Tohoku, Japan, Earthquake and Tsunami of 2011

Sponsored by the Structural Engineering Institute of ASCE.

On March 11, 2011, at 2:46 p.m. local time, the Great East Japan Earthquake with moment magnitude 9.0 generated a tsunami of unprecedented height and spatial extent along the northeast coast of the main island of Honshu. The Japanese government estimated that more than 250,000 buildings either collapsed or partially collapsed predominantly from the tsunami. The tsunami spread destruction inland for several kilometers, inundating an area of 525 square kilometers, or 207 square miles.

About a month after the tsunami, ASCE's Structural Engineering Institute sent a Tsunami Reconnaissance Team to Tohoku, Japan, to investigate and document the performance of buildings and other structures affected by the tsunami. For more than two weeks, the team examined nearly every town and city that suffered significant tsunami damage, focusing on buildings, bridges, and coastal protective structures within the inundation zone along the northeast coast region of Honshu.

This report presents the sequence of tsunami warning and evacuation, tsunami flow velocities, and debris loading. The authors describe the performance, types of failure, and scour effects for a variety of structures:

• buildings, including low-rise and residential structures
• railway and roadway bridges
• seawalls and tsunami barriers
• breakwaters
• piers, quays, and wharves
• storage tanks, towers, and cranes.

Additional chapters analyze failure modes utilizing detailed field data collection and describe economic impacts and initial recovery efforts. Each chapter is plentifully illustrated with photographs and contains a summary of findings.

For structural engineers, the observations and analysis in this report provide critical information for designing buildings, bridges, and other structures that can withstand the effects of tsunami inundation.