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Zou Z.,Wuhan University | Zou Z.,Institute of Seismology | Zou Z.,Crustal Movement Laboratory | Luo Z.,Wuhan University | And 5 more authors.
Cehui Xuebao/Acta Geodaetica et Cartographica Sinica | Year: 2012

The decorrelation and Gaussian smoothing method is implemented in GRACE monthly gravity field products to obtain annual and seasonal gravity changes in Japan and its vicinity, as well as time series gravity changes of several points. Results show regional gravity fields in Japan and its vicinity varied from positively to negatively and from area to area in five years before the Japan M w9.0 earthquake, obviously positive to negative gravity changes were formed in 1~2 years. Time series gravity changes of several points indicate the Japan earthquake displayed the similar time variation gravity phenomenon with the 1976 Tangshan earthquake in China. These results reflect mass migration, mass movement and energy accumulation in Japan and its vicinity before the earthquake occurred.

Xing L.,China Earthquake Administration | Xing L.,Crustal Movement Laboratory | Xing L.,Wuhan University | Sun W.,China Earthquake Administration | And 5 more authors.
Acta Geodaetica et Cartographica Sinica | Year: 2011

The crust of Tibetan Plateau is still uplifting and thickening nowadays by the collision between the Indian plate and Eurasian plate which revealed by the geological and tectonic results, it is also a complex and hot problem which has been studying by global geoscientists. However, almost no quantitative evidence shows whether the plateau is still uplifting or thickening. In this paper we present geodetic evidence of mass loss beneath the Tibetan Plateau and increasing crust thickness which is 3. 9±0. 8 cm/a by using high accuracy absolute gravity data and the authoritative GPS measurements results, finally we give a simple geodynamic model illustrating crustal thickening of the Tibetan Plateau.

Kang K.,China Earthquake Administration | Kang K.,Crustal Movement Laboratory | Li H.,China Earthquake Administration | Li H.,Crustal Movement Laboratory | And 5 more authors.
Terrestrial, Atmospheric and Oceanic Sciences | Year: 2011

Hydrological influences on a local gravity field may reach amplitudes on the order of 10 microgals. Since 2007, fifteen Microg LaCoste gPhones have been successively installed in gravity stations in China. The outputs from gPhones include ten data channels with second sampling such as raw gravity, corrected gravity, long level data and cross level data, ambient and sensor temperature, ambient and sensor pressure, and others. In this study, we select six stations in northwest China (GaoTai, LaSa, LanZhou, ShiQuanHe, WuShi, XiAn) and one station in the northeast (HaiLaEr). We have modeled the major tides (earth solid tide, ocean tide and pole tide), corrected for atmospheric loading effects using local measurements, fitted instrumental drift using segmental fitting based on the distinct characteristics of gravimeter drift, and ultimately obtained the monthly residual gravity with amplitudes of 10 ∼ 20 microgals. We find that the results obtained by the gravimeter for those stations with stable conditions and no large disturbances are obviously correlated with hydrologic loading as modeled by the Global Land Data Assimilation System and Climate Prediction Center. We also notice that at some stations there are obvious phase lags with a period of three months or more between the residual gravity and the influence of hydrological loading. These large discrepancies may be associated with local hydrologic effects, local topography or some other complex tectonic movement and geodynamical mechanism, which were not considered in this paper.

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