Conference Agenda

Geohazard monitoring is essential to anticipate and alleviate the hazards of natural disasters, safeguard human lives and critical infrastructure, and promote the sustainable growth of communities located in areas prone to such events. The increasing incidence of land subsidence and landslides poses a significant threat to human settlements and critical infrastructure worldwide, requiring urgent attention and mitigation measures. To effectively manage the risks associated with geohazards and minimize their impacts, it is of utmost importance to map their displacement rates and gain a comprehensive understanding of their mechanics. In this work, the main outcomes relevant to the joint European Space Agency (ESA) and the Chinese Ministry of Science and Technology (MOST) Dragon-5 initiative cooperation project ID 59339 “Earth observation for seismic hazard assessment and landslide early warning system” are reported. During last year, the research team has been mainly working on: a) EO monitoring, automatic mapping and classification of active displacement areas related to land subsidence and landslides on wide regions; and b) identification of triggering factors and modelling of specific landslides and land subsidence based on InSAR and in situ data. The results obtained from the study, which primarily concentrate on selected vulnerable areas in China and Spain, offer valuable insights for planning current and future scientific efforts aimed at monitoring landslides and land subsidence. The comprehensive analyses of these geohazards are essential for effective prevention and management, as well as enabling prompt response in the aftermath of their occurrence.

In the framework of the ESA-MOST Dragon-5 project, the National Institute of Geophysics and Volcanology (INGV) from Italy, Northeastern University (NEU) and Jilin Earthquake Agency from China conduct collaborative research on the multiple mining-induced geohazards in Northeast China using time Series SAR images. Moreover, we have also considered a new study site, the Changbaishan active volcano (Jilin Province, ~300 km east from Shenyang), which was responsible for the largest eruption of the last millennium in 946 CE.

Our first study site is the Fushun west Opencast coal mine (FWOCM), located in the southwest of Fushun city, China, which is the largest opencast mine in Asia. Since the 1920s, more than 90 landslides have been reported in FWOCM, especially the huge landslide on the south slope, which named Qiantaishan landslide. The Qiantaishan landslide has experienced a fast moving period during 2013 to 2016, and has stabilized since 2017. During the fast moving period, the landslide mass has moved approximately 90 m. However, since 2017, displacements of the Qiantaishan landslide is less than 150 mm/year. In order to analyze the spatial pattern and temporal evolution of different periods of the Qiantaishan landslide, both MT-InSAR and multi-temporal pixel offset tracking have been performed. Multi-temporal pixel offset tracking has been conducted considering 53 Cosmo SkyMed SAR images collected from 2013-07-03 to 2016-12-18 for the descending track, to monitor displacement of the fast moving period of Qiantaishan landslide. The results show that the landslide moves very fast during 2014, and slows down during 2015 to 2016. The MT-InSAR analysis has been carried out based on Sentinel-1 images collected during 2017 to 2022, to track the slow-moving period of Qiantaishan landslide. MT-InSAR results highlight that the displacements rate of the Qiantaishan landslide is up to 150 mm/year, which has basically stabilized. Comparison with ground measurements and cross correlation analysis via cross wavelet transform with monthly precipitation data are also computed, to analyze the influence factors of displacements in FWOCM.

The second study site, Changbaishan volcano complex is affected by landslides, earthquakes, degassing, and ground deformation. Deformations occurred during the 2002-2006 unrest episode and in 2020-2022. Analysis on the multi-hazards of Changbaishan is very important because a population of ~135000 in China and 31000 in North Korea lives within 50 km far from the volcano. Using 33 Envisat ASAR images acquired during 2004-2010 along the descending orbit, the accurate surface deformation parameters of Changbaishan Tianchi volcano has been extracted through a modified multi-temporal InSAR approach which involves point selection based on the Normalized Difference Vegetation Index (NDVI), to minimize the volume decorrelation problem. Then, based on three-dimensional geometric relationship between the volcanic surface deformation field and the radar line of sight (LOS) deformation, Mogi point source modeling has been calculated, revealing the inflation-deflation-stabilization process of the magma chamber during the end of the 2002-2005 unrest episode. Furthermore, we analyze the deformation of Changbaishan volcano during 2018–2022 processing by means of the SBAS technique a dataset consisting of 23 ALOS-2 images (L-Band, StripMap mode), acquired along the ascending orbit and revealing a low-level unrest occurred during 2020.12-2021.6. Modeling results suggest that three active sources are responsible for the observed ground velocities: a deep tabular deflating source, a shallower inflating NW-SE elongated spheroid source, and a NW-SE striking dip-slip fault. The depth and geometry of the inferred sources are consistent with independent petrological and geophysical data.

Acknowledgments

The Sentinel-1 data are free of charge distributed by the European Space Agency.

The COSMO-SkyMed data are provided by ASI through the ASI-ESA Dragon5 Project ID. 58029.