The fluctuation phenomena of ground water level and pressure were observed with two types of piezometer (quasi-Cassagrande type and electrical diaphragm type) installed at various depths (1-15m) at Naguki landslide area, Nagano Prefecture.
The fluctuations recorded by each piezometer can be divided into two elements-trends and short periodic fluctuations discussed in this report-by the arithmetic moving average method. All periodic fluctuations are classified into the fluctuation caused by precipitation and the fluctuation caused by atmospheric changes. It is assumed that the former is a property of ground water flow through large pores and cracks of the landslide soils and that the latter is a property of soil water in the aquiclude consisting of elastic landslide soil.
The ratio of pore pressure caused by atmospheric changes in the elastic aquiclude to atmospheric changes, elastic moduli of the soils, effective stresses and volume changes forced in the soils by atmospheric changes are discussed refering to those values obtained by other writers. ^{(6) (7)}
The effect of fluctuation phenomena on landslide movements, the setup of piezometric installations and other problems are discussed in this paper.

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Fluctuation of land surface has been observed by setting the observation poles at distances of 15 to 25 m. Thermal distribution at the 1-m depth under the ground surface has been also measured by thermistors. Their relation and their annual change are considered.
Extension of the land surface is found in the zones marked with X, Y and Z, and there are recognized transferences in the upper (southern) and lateral (western) direction (shown) with arrows in figure 2
Areas of high temperature over 60°C are distributed in the zones of 0, P, Q, Q', R, R' and S. It is observed that except those of R' and S the zones have moved gradually since 1963 when the survey was started. The southern parts of the zones of Q and Q' have moved toward the upper (southern) parts of slopes with 20°C-30°C. The zones of O and P have expanded or moved along the fault running from the north to the south. Due to these movements the zones with change have expanded gradually causing an increase of the instability of the slopes.
Figure 5 shows the zones where remarkable extension and high temperature are combined, as follows:
a) the zones of steep slope (xP and xQ zones)
b) the zones of gentle or almost flat slope (yQ' and yQ zones).
The latter phenomena may be closely related with landslide movement in the area concerned.

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