6:15 PM - 7:30 PM
[HDS06-P07] Detection of Landslide displacement by Geodetic techniques at the Noto Peninsula
Keywords:Landslide displacement, geodetic techniques, GPS, InSAR, Noto Peninsula
In this study, we estimated landslide displacements by geodetic techniques and analyzed the characteristic of landslide movement with ground surface observations at Wajima City, Ishikawa Prefecture, in the Noto Peninsula. We conducted GPS observations of the landslide during July 2014 to March 2015, and detected ground surface displacements from a change in the positions of the GPS sites. We also conducted SAR (synthetic aperture radar) analyses of InSAR (SAR interferometory) and PS-InSAR (persistent scatterer SAR interferometry) using 10 ALOS/PALSAR images acquired from December 2006 to October 2010. Furthermore, we used the ground data observation records of the borehole extensometers obtained by the Ishikawa Prefecture from 2008 to the present. We examined a landslide history of the analyzed area by tracking a topographic map published in 1970 and 5 m DEM released by GSI (Geospatial Information Authority of Japan) recently.
The InSAR analysis reveals landslide displacements of several tens cm/year in the area of 500 m x 500 m and horizontal displacements of 0.6-1.0 cm/year are estimated from GPS. The magnitudes and directions of the landslide displacements are coincident with the monitoring result of the borehole measurements and previous researches. We estimate the average rate of the landslide displacements of 0.5-0.8 m/year from the tracking topographical characteristics using the topographic data. These observations confirm that the landslides in the analyzed area have been active in recent years and suggest that active landslides in the past forms distinct scarp terrains and causes the past disasters written in historical materials.
Acknowledgements: PALSAR data are shared among PIXEL (PALSAR Interferometry Consortium to Study our Evolving Land surface), and provided from JAXA (Japan Aerospace Exploration Agency) under a cooperative research contract with ERI (Earthquake Research Institute, the University of Tokyo). The ownership of PALSAR data belongs to METI (Ministry of Economy, Trade and Industry) and JAXA. We would like to thank for the use SIGMA-SAR software for InSAR analysis [M.Shimada, 1999], StaMPS software for PS-InSAR analysis [Hooper et al., 2004, 2007], DEM (Digital Elevation Model) by GSI using SAR analysis, and GMT (Generic Mapping Tools) [Wessel,P. and W.H.F.Smith, 1998] and QGIS software to draw the result.