Nationwide urban ground deformation monitoring in Japan using Sentinel-1 LiCSAR products and LiCSBAS

Abstract

Ground subsidence in urban areas is a significant problem because it increases flood risk, damages buildings and infrastructure, and results in economic loss. Continual monitoring of ground deformation is important for early detection, mechanism understanding, countermeasure implementation, and deformation prediction. The Sentinel-1 satellite constellation has globally and freely provided frequent and abundant SAR data and enabled nationwide deformation monitoring through InSAR time series analysis. LiCSAR, an automatic Sentinel-1 interferometric processing system, has produced abundant interferograms with global coverage, and the products are freely accessible and downloadable through a web portal. LiCSBAS, an open source InSAR time series analysis package integrated with LiCSAR, enables users to obtain the deformation time series easily and quickly. In this study, spatially and temporally detailed deformation time series and velocities from the LiCSAR products using LiCSBAS for 73 major urban areas in Japan during 2014–2020 were derived. All LiCSBAS processing was automatically performed using predefined parameters. Many deformation signals with various temporal and spatial features, such as linear subsidence in Hirosaki, Kujyukuri, Niigata, and Kanazawa, episodic subsidence in Sanjo, annual vertical fluctuation in Hirosaki, Yamagata, Yonezawa, Ojiya, and Nogi, and linear uplift in Chofu were detected. Unknown small nonlinear uplift signals were found in Nara and Osaka in 2018. Complex postseismic deformations from the 2016 Kumamoto earthquake were also revealed. All the deformation data obtained in this study are available on an open repository and are expected to be used for further research, investigation, or interpretation. This nationwide monitoring approach using the LiCSAR products and LiCSBAS is easy to implement and applicable to other areas worldwide.

The challenge to use multi-temporal InSAR for landslide early warning

“…This is not necessarily the case and may lead to erroneous conclusions. Consequently, following earlier work by Berti et al (2013), the analysis of non-linear deformation patterns has attracted increasing attention recently (Park and Hong 2021;Morishita 2021;Schlögl et al 2021;Reinosch et al 2020). Note that this is closely interconnected with the development of warning thresholds, whose definition is naturally also dependent on the (expected) type of deformation pattern.…”

Reply on CC1

“…The dataset used for this study is collected from European Space Agency (ESA), via the Copernicus Open Access portal, and from the Alaska Satellite Facility (ASF DAAC). The C-band Sentinel-1 A and B, launched in 2014 and 2016 respectively, provide regular data sets (Morishita, 2021). For the InSAR use, the Interferometric Wide (IW) swath Single Look Complex (SLC) data is selected and processed with the open-source software SNAP (Sentinel Applications Platform).…”

“…It is able to generate maps of mean velocity displacement and deformation time series for all processed frames. Furthermore, it is easy to implement and does not request high-performance computing facilities (Morishita, 2021).…”

“…The LiCSAR system automatically processes Sentinel-1 InSAR datasets (Lazeckỳ et al, 2020b), to generate wrapped, unwrapped interferograms and coherence maps (Lazeckỳ et al, 2020b), with a final product resolution of ~26.5 m (Lazeckỳ et al, 2020a). LiCSBAS exploits the data of LiCSAR in order to generate maps of displacement mean velocity and deformation time series plots (Morishita, 2021).…”

A New Set of Tools for the Generation of InSAR Visibility Maps over Wide Areas

“…The regular six day acquisition plan combined with the free and open data policy makes the radar images acquired by this sensor the best solution for significantly widening the range of MTInSAR applications [9][10][11]. The data volume offered by Sentinel-1, together with the consolidation of processing algorithms and the increasing computational capacity of processing units paved the way for the design and set up of nationwide Ground Motion Services (GMS) [12][13][14][15][16][17][18] and satellite-based operational monitoring services [19][20][21][22].…”