What kind of ground movements can be measured by the PS Technique?
The PS Technique, like any other interferometric technique, allows measuring movements only along the satellite – Earth direction (called LOS = line of sight), not in all directions. The following figure shows what the LOS direction is. This means it is not possible to detect pure horizontal or vertical displacements, but of course, any movement along the LOS can be projected and therefore can give vertical or horizontal components. Furthermore, it is possible to detect only slow movements (roughly no more than 1 cm at every subsequent passage of the satellite on the same area). This limitation is due to the fact that what is really detected by the satellite is the variation in the satellite ground distance in fractions of a wavelength. The PS Technique is therefore optimal to detect subsidence or uplift phenomena, stability of buildings and slow creeping landslides.
