Abstract: This paper shows the surface expansion phenomenon before Kunlun earthquake on September 14, 2001 by using GPS surveying data. Four adjacent triangles are combined by 6 GPS stations around the epicenter of Kunlun earthquake. Regional surface expansion of the 4 triangles is calculated. Its space distribution and temporal change characteristics are analyzed. The evidence of surface expansion before the earthquake is approved using large scale surveying data. This may be used for judging the precursor of strong earthquakes.

Key words: Kunlun Earthquake, GPS surveying, Surface expansion