Near-field surface deformation during the April 20,2013,Ms7.0 Lushan earthquake measured by 1-Hz GNSS

The April 20,2013,Ms7.0 Lushan earthquake was successfully recorded by closely spaced Continuous Global Positioning System (CGPS) stations owned by the Crustal Movement Observation Network of China (CMONC).The 1-Hz GNSS data from eight CGPS stations,which are located between 30 km and 200 km from the hypocenter,were processed within quasi-real-time.The near-field surface deformation indicated the following characteristics:the near-field movements were limited to several centimeters;the peak of the deformation wave was significantly larger than the static permanent offset;at the beginning of the event,the north wall of the fault moved to the southeast as the south wall moved to the southwest;station SCTQ,which was the closest station to the hypocenter at 30 km,had the largest static permanent displacement of 2 cm;the peaks of the deformation waves were 1.5 cm,5 cm and 3 cm,to the east,the south and vertically upward,respectively;and the peaks of velocity and acceleration,derived from the deformation,were 3.4 cm/s and 5.3 cm/s2,respectively.