Yangbajain contains the largest geothermal energy power station in China.Geothermal explorations in Yangbajain first started in 1976,and two plants were subsequently built in 1981 and 1986.A large amount of geothermal...Yangbajain contains the largest geothermal energy power station in China.Geothermal explorations in Yangbajain first started in 1976,and two plants were subsequently built in 1981 and 1986.A large amount of geothermal fluids have been extracted since then,leading to considerable surface subsidence around the geothermal fields.In this paper,InSAR time series analysis is applied to map the subsidence of the Yangbajain geothermal fields during the period from December 2011 to November 2012 using 16 senses of TerraSAR-X stripmap SAR images.In the case of the TerraSAR-X data,most orbital fringes were removed using precise orbits during the interferometric processing.However,residual orbital ramps remain in some interferograms due to the uncertainties in the TerraSAR-X orbits.To remove the residual orbital ramps,we estimated a best-fit‘twisted plane’for each epoch interferogram using quadratic polynomial models based on a network approach.This method removes most of the long-wavelength signals,including orbit ramps and atmospheric effects.The vertically stratified component(Topography Correlated Atmospheric Delay,TCAD)was also removed using a network approach.If the influence of seasonal frozen ground(SFG)is not taken into consideration,our results show that the subsidence rate around power plant I(the south plant)is approximately 20 mm/yr with a peak of 30 mm/yr.The subsidence rate around power plant II(the north plant)is approximately 10 mm/yr,when accounting for the influence of SFG on the power plant and its surrounding ground surface.Our results show that ground motion is caused by seasonal frozen ground and is strongly related to the temperature change.展开更多
ABSTRACT Conducting long measurements of infrastructure deformation is a critical engineering task.Conventional methods are both timeconsuming and expensive,limiting their use for large-scale applica-tions.The synergy...ABSTRACT Conducting long measurements of infrastructure deformation is a critical engineering task.Conventional methods are both timeconsuming and expensive,limiting their use for large-scale applica-tions.The synergy of synthetic aperture radar(SAR)and geographic information systems(GIS)offers a complementary approach.This study focuses on the feasibility of using time series analysis of L-band PALSAR-2 images to discover land displacements in Istanbul and Kocaeli,significant industrial and residential areas in Turkey.PALSAR-2 phase and intensity information were analyzed.For phase analysis,14 L-band images from 2014 to 2021 were taken into account.Small baseline subset(SBAS)analysis was performed using 44 pairs,and results of the velocity,coherence and back-scattering values are presented.Coherence of all pairs and their correlations were calculated.Principal Component Analysis(PCA)reduced the dimension of coherence pairs,enhancing feature extraction and the final geocoded velocity map revealed a fastest subsidence rate of−58 mm/yr and a mean subsidence of−20 mm/yr.These findings were confirmed through mean vertical velocity from Sentinel-1 datasets and field observations.The results showed that immature land subsidence in the mentioned areas are growing slowly,which can be taken as a serious risk in future.展开更多
基金This work was supported by Research grant from Institute of Crustal Dynamics,China Earthquake Administration[grant numbers ZDJ2015-15 and ZDJ2013-22]National Natural Science Foundation of China[grant numbers 41104028 and 41204004]and the TerraSAR-X data we used were provided by the DLR in the frame of the General AO project LAN0208.
文摘Yangbajain contains the largest geothermal energy power station in China.Geothermal explorations in Yangbajain first started in 1976,and two plants were subsequently built in 1981 and 1986.A large amount of geothermal fluids have been extracted since then,leading to considerable surface subsidence around the geothermal fields.In this paper,InSAR time series analysis is applied to map the subsidence of the Yangbajain geothermal fields during the period from December 2011 to November 2012 using 16 senses of TerraSAR-X stripmap SAR images.In the case of the TerraSAR-X data,most orbital fringes were removed using precise orbits during the interferometric processing.However,residual orbital ramps remain in some interferograms due to the uncertainties in the TerraSAR-X orbits.To remove the residual orbital ramps,we estimated a best-fit‘twisted plane’for each epoch interferogram using quadratic polynomial models based on a network approach.This method removes most of the long-wavelength signals,including orbit ramps and atmospheric effects.The vertically stratified component(Topography Correlated Atmospheric Delay,TCAD)was also removed using a network approach.If the influence of seasonal frozen ground(SFG)is not taken into consideration,our results show that the subsidence rate around power plant I(the south plant)is approximately 20 mm/yr with a peak of 30 mm/yr.The subsidence rate around power plant II(the north plant)is approximately 10 mm/yr,when accounting for the influence of SFG on the power plant and its surrounding ground surface.Our results show that ground motion is caused by seasonal frozen ground and is strongly related to the temperature change.
基金funded by the TUBITAK#2221 project and the University of Tabriz,and the Japanese Society for the Promotion of Science(JSPS)Grants-in-Aid for Scientific Research(KAKENHI)grant number#23H01654。
文摘ABSTRACT Conducting long measurements of infrastructure deformation is a critical engineering task.Conventional methods are both timeconsuming and expensive,limiting their use for large-scale applica-tions.The synergy of synthetic aperture radar(SAR)and geographic information systems(GIS)offers a complementary approach.This study focuses on the feasibility of using time series analysis of L-band PALSAR-2 images to discover land displacements in Istanbul and Kocaeli,significant industrial and residential areas in Turkey.PALSAR-2 phase and intensity information were analyzed.For phase analysis,14 L-band images from 2014 to 2021 were taken into account.Small baseline subset(SBAS)analysis was performed using 44 pairs,and results of the velocity,coherence and back-scattering values are presented.Coherence of all pairs and their correlations were calculated.Principal Component Analysis(PCA)reduced the dimension of coherence pairs,enhancing feature extraction and the final geocoded velocity map revealed a fastest subsidence rate of−58 mm/yr and a mean subsidence of−20 mm/yr.These findings were confirmed through mean vertical velocity from Sentinel-1 datasets and field observations.The results showed that immature land subsidence in the mentioned areas are growing slowly,which can be taken as a serious risk in future.
