At 5:56 p.m. on October 23, 2004, a magnitude 6.8 earthquake occurred with its epicenter in the Chuetsu Region of Niigata Prefecture. It was named the 2004 Niigata-ken Chuetsu Earthquake by the Japan Meteorological Agency. This earthquake first recorded seismic intensity of 7, the highest on the Japanese seismic intensity scale, since the beginning of instrumental measurement of seismic intensity in Japan. With its epicenter in a mountainous region, it caused many slope failures and landslides, cutting off the road network at numerous locations. Immediately after the earthquake, the headquarters of the Ministry of Land, Infrastructure and Transport (MLIT) proclaimed an emergency status to cope with earthquake damage and established the MLIT Emergency Disaster Countermeasure Headquarters. The Hokuriku Regional Development Bureau (HRDB) of MLIT also proclaimed an emergency status for earthquake disaster and established the HRDB Disaster Countermeasure Headquarters. The MLIT Work Offices in and around Niigata Prefecture proclaimed necessary status ranging from emergency to advisory. With those statuses, MLIT devoted all of its resources to restoration so that all MLITdirectly administered national highways were reopened to general traffic by the second day after the earthquake except one tunnel, and normal traffic flow was ensured on all directly administered national highways by the 10th day after the earthquake. For the covering abstract see ITRD E139491.
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