Abstract
In spite of use of a strain gauge pipe, we can't always find a slip surface of landslides successfully. One of these causes is due to the interval of gauges. By using the equation of Chang, the interval of gauges can be decided. The authers discuss the interval of gauges for each type of landslides; clays slide, debris slide, weathering rock slide, rock slide. For example the gauges should be put on the surface of a vinyl chloride pipe at the interval of less than 90 cm for the type of clays slide, and for weathering rock slide at a space of at least 45cm.
