A review of landslide hazards in Japan and assessment of their susceptibility using an analytical hierarchic process (AHP) method

Abstract

In spite of its small size, Japan suffers many landslide disasters due to intense rainfall and earthquakes. This article describes the distribution and topography of these landslides, and a new method of evaluating the susceptibility, the analytical hierarchic process (AHP). The method assigns scores to each factor of micro-topography of landslide-prone areas identified in aerial photographs, and assesses the susceptibility of landslide from the total score. In addition, a method of simulating sliding mass runout is briefly presented for the designating sediment-related disaster warning areas. Types and damage situation of sediment-related disasters in JapanKinds and classification of sediment-related disasters Japan has a total land area of 370,000 km 2 , of which 70% is mountainous. Although this is only 0.1% of the earth's land area, over 10% of all active volcanoes (86) are located in Japan, and the country accounts for about 10% of the world's seismic energy emission. In addition, Japan receives annual precipitation of 1750 mm, which is almost double the annual global average, and is struck by approximately 11 typhoons every year. Thus, the country is prone to sediment-related disasters.Sediment-related disasters in Japan vary in morphology depending on whether caused by rainfall, snow melt, earthquake, soil, geological structure, topography, or other factors. Sediment-related disasters can be classified either legally or academically. The legal classification is: debris flow, landslide and slope failure, based on differences in damage features, investigation methods and prevention countermeasures. This classification is based on the fact that Japanese people have long distinguished between "flow", "slide" and "collapse" of earth masses according to the speed of travel, distance traveled, size and physical properties of traveling soil mass, possibility of recurrence, and other traveling morphologies. Landslides and slope failures are distinguished as shown in Table 1.Sediment-related disasters are classified according to this table by engineers of governmental bodies, and prevention and evacuation measures are taken based on the Landslide Prevention Law and the Law for Prevention of Steep Slope Failure Disaster. Municipal governments then inform local residents of the landslide-risk areas identified. Academically, the classification by Varnes (1978) is used. States and characteristics of sediment-related disastersThe frequency of sediment-related disasters is affected by the occurrence, scale, and intensity of triggers, such as earthquakes, volcanic activity, storms, and snow melting. Sediment-related disasters have been more frequent in recent years probably due to abnormal local downpours, which may be attributable to global warming, and frequent earthquakes such as the large shallow direct-hit earthquake in Niigata-Chuetsu (M=6.8) in 2004. Recent sediment-related disasters have also tended to affect city residents possibly due to residential development in mountainous areas, and some large-scale debris fl...

Urgent landslide susceptibility assessment in the 2013 Lushan earthquake-impacted area, Sichuan Province, China

“…Finally, the weight of the importance degree of various factors can be obtained, which provide basis for the choice of the best available solutions (Saaty 1997). So far, the AHP method has been widely used to landslide study (Tang et al 2011a;Yoshimatsu and Abe 2006;Kamp et al 2008). In our study, the AHP method was used to determine the factor weights, which indicate the importance degree of causative factors to landslide occurrence.…”

“…Qualitative methods mainly refer to site analysis and overlay analysis of thematic maps (for example, geomorphological and geological characteristics) based on expert experience (Anbalagan and Singh 1996;Ayalew et al 2004). Quantitative methods mainly refer to various statistical analyses (Carrara et al 1991;Tang et al 2011a;Yoshimatsu and Abe 2006;Kamp et al 2008), such as artificial neural network (ANN) (Lee and Evangelista 2006;Yilmaz 2010), support vector machine (SVM) (Yao et al 2008;Yilmaz 2010;Xu et al 2012), Bayesian Network (Song et al 2012) and Logistic Regression (Dong et al 2011;Nefeslioglu et al 2006;Xu et al 2013a, b). These methods have different characteristics and adaptability for various environmental conditions of different regions (Tangestani 2009;Mohammady et al 2012;Ozdemir and Altural 2013).…”

A risk analysis for floods and lahars: case study in the Cordillera Central of Colombia

“…Despite this importance, there has been little research into methods of weighting and standardization of indicators for disaster risk analysis so far. Castellanos Abella and van Westen (2007) applied multi-criteria evaluation techniques, while Komac (2006) and Yoshimatsu and Abe (2006) applied analytical hierarchical process methods, yet restricted to landslide susceptibility. The process of weighting vulnerability indicators involves the political and societal level and thus goes beyond scientific responsibility and thus should be undertaken in discussion with public authorities.…”

Scale and spatial distribution assessment of rainfall-induced landslides along mountain roads

“…Many studies have evaluated slope conditions based on an understanding of regional slope stability; researchers have considered the influence of landslides on the surrounding environment and have established methods of evaluating regional 15 landslide susceptibility assessment models (Yoshimatsu and Abe, 2006;Romeo et al, 2006;Van Westen et al, 2006). The methods used to analyze slope stability in previous studies can be broadly divided into two categories: topographical methods and engineering methods (Hansen, 1984).…”

“…In this type of landslide susceptibility analysis, causal factors are collected and analyzed qualitatively or 20 quantitatively. Regarding landslide evaluation, Yoshimatsu and Abe (2006) used the analytic hierarchy process (AHP) to assess landslide susceptibility in hazardous areas in Japan. In addition to using aerial photos to identify microlandform factors and areas with landslide potential, the researchers employed the AHP to issue scores and then used the total scores to determine landslide sensitivity.…”