| Titre : |
Coverage of the Taiwan island by InSAR with Sentinel-1 and ALOS images |
| Type de document : |
Article/Communication |
| Auteurs : |
Bénédicte Fruneau  , Auteur ; Erwan Pathier, Auteur ; Marie-Pierre Doin, Auteur ; Jyr-Ching Hu, Auteur ; Hsin Tung, Auteur |
| Editeur : |
Champs/Marne : Université Paris-Est Marne-la-Vallée UPEM |
| Année de publication : |
2019 |
| Conférence : | LPS 2019, ESA Living Planet Symposium 13/05/2019 17/05/2019 Milan Italie programme sans actes | | Langues : |
Français (fre) |
| Descripteur : |
[Vedettes matières IGN] Traitement d'image radar et applications
[Termes descripteurs IGN] image ALOS-PALSAR
[Termes descripteurs IGN] image Sentinel-SAR
[Termes descripteurs IGN] interféromètrie par radar à antenne synthétique
[Termes descripteurs IGN] surveillance géologique
[Termes descripteurs IGN] Taïwan
|
| Résumé : |
(auteur) Taiwan Island, resulting from oblique collision between Philippine sea plate and Eurasian plate converging at a rate of about 8 cm per year, is one of the most active tectonic region in the world. With a subtropical environment, it is faced to different hazards, including earthquakes, debris flow, landslides, and flooding. The precise measurement of the present-day ground displacements at the scale of the whole Taiwan Island is thus essential in several domains of Earth Sciences, in particular for earthquake cycle study and earthquake hazard assessment, for subsidence and landslide monitoring, and also to better understand the kinematics and mechanics of mountain building. Taiwan benefits from a remarkable GNSS network. However, due to a complex geodynamical context and high strain rate, the pattern of deformation is not well solved by GNSS. In complement, INSAR shows its contribution with respect to GNSS, as it allows to dramatically increase the spatial information. Combining SAR dataset provided by ALOS-1, ALOS-2 and Sentinel-1 enables to generate consistent time series and dense maps of ground displacements by InSAR on the whole island over different periods. This possibility of long time series of observations is particularly interesting for earthquake cycle study.
Our processing uses NSBAS interferometric chain (Doin et al., 2015), based on a SBAS approach, that includes several corrections applied before unwrapping, in particular correction of atmospheric delays predicted from the global atmospheric re-analysis ERA-Interim model, and local DEM error correction. These corrections are of particular importance as they reduce the variance of the phase across regions with high topographic gradients, like the Central Range in Taiwan, hence facilitating unwrapping step. Using the full archive of ALOS-1 PALSAR images, a first complete deformation map of Taiwan has been derived over the period 2007-2011. Our InSAR results offer an unprecedented continuous view of deformation field of the entire Island. For instance, in the Central Range, the LOS velocity map shows a clear pattern of deformation, consistent with a rapid uplift (cm/y) of the Central Range South of the island. This uplift, already partially documented by GPS and leveling, is clearly mapped here and seems to show an overall continuity. In southwestern Taiwan, the InSAR LOS velocity map provides a good coverage in the foothills area, revealing several localized areas of interseismic deformation that were overlooked in GNSS, and that can be correlated with tectonic structures. Among them, is the 15 km-long Lungchuan anticline, showing relative surface displacement toward satellite by several cm/year. Those observations, combined with a geological study and field survey (Le Beon et al., 2017), suggest the existence of a back-thrust fault that reaches the surface on western side of Lungchuan ridge and roots on the ~4 km deep Tainan detachment. This structure has also been activated during 2010 Mw 6.3 Jia-Shian Earthquake and the Meinong earthquake (02/05/2016, Mw6.4). A time series analysis can also be conducted on 2014-2018 period with Sentinel-1 data. Since end of 2014, we benefit from S1 SAR images, acquired in C-band, thus less favorable than PALSAR L-band on Taiwan Island. However, this drawback is balanced thanks to the high frequency of image acquisitions (12 days on Taiwan with S1-A and S1-B). We can also take advantage of the 2 different geometries of acquisition (both ascending and descending) to derive horizontal and vertical components of the deformation. The combination of ALOS and Sentinel-1 InSAR results, in addition to their high density of measure, covers different time periods and gives the opportunity to investigate temporal evolution of the deformation. Some areas, in particular in SW Taiwan, show changes in the tectonic deformation pattern, thus revealing transient behavior of some structures. Those observations can also be completed on several areas with previous ERS and Envisat INSAR results, offering an unique monitoring of more than 20 years. |
| Numéro de notice : |
C2019-055 |
| Affiliation des auteurs : |
LaSTIG+Ext (2016-2019) |
| Thématique : |
IMAGERIE |
| Nature : |
Poster |
| nature-HAL : |
ComSansActesPubliés-Unpublished |
| DOI : |
sans |
| En ligne : |
https://lps19.esa.int/NikalWebsitePortal/living-planet-symposium-2019/lps19/Agen [...] |
| Format de la ressource électronique : |
vers le résumé |
| Permalink : |
https://documentation.ensg.eu/index.php?lvl=notice_display&id=96644 |
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