Determination of Height Variation of Qomolangma(Mt. Everest)and CrustalMovement in Its Northern Surrounding Area with GPS Technique

Since 60's of the 20 Century China has carried out six geodetic campaigns(1966,1975,1992,1998,1999 and 2005 respectively) for measuring the height of Qomolangma(Mt.Everest,ME) and the crustal movement in its northern surrounding area(area in shorter),independently or in cooperation with foreign countries.Large scale geodetic field work,data processing and scientific research have been done,dealing with positioning,height determination,gravimetry,astronomical measurement and atmospheric reflection observation etc.The height variation of the snow summit of ME and the crustal movement,horizontal and vertical,of the area determined with GPS and leveling techniques in this passing years have been briefly reviewed and analyzed.The height variation of the ME snow summit is,according to the GPS measurement in 1992 and 2005,that 25 cm has been descending in the past 13 years,i.e.with the descending rate of 1.8 cm/a.The average horizontal crustal movement in the area,according to the GPS measurement in 1992,1998 and 2005,moves in the direction of 45 NE at the speed of 4 cm/a.The average vertical crustal movement in the area is,according to the multi terms re-leveling between 1966 and 2005,that the ascending rate is 1.8 mm/a.A non-stationary phenomenon both in time and space of the horizontal and vertical crustal movement in the area is found.