Land Subsidence in Xiong’an New Area,China Revealed by InSAR Observations

In 2017,China’s central government approved the national strategy to build Xiong’an New Area(XNA,100 km southwest to Beijing),which was announced as a"millennium strategy"and a"demo area"for a sustainable,modern,and innovative urban model.Xiong’an will draw in as much as$380 billion investment and is expected to help accelerate the development of the wider Beijing-Tianjin-Hebei(Jingjinji)Area.In this paper,present subsidence in the XNA area is investigated using InSAR observations for the first time.The 24 SAR images acquired by European Space Agency’s Sentinel-1 satellites during the period from June 2017 to July 2018 suggest that in the north of Xiong County,the subsidence rate reaches up to 90 mm/y,which is highly correlated with the exploitation of geothermal drilling.As the construction in the XNA area will significantly accelerate and its high-quality development,the InSAR findings could provide valuable information for future sustainable urban planning and underground infrastructure construction.

Local stress field inverted for a shale gas play based on focal mechanisms determined from the joint source scanning algorithm

The joint source scanning algorithm(SSA)scans locations and focal mechanisms of microseismic events simultaneously.Compared to the traditional source scanning algorithm,it yields much more events with extra information of focal mechanisms.The availability of more events and focal mechanisms make it possible to invert for a 2D gridded stress field.As a byproduct of hydrofracturing monitoring,the method offers a new way to extract stress field as a substitute to other more expensive technologies.This method is applied to a hydraulic fracturing dataset collected from one shale gas production field in the southeast of the Sichuan basin.A damped stress inversion is conducted to obtain a 2D stress field.five hydraulic-fracturing induced fractures can be determined from the result.The events associated with these fractures generally have relatively low stacked energy and are limited to the depth of horizontal well.One existing fault(possibly associated with the axis of the central Sichuan uplift)is also determined and the events associated with the existing fault generally have higher stacked energy and are more densely populated.The existing fault may also serve as a structural boundary where the rocks to the NW side are easier to be fractured while events on the other side are sparse with low stacked energy.The existing fault also divides the stress field into two regimes:the maximum compressional stress field to the NW and SE of the fault line are dominantly in NW-SE and N-S directions,respectively.

Ground infrastructure monitoring in coastal areas usingtime-series inSAR technology:the case study of Pudong International Airport,Shanghai

Shanghai Pudong International Airport(PDIA),with its east side built along the coast with weak geological conditions,is prone to uneven foundation settlement due to the consolidation and compression of soil and erosion of coastal tides,affecting the safe operation of the airport.Therefore,it is crucial to conduct dynamic subsidence monitoring within the airport,especially in the runway area.29 scenes of ascending track Sentinel-1A radar images from August 2016 to June 2018 are selected to perform surface deformation inversion based on PS-InSAR and improved SBAS-InSAR for PDIA and its around coastal area.Through cross-validation,the reliability of the time-series InSAR technique for dynamic monitoring of surface deformation of coastal zone infrastructures is confirmed.The results show severely uneven settlement.By combining the monitoring results with the local geological and hydrological dataset,the driving factors of differential deformation of the infrastructures are analyzed,including stratigraphic geological conditions,ground loadings,foundation treatment methods,water erosion,and groundwater level changes.Finally,the time-series deformation characteristics and the causes of PDIA’s runway are emphasized based on the PS deformation results.This case provides a reference for the safety management of critical infrastructure in coastal areas using advanced InSAR technique.