Reconnaissance Report of July 16, 2007 Niigata-Ken Chuetsu-Oki, Japan, Earthquake

The damage survey of the Niigata-ken Chuetsu-Oki, Japan earthquake (MJMA = 6.8) of July 16, 2007 was conducted by the reconnaissance team of Disaster Prevention Research Institute (DPRI), Kyoto university. The area with dimension of 24 km x 19 km is investigated by the reconnaissance team. This paper reports the seismological aspects and observed geotechnical and structural damage during the damage survey in the area. The landslides, liquefaction and ground settlements were the most important geotechnical features that caused serious damage to the lifelines and buildings. Especially, landslides caused major damage to the railways and roads. The building damage survey was conducted around Kashiwazaki city hall where the K-net strong motion station was located. The damage to the buildings was classified as D2 or D3 within 100m around the city hall. Meanwhile, the collapsed wooden houses (D6 Grade) were mostly concentrated in Higashi Honmachi street situated in 280 m south of city hall. Most of the wooden house, concrete block fences and tomb stones seem to have collapsed in the northwest-southeast direction falling to the east as to the west. This direction was found to be in the direction of slip on the fault.