You are here

Deformation

Introduction The primal interest of GPS (GNSS) solutions is to monitor crustal deformation. The time span of the interest depends on objective, from relatively large scale like as plate motion and uplift due to melting of polar ice to small scale like as ground subsidence and collapse of cliff due to mining. There are two approaches to monitor crustal deformation with GNSS; (1) Static positioning with batch file available from several hours to one day (24 hours), and (2) Kinematic positioning which estimates position with sampling interval of observation (1Hz or 30 seconds, for example). There are two schemes to process GPS data; (1) Differential processing with reference of known station. The solution for the target station is relative motion from the reference station, and (2) Precise Point Positioning (PPP) which require precise satellite orbit and clock information. The processing scheme (1) can cancel out common error sources such as atmospheric delay, orbit delay, and clock delay with differential, but precision is worse with longer baseline which not common errors for the two stations are more dominant. Precision of the scheme (2) is generally common for any GPS stations anywhere, but it strongly depends on precision of satellite clock information. The time-series above shows coordinate variations for north, east, and height component, caused by Tokachi-oki earthquake. The red and green lines shows Bernese (network processing) and RTNet (PPP processing) solution, respectively. Both time-series agree well with each other. Daily coordinate solutions (by assuming coordinate doesn't change for one day time window) are plotted in th plot, and it shows that coordinate changed with the occurrence of the earthquake, and that relatively slow motion of the coordinates for the same direction with the step change after the earthquake (after slip).