Mapping surface deformation in Red River Fault Zone using spaceborne SAR interferometry

The South China block and Indochina block were separated by the Red River Fault Zone (RRFZ). From geological point of view, this zone is considered as complex geological structures that has brought dramatic geological evolution to the Red River delta of northern Vietnam. Red River delta, where is a highly populated region, maintaining an area of 15,000 square kilometers, mostly composed by mountainous and drainage area. This is a developing area, characterized by active economic development and high population density. Despite of locating in a big fault zone, the displacement of the ground in this area has never been well monitored. This study focuses on the surface evolution of the Red River Delta in the recent years. Due to the diverse climatic condition, distinct range of vegetation covers as well as a wide area needed to be observed, Persistent Scatterers Synthetic Aperture Radar (PSInSAR) technique is considered as a cost-effective and appropriate approach for this area. We use 40 ALOS PALSAR images, which belonging to 3 different scenes, to derive the deforming rate of three regions related to RRFZ. The results show that the area of northern Vietnam experience high-rate land subsidence in Yen Bai city due to the active of some fault segments in this area. The subsidence rate reached up to -60 mm per year. Monitoring scenes in Viet Tri and Lao Cai city do not experience noticeable deformation.