The author compared the Persistent Scatterer Interferometry (PSI) results of different radar wavelengths; L- and C-band. The density of identified Persistent Scatterer (PS) points depends on the spatial resolution of the data in urban areas. In addition, L-band is capable of finding out PS points in vegetated area, while C-band is not. Measurement errors of individual PS points are 8-11 mm for L-band and 2-3 mm for C-band, almost proportional to the wavelengths. This suggests that the shorter wavelength is more suitable for pointwise usage such as infrastructure monitoring. Measurement errors of spatially averaged 30 PS points are 4-6 mm and about 2 mm/yr, being independent of wavelength, according to the comparison with continuous GNSS observation results. This means that L-band has a comparable capability of detecting spatially distributed deformation to C-band.
Here we compare the free-air gravity anomaly model by the GRAIL (Gravity Recovery and Interior Laboratory) mission and the topographic model from the LRO (Lunar Reconnaissance Orbiter) laser altimetry. They showed a high correlation up to degree/order ～400. The gravity-topography admittance showed typical behaviors, i.e. it is low for degree/order below 50 (i.e. wavelengths longer than ～220 km), increased sharply, and kept constant at ～110 mgal/km. Such a wavelength dependence provides the information on the thickness of the surface elastic layer ﬂoating on ductile lower layer. We estimated the elastic thick-ness of the Moon to be ～14 km. This thickness is not signiﬁcantly different from those found in the present Earth in spite of the smaller dimension of the Moon. This may suggest that the significant portion of the topographic features on the Moon was formed in the early ages of the Moon, when the heat ﬂow was comparable to the present Earth.