Geometry and the Mechanism of Landslide Occurrence in a Limestone Area – Case Examples of Landslides in Vietnam and from Europe, China, and Japan –

Landslide damage has been reported in many limestone areas in Europe, where the population lives close to limestone areas, and in Guilin in southern China and Ha Long in Vietnam, which are known for their unique limestone landscapes. There are few studies on the mechanism and type of landslide motion in and around such limestone areas. The lack of basic data is a problem for risk assessment and countermeasures in limestone areas. In this study, we summarized the causes and mechanisms of landslide occurrence, including geology and groundwater, focusing on six landslides that occurred in limestone areas in northern Vietnam, and classified them into six types of landslide movement. In the case of Japan, the occurrence of landslides in limestone areas is rare despite the wide distribution of limestone, and it is difficult to classify the type of movement. Differences in the landslide mechanisms are caused by the difference between limestones generated in the pelagic environment of Japan and limestones developed along the Tethys Sea coast, which are mixed with pelitic rocks as shallow-water sediments in Europe, China, and Vietnam. It is necessary to elucidate the relationship between landslides and the formation environment and sedimentary characteristics of limestone as an accretionary prism based on comparisons of a wide range of cases in future studies.