Coseismic Stress Changes, Landslides in the 2004 Mid-Niigata Prefecture Earthquake, and Their Impact on Post-quake Rehabilitations

Abstract The impact of a large inland earthquake is profound because of its intense shakes and the associated landslides and debris flows. The quake-induced landslides and debris flow are often the most devastating secondary effect of an earthquake in terms of all kinds of losses, causing long-lasting problems in post-quake rehabilitation activities. An earthquake-induced landslide is just one scene of ever-evolving mountain topography. Therefore, studying terrain dynamics is vital to comprehend the possibility of hazards and propose and apply rational rehabilitation tactics. Though serious, the damage caused by the Mid-Niigata Prefecture Earthquake of October 23, 2004, has given us a rare opportunity to study the landform changes caused by an earthquake that hit an active-folding mountainous terrain. To deal with rehabilitation problems in a scientific manner, a research program, “Earthquake damage in active-folding areas: the creation of a comprehensive data archive and suggestions for its application to remedial measures for civil-infrastructure systems,” was set up getting the Special Coordination Funds for Promoting Science and Technology, Ministry of Education, Culture, Sports, Science and Technology (MEXT). This article reviews some significant findings obtained through this project and even beyond it. The results show that essential aspects of quake-caused problems were linked to deep-seated tectonic displacements, namely the internal driving stress field associated with earthquakes to evolve the active-folding terrain.