Abstract
The landslide observation system has been operating at the Hiramaru landslide area since 1988. The system consists of the ground electric potential meters, the tiltmeters, the groundwater gauges, and the rain gauge. The method of observation is carrying out remote sensing in Nigata city of 100km distance from Hiramuru landslide area.
It was discussed in another paper for the effect of streaming potential caused by interflow in rainy day, the effect of streaming potential caused by flow of groundwater and the complex effects of potential caused by rainfall and changes of groundwater level.
This paper is described the effect of potential resulted from tilting motion at the slope without causes of rainfalls and the effect of potential as precursor of earthquake swarm at a distance of 30km apart from the observation system.
And, as a result of analyses of behavior of the ground electric potential and the groundwater level, the tilting motion at the slope of landslide area is concluded due to the collapse of aquifer in the slope. The collapse of aquifer is supposed to be long-standing eluviation of soil.
