The global plate motion rates Ω are not uniform in time and space. The rotation rates were larger than 0. 545°/Ma for Cocos, Philippine Sea, Pacific, Nazca, Australia, India and Arabia plates, but smaller than 0...The global plate motion rates Ω are not uniform in time and space. The rotation rates were larger than 0. 545°/Ma for Cocos, Philippine Sea, Pacific, Nazca, Australia, India and Arabia plates, but smaller than 0. 315°/Ma. for other plates. Compared to 1997. 0, the Ω values of the three oceanic plates in 2000. 0 increased by,respectively,2.4% ,2. 1% and 41.7%, and the northward movement rates of the the India plate and western part of the Australia plate increased by 3.38 mm/a on the average. The spatial distribution of earthquakes was dependent on earthquake magnitude. Earthquakes of 5.0 ≤ Mw 〈 7.0 were located mainly in plate-margin zones and intra-plate crustal deformation zones joining the southern margin of Eurasia plate. Earthquakes of Mw≥7.0 concentrated basically in the circum-Pacific and South Asia zones, but hardly in midocean-ridge seismic zones. Earthquakes of Mw ≥ 8.0 were located only in the margin zones of the India, Aus- tralia,Pacific and Nazca plates orthogonal to the direction of plate motion. Compared with previous eighteen years, global earthquake activity enhanced obviously after 1994, especially after 2001. The Ω value of a plate was closely related to the activity of strong earthquakes. The largest earthquakes were located in the front-margin zones of plates having the largest Ω values. Energy released by strong earthquakes comes mainly from kinetic energy of the plates. Global seismicity enhancement was caused mainly by the acceleration of the three oceanic plates. Larger enhancement of global earthquake activity lagged behind the movement acceleration of the three oceanic plates by four years.展开更多
Using thelast 5 years’ (1983—1988) global Satellite Laser Ranging (SLR) data of satellite Lageos, we have determined the present-day change rate of the baseline length among those SLR stations located in the North A...Using thelast 5 years’ (1983—1988) global Satellite Laser Ranging (SLR) data of satellite Lageos, we have determined the present-day change rate of the baseline length among those SLR stations located in the North America, South America, Indaia, Pacific and Eurasia plates. The precision estimated is better than 1 cm/a. The results of this determination agree with those obtained by the geologic tectonic rate model of Minster and Jordan (1978). This indicates that the motion of those regions located faraway from the plate boundary is probably stable in the past million years. In some regions at the plate boundary the result is found disagreed with the M/J model. For example, the determined change rate of the Monumeny Peak-Ouincy baseline across the famous San-Andreas transform fault is 2.9cm/a (M/J:5.3 cm/a). This might be explained with the hypothesis that periodic deformations occurring at the plate boundary and sudden deformations occurring only in the plate boundary zone. We have also found the展开更多
Heat flow in the Earth, from its hot interior to its relatively cool exterior, is the primary energy flow responsible for the dynamic nature of our planet. The motion of the plates excites a forced convective motion i...Heat flow in the Earth, from its hot interior to its relatively cool exterior, is the primary energy flow responsible for the dynamic nature of our planet. The motion of the plates excites a forced convective motion in the mantle, and this plate-driven mantle flow will strongly modulate the temperature field in the mantle because of the relatively high Peeler number of the mantle dynamic system. Here the role of the plate-driven mantle flow in the observed global heat flow is examined. The result reveals that the main feature of the distribution of the observed heat flow at the surface of the Earth matches well with the prediction and nearly one half of the average heat flow can be attributed to the thermal effect of the plate-driven mantle flow.展开更多
基金supported by the China National Key Basic Research Program (2007CB411702)the National Natural Science Fundation of China(40474036,40474039)
文摘The global plate motion rates Ω are not uniform in time and space. The rotation rates were larger than 0. 545°/Ma for Cocos, Philippine Sea, Pacific, Nazca, Australia, India and Arabia plates, but smaller than 0. 315°/Ma. for other plates. Compared to 1997. 0, the Ω values of the three oceanic plates in 2000. 0 increased by,respectively,2.4% ,2. 1% and 41.7%, and the northward movement rates of the the India plate and western part of the Australia plate increased by 3.38 mm/a on the average. The spatial distribution of earthquakes was dependent on earthquake magnitude. Earthquakes of 5.0 ≤ Mw 〈 7.0 were located mainly in plate-margin zones and intra-plate crustal deformation zones joining the southern margin of Eurasia plate. Earthquakes of Mw≥7.0 concentrated basically in the circum-Pacific and South Asia zones, but hardly in midocean-ridge seismic zones. Earthquakes of Mw ≥ 8.0 were located only in the margin zones of the India, Aus- tralia,Pacific and Nazca plates orthogonal to the direction of plate motion. Compared with previous eighteen years, global earthquake activity enhanced obviously after 1994, especially after 2001. The Ω value of a plate was closely related to the activity of strong earthquakes. The largest earthquakes were located in the front-margin zones of plates having the largest Ω values. Energy released by strong earthquakes comes mainly from kinetic energy of the plates. Global seismicity enhancement was caused mainly by the acceleration of the three oceanic plates. Larger enhancement of global earthquake activity lagged behind the movement acceleration of the three oceanic plates by four years.
文摘Using thelast 5 years’ (1983—1988) global Satellite Laser Ranging (SLR) data of satellite Lageos, we have determined the present-day change rate of the baseline length among those SLR stations located in the North America, South America, Indaia, Pacific and Eurasia plates. The precision estimated is better than 1 cm/a. The results of this determination agree with those obtained by the geologic tectonic rate model of Minster and Jordan (1978). This indicates that the motion of those regions located faraway from the plate boundary is probably stable in the past million years. In some regions at the plate boundary the result is found disagreed with the M/J model. For example, the determined change rate of the Monumeny Peak-Ouincy baseline across the famous San-Andreas transform fault is 2.9cm/a (M/J:5.3 cm/a). This might be explained with the hypothesis that periodic deformations occurring at the plate boundary and sudden deformations occurring only in the plate boundary zone. We have also found the
基金Project supported by the National Natural Science Foundation of China (Grant No. 49774231).
文摘Heat flow in the Earth, from its hot interior to its relatively cool exterior, is the primary energy flow responsible for the dynamic nature of our planet. The motion of the plates excites a forced convective motion in the mantle, and this plate-driven mantle flow will strongly modulate the temperature field in the mantle because of the relatively high Peeler number of the mantle dynamic system. Here the role of the plate-driven mantle flow in the observed global heat flow is examined. The result reveals that the main feature of the distribution of the observed heat flow at the surface of the Earth matches well with the prediction and nearly one half of the average heat flow can be attributed to the thermal effect of the plate-driven mantle flow.
