09:00 〜 09:15
[J03-1-02] Postseismic deformation following the 1995 Kobe earthquake detected by space geodesy
A Mw 6.8 earthquake hit the city of Kobe, southwest Japan, and its surrounding area on January 17, 1995. The source faults, trending in the NE-SW direction, are estimated beneath the foothill of the Rokko Mountains, but it has a dominant right lateral strike slip components. The Rokko Mountains may have been built by the motion of active faults, but coseismic uplift may not be enough. There fore postseismic deformation might contribute to the building of the Rokko Mountains.
In order to study the postseismic deformation, we collected all available space geodetic data during about 20 years, including ERS-1/2, Envisat, JERS-1, ALOS/PALSAR and ALOS-2/PALSAR-2 images and continuous GPS data, and reanalyzed. Especially, temporal continuous GPS observation made by the Geographical Survey Institute, Japan in and around the Kobe area is important. We recalculated coordinates of these continuous GPS stations with recent PPP procedure using reanalyzed orbits and clocks of satellites.
Time series analysis of JERS-1 images revealed line-of-sight (LOS) decrease of the Rokko Mountains. PSInSAR results of ALOS/PALSAR also revealed slight uplift north of the Rokko Mountains. These observations suggest that the Rokko Mountains might have uplifted during the postseismic period.
LOS increase in a wedge shaped region between two active faults in the vicinity of the NE terminus of the source fault of the Kobe earthquake, which indicates that the subsidence between these two faults continued up to 2010. Continuous GPS observation during the first two years of the postseismic period shows north-south extension with right lateral motion between these two faults.
These observations suggest that the Rokko Mountains may have uplift till 2010. On the other hand, active faults near the NE terminus continued to slip with the formation of graben-like structure, due to coseismically loaded stress.
In order to study the postseismic deformation, we collected all available space geodetic data during about 20 years, including ERS-1/2, Envisat, JERS-1, ALOS/PALSAR and ALOS-2/PALSAR-2 images and continuous GPS data, and reanalyzed. Especially, temporal continuous GPS observation made by the Geographical Survey Institute, Japan in and around the Kobe area is important. We recalculated coordinates of these continuous GPS stations with recent PPP procedure using reanalyzed orbits and clocks of satellites.
Time series analysis of JERS-1 images revealed line-of-sight (LOS) decrease of the Rokko Mountains. PSInSAR results of ALOS/PALSAR also revealed slight uplift north of the Rokko Mountains. These observations suggest that the Rokko Mountains might have uplifted during the postseismic period.
LOS increase in a wedge shaped region between two active faults in the vicinity of the NE terminus of the source fault of the Kobe earthquake, which indicates that the subsidence between these two faults continued up to 2010. Continuous GPS observation during the first two years of the postseismic period shows north-south extension with right lateral motion between these two faults.
These observations suggest that the Rokko Mountains may have uplift till 2010. On the other hand, active faults near the NE terminus continued to slip with the formation of graben-like structure, due to coseismically loaded stress.