Determination of active units with different kinematic property and their activity pattern in North China based on the data from GPS remeasurements |
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| Authors: | YANG Guo-hua HAN Yue-ping ZHANG Feng-lan |
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| Institution: | 1. First Crustal Deformation Monitoring Center, China Seismological Bureau,
2. Institute of Civil Engineer and Irrigation Works, Shandong University, |
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| Abstract: | Based on the high-accuracy data obtained from the GPS measurements carried out in 1992, 1995 and 1996, the isochronous active
units with different kinematic property inside the North China area have been distinguished, 4 active units and 1 transition
zone with distinct differential movement have been determined. They are Ordos-Yinshan unit, Yanshan unit, Shanxi-Hebei-Shandong
(Jin-Ji-Lu) unit, Jiaodong-Liaoning-Shandong (Jiao-Liao-Lu) unit and Yanshan-Hebei (Yan-Ji) transition zone. The relative
movements among the neighboring units in this period have been given. 1 The compressive movement between Ordos-Yinshan unit
and Yanshan unit is not obvious with an amount of 0.4±1.3 mm/a. 2 Jin-Ji-Lu unit moves E40°S off the Ordos-Yinshan unit and
the magnitude is 4.4±1.0 mm/a. 3 Relative to the Yan-Ji transition zone of differential movement, Yanshan unit shifts W38°N
with a value of 2.4±1.3 mm/a and Jin-Ji-Lu unit moves eastward 35° by south with an amount of 2.3±0.9 mm/a. 4 Jin-Ji-Lu unit
has a tensional left-lateral movement of 4.7±1.4 mm/a in the direction of E37°S relative to Yanshan unit. 5 Some area near
Tanlu belt which is located in the southern part of Jin-Ji-Lu block has a southward movement 14° by west with a magnitude
of 1.5±1.1 mm/a off the Jin-Ji-Lu unit. 6 Relative to Jin-Ji-Lu unit, Jiao-Liao-Lu unit has a trend of clockwise movement
with a tensional right-lateral motion at the north end which neighbors Yanshan unit and a compressive motion at the south
end. It should be noted that the errors given in the paper are obtained based on the divergence among the displacements of
the sites in the unit, rather than the value calculated from the displacement error of the sites. The analyzed results indicate
that: 1 Shanxi tectonic zone and Yan-Ji transition zone are the major tectonic active zones to show the frame and magnitude
of interior relative movement in North China area, and others are the secondary tectonic active zones; 2 The complete horizontal
deformation in the North China area is not homogeneous nor successive; 3 The kinetic model of North China area might be "mantle
dragging plus boundary coupling".
Foundation item: The National Key Basic Research Project Mechanism and Prediction of Continental Earthquakes (G1998040700). |
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| Keywords: | GPS measurement North China area active unit horizontal movement deformation mechanism |
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