 8 mmπa with a dipping 8. 1 to the north. This is in good agreement with various geologic predictions of 18mmΠa in past 23 million year implying a stable convergence rate of the India plate in a very long duration. Key words Plate subduction, GPS, Elastic dislocation, Geodetic inversion Qinghai2Xizang Plateau. 1,GPS 10-9,,.,GPS [15 ],GPS, GPS.,.,, ;., ( KZCX2-106) (40274020).,,, 1964, 1985,1995,. E2mail : ywang @asch. whigg. ac. cn

186 (Chinese J. Geophys. ) 46,?,?,.,,.,.,.,, [510 ]. Bilham [5 ]. Jackson [11,12 ] GPS. GPS, GPS, GPS,. 2 GPS GPS, : (1) GPS ( IGS). 48 GPS,. ( ) ( ) (),. (2), 1992 1994 1996 3 23 GPS, 3, 3., ITRF GPS GAMIT. 1 GPS (3). 1993 1997 GPS,,,,14, 1470km, 60km,, Turbo Rogue, GAMIT.,1995 1997 IGS,ITRF97 (4). 19911997,, 24, IGS. 1991, 1015mm,1995 1997,5 6mm,JPL GIPSY ITRF. (5). 1992 1996 ( ) GPS, 6, GAMIT ITRF., 1 GPS [15 ], [610 ]. Table 1 The comparison of GPS observational result consistency in Tibetan Plateau ( ) ( ) ( ) ( ) (mmπa) (mmπa) () 29 39 91 06 19. 3 2. 8 23. 2 2. 5 [5 ] 29 39 91 06 21. 5 1. 2 20. 7 1. 0 [2 ] 29 39 91 06 21. 5 0. 9 24. 7 0. 3 [1 ] 33 06 91 53 27. 7 6. 4 16. 4 3. 5 [4 ] 33 03 91 52 23. 8 2. 4 17. 1 1. 8 [1 ] 36 26 94 52 15. 8 8. 4 12. 3 4. 5 [2 ] 36 15 94 52 11. 9 2. 2 14. 2 1. 5 [1 ] 28 55 89 36 28 18 86 01 19. 1 4. 5 26. 7 2. 5 [2 ] 17. 4 1. 8 28. 2 1. 7 [4 ] 16. 9 5. 4 30. 0 3. 1 [2 ] 14. 5 2. 3 44. 3 2. 0 [4 ]

2 : GPS 187 1 GPS [610 ], GPS [15 ] Fig. 1 The movement vectors of GPS observational points in Qinghai2Xizang Plateau relative to Eurasia plate. Openarrowshowthe velocityofplate andfault determinedfroma varietyof geologic data [610 ] show the movement velocity determined from GPS observation [15 ], solidarrow, GPS,1. 1,,.,1 49 GPS. 3 2 INDEPTH [13 ], 1 GPS,2. 2 [12 ],,,,,., 3 (+ ). [14 ] 2 [13 ] Fig. 2 A model of India to Eurasia subduction [13 ]

188 (Chinese J. Geophys. ) 46 3 Fig. 3 Dislocation model of two layered self2gravitational elastic 2 u + 1 1-2 half space - < - g e z u + g 2 < = - 4G u = 0, ( u e z ) (1) u, (2), u ( r,, z),, e z z, G,, g. (1) (2).,[15,16 ]. j m j,(1) (2) i ( x 0, y 0 ), S i ( m j ) = ( u yi - u y0 ) 2 + ( u xi - u x0 ) 2 = u 2 y i +u 2 x i, f ( m j ) = (u yi - u 0 y ) 2 + (u xi - u 0 x ) 2 i N - j,u 0 y u 0 x GPS, N. m j, m j, (3) (4) a j m j b j, (5) (5), (4) m j. 4 3, 10,L W D U 1 U 2 U 3, 0 < 0. U 3,9. [17 ], (4) (5)., Okada [18 ] (3),,.,. : H 90km, Lame 1 1 3. 0 10 11 g cm - 1 s - 2, 1 3. 0 g cm - 3 ;Lame 2 2 3. 5 10 11 g cm - 1 s - 2, 2 3. 5g cm - 3. 1 GPS,,,.,, 1 GPS,,. INDEPTH [13 ], 18 7mmΠa [6,7 ],,L = 1500km, W = 500km, D = 50km, U 2 = 30mmΠa. 4. 4,32, 2mmΠa., 32 42 GPS.,,, (3) S i ( m j ). 2,,,Larson [12 ] 2. 5 6 2

2 : GPS 189 4 Fig. 4 The displacement vector of modeling computation in Qinghai2Xizang Plateau due to the India to Eurasia subduction 2 Table 2 The parameters and results of inversion L W D U 1 U 2 0 < 0 f (km) (km) (km) ( ) ( ) (mmπa) (mmπa) ( ) ( ) (mm) 1400 400 25 10 105N 10-10 86 28 1300 300 10-180 - 180-30 - 30 85 27 1500 500 80 180 180 30 30 87 29 (1) 1452 485 20. 5 8. 5 104. 3N 3. 87-20. 2 86. 2 27. 7 6. 36 (2) 1496 492 19. 8 8. 1 106. 5N 3. 53-21. 8 85. 9 27. 9 4. 24 (3) 22. 0 9. 7 104. 4N 3. 50-20. 1 (1), (2), (3) [12 ]. 5 Fig. 5 The displacement vector computed of Tibet Plateau due to the subduction of India to Eurasia plat from the inversed model parameters GPS GPS. 2, 6 GPS Fig. 6 The residual distribution of the computed displacements with GPS observational results Larson [12 ], f,. 5,GPS GPS ( 1),(6),

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