Abstract
The method of marking or of quantification has been so far proposed as a method for estimating the possibility of boulder-fall on a slope. The former is of very practical use but has little statistical background, while the latter bases on statistics but is not serviceable on account of its complicated procedure. In this report, a hybrid method is developed by accepting the merits of the two methods. The superiority of the hybrid method is shown by comparing with the methods of marking proposed in the past and by applying to practical problems.
