jgg     2014 34 (5):  35-39    ISSN: 0412-1961  CN: 21-1139/TG VERTICAL MOTION OF NORTH CHINA INFERRED FROM  DENSE GPS NEASUREMENTS 1）GNSS Research Center，Wuhan University，Wuhan 430079 2）Key Laboratory of Earthquake Geodesy，Institute of Seismology，CEA，Wuhan 430071 Received: 2013-12-31  Revised: null  Online: 2014-09-26 Supporting info