We applied differential InSAR analysis to the Shiretoko Peninsula, northeastern Hokkaido, Japan. All the interferograms of long temporal baseline (~ 3 years) processed from SAR data of three L-band satellites (JERS-1, ALOS, ALOS-2) commonly indicate remarkable phase changes due to the landslide movement at the southeastern flank of Mt. Onnebetsu-dake, a Quaternary stratovolcano. The area of interferometric phase change matches to known landslide morphologies. Judging from the timing of the SAR image acquisitions, this landslide has been moving at least from 1993 to the present. Successive interferograms of 1-year temporal baseline indicate the temporal fluctuation of the landslide velocity. Especially for the descending interferograms, the positive line-of-sight (LOS) length change, which indicates large subsidence relative to the horizontal movement, is observed in the upslope section of the landslide during 1993–1998, while the negative LOS change is observed in the middle and the downslope section after 2007 indicating less subsidence. The landslide activity culminates from 2014 to 2017: the eastward and the vertical displacement rates reach ~ 6 and ~ 2 cm/yr, respectively. Utilizing high spatial resolution of ALOS and ALOS-2 data, we investigated velocity distribution inside the landslide. During 2007–2010, the eastward component of surface displacement increases toward the east, implying that the landslide extends toward the east. During 2014–2017, the vertical displacement profile exhibits spatially periodic uplift and subsidence consistent with surface gradient, which indicates the ongoing deformation driven by gravitational force. Heavy rainfall associated with three typhoons in August 2016 might have brought about an increase in the landslide velocity, possibly due to elevated pore-fluid pressure within and/or at the base of the landslide material. Also, annual rainfall would be an important factor that prescribes the landslide velocity averaged over 3 years.

中文翻译：

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Mt. 大型滑坡的时空行为。日本 Onnebetsu-dake，由三颗 L 波段 SAR 卫星探测到

我们将差分 InSAR 分析应用于日本北海道东北部的知床半岛。由三颗 L 波段卫星（JERS-1、ALOS、ALOS-2）的 SAR 数据处理的长时间基线（~3 年）的所有干涉图通常表明由于山东南侧的滑坡运动引起的显着相位变化。Onnebetsu-dake，第四纪层状火山。干涉相变区域与已知的滑坡形态相匹配。从SAR图像采集的时间来看，该滑坡至少从1993年到现在一直在移动。1 年时间基线的连续干涉图表明滑坡速度的时间波动。特别是对于下降干涉图，正视距（LOS）长度变化，1993-1998 年间在滑坡的上坡段观察到相对于水平移动较大的下沉，而在 2007 年之后在中部和下坡段观察到负的 LOS 变化表明下沉较少。滑坡活动在 2014 年至 2017 年达到高潮：向东和垂直位移速率分别达到 ~ 6 和 ~ 2 cm/yr。利用 ALOS 和 ALOS-2 数据的高空间分辨率，我们调查了滑坡内部的速度分布。2007-2010 年，地表位移的东向分量向东增加，表明滑坡向东延伸。2014-2017 年，垂直位移剖面呈现出与地表梯度一致的空间周期性抬升和沉降，这表明由重力驱动的持续变形。2016 年 8 月与三场台风相关的强降雨可能导致滑坡速度增加，这可能是由于滑坡材料内部和/或底部的孔隙流体压力升高。此外，年降雨量将是规定 3 年平均滑坡速度的重要因素。