Summary Results are presented of the directions of magnetization for twentyeight sets of rocks collected from different parts of Japan. The directions for rocks of Pre‐Tertiary age from south‐west Japan differ systematically from those from north‐east Japan. It is suggested that the difference is due to the deformation of the Japanese Islands in the late Mesozoic or early Tertiary. Because of the deformation, it is not possible to infer the accurate position of the geomagnetic dipole with respect to Japan for Pre‐Tertiary times.

Synthetic aperture radar (SAR) is an effective means of monitoring land subsidence, and differential interferometric SAR (DInSAR) is commonly used to acquire the necessary data. In particular, persistent scatterer interferometry (PSI) can be used to measure land subsidence accurately over a wide area from multi-temporal SAR images. However, the estimated displacement is obtained only in the radar line-of-sight (LOS) direction, making it necessary to develop a method for measuring three-dimensional displacements by combining multidirectional observations. Therefore, we propose herein a method for estimating three-dimensional displacement velocities by combining the results from PSI and geodetic deformation measurements, namely, Global Positioning System and leveling data. We apply the least-squares method to Kansai International Airport in Japan by using 13 ALOS-2/PALSAR-2 ascending images from 2014 to 2018 and 17 ALOS-2/PALSAR-2 descending images from 2015 to 2018. In validation, the rootmean-square errors are 14, 16, and 14 mm/year for the east-west, north-south, and vertical components, respectively, showing that combining PSI results and geodetic deformation measurements is effective for monitoring land subsidence.

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