Large-Scale Present-Day Plate Boundary Deformations in the Eastern Hemisphere Determined from VLBI Data: Implications for Plate Tectonics and Indian Ocean Growth

作者：Akilan A^*; Azeez K K Abdul; Schuh H; Yuvraaj N

来源：Pure and Applied Geophysics, 2015, 172(10): 2643-2655.

DOI：10.1007/s00024-014-0952-2

• VLBI
• plate tectonics
• crustal deformation
• Eastern hemisphere
• Indian Ocean
• Hurst exponent
• strain rate

The dynamics of the planet Earth are manifestations of diverse plate tectonic processes which have been occurring since the Archean period of the Earth's evolution and continue to deform the plate boundaries. Very long baseline interferometry (VLBI) is an efficient space geodetic method that enables precise measurement of plate motion and associated deformations. We analyze here VLBI measurements made during a period of approximately three decades at five locations on the Eastern hemisphere of the globe, which are geographically distributed over five continents (plates) around the Indian Ocean. Computed rate of change of baseline length show the deformation pattern and its rate at the boundaries between the major tectonic plates constituting the Eastern hemisphere of the Earth. The African (Nubian) and Antarctic plates are moving apart at 13.5 mm/year, which is mostly attributed to spreading of the South West Indian Ridge. Similarly, spreading of 59.0 mm/year is observed for the South East Indian Ridge that separates the Antarctic and Australian plates. Shortening at the rate of 3.9 mm/year is estimated across the subduction boundary between Africa (Nubia) and Eurasia. Similar convergence is evident between the Australian and Sunda blocks (of the Eurasian plate). The associated deformation of -54.8 mm/year seems to be chiefly accommodated along the Banda arc system, where the Australian plate is subducting under the Sunda block. VLBI sites within the Eurasian plate, Wettzell in Germany, and Seshan on the South China block, are moving apart at 3.6 mm/year. This relative motion between locations on the same plate is interpreted as a result of the deformation process along a large strike-slip fault, which is identified as the Western boundary of the South China block. Expansion of the Indian Ocean, at +91.5 m(2)/year, is also estimated from the rate of deformation estimated within the five baselines studied here. From the Hurst exponent values, which are indicators of the future trend of time series data, we predict deceleration of the various tectonic processes occurring at present.

• 出版日期2015-10