Landslides on ancient embankments in the Kinki district (Japan): Strong motion seismoscope of the 1596 Keichou-Fushimi earthquake

Abstract

Landslides on ancient embankments, burial mounds of Imashiro-zuka and Nishimotome-zuka, induced by historical earthquakes related to the tectonic movement of active fault systems located between northern Osaka and Kobe, are discussed. The geological conditions of the foundation of the mounds, the lithology, stiffness, and the position of the mound relative to the fault systems, contributed to the collapse of the mounds. Obvious interior structures of landslides revealed the inherent deformation process, and provided significant insight into landslide mechanisms. Rapid increasing pore water pressure was necessary to facilitate sliding along the almost horizontal slip surfaces developed in the main part of the landslide bodies on the Imashiro-zuka mound. Liquefaction analysis using both the results of dynamic triaxial compression tests and earthquake response analysis showed liquefaction in the foundation of the mound was a possible landslide mechanism on the Nishimotome-zuka mound. Landslides of embankments are unavoidable over long periods of time if any weaknesses are present at the foundation of the construction. The total quality of an artificial soil structure very much depends on the conditions of its foundation bed. Today, these ancient burial mounds in the Kinki district are located in both rural and urban regions, and landslides on these mounds provide unique information about issues related to the long-term stability of modern large-scale construction activities.