Hokkaido University Research Profiles

Arctic Research

Remote Sensing of Ground Deformation in the Arctic

Detection of surface subsidence associated with permafrost thawing

Images of ground deformation can be detected from data obtained by the Synthetic Aperture Radar (SAR) onboard the Daichi satellite. Conventionally, the main target has been ground surface displacement caused by earthquakes and volcanic activity, but detection of local ground deformation that is not associated with earthquakes or volcanoes in the permafrost regions of the Arctic Circle has also started.

Content of research

In the study of earthquakes and volcanic activity, the Earth's interior is sometimes estimated by capturing slight movement of the Earth's surface. This movement is called crustal movement, and efforts are still being made to improve the estimation accuracy and quality. Recently, interferometric SAR (SAR interferometry), which uses satellite SAR phase data, has made it possible to detect crustal movement in remote areas and overseas. In the Arctic, there is no so-called crustal movement, but as shown in the figure below, clear ground deformation has been detected in Western Siberia. This can be seen around so-called thermokarst terrain, which is often found in the Arctic, and is thought to represent subsidence of the ground surface due to the thawing of permafrost. Research on the formation process of thermokarst landforms, which has been largely untouched in the past, has just begun, and evaluation of the impact of global warming is an important issue for the future.

  • Google Earth image of the target area (left), InSAR image based on Daichi data on July 16, 2008 and July 19, 2009 (right) The purple parts in the white circle are deformed in a direction away from the satellite. This is thought to be ground deformation that occurred during this period.

Potential for social implementation

  • ・Monitoring landslide areas
  • ・Research of the effects of global warming on the Arctic
  • ・Underground fluid monitoring

Appealing points to industry and local governments

Permafrost is distributed over a wide area of the Siberian Plain, but it is too large to conduct a detailed dynamic survey by ground-based observation alone. InSAR ground motion mapping of the entire Siberian Plain is important to select meaningful land observation sites. We hope that a large amount of satellite data will become readily available for this purpose.