Title:
Lessons Learned From the 2011 Tohoku, Japan, Earthquake
Author(s):
Shunsuke Otani
Publication:
Symposium Paper
Volume:
296
Issue:
Appears on pages(s):
1-20
Keywords:
Earthquake, Damage, Non-structural Elements, Reinforced concrete buildings, Seismic design, Seismic retrofit, Seismology, Tsunami
DOI:
10.14359/51686885
Date:
3/6/2014
Abstract:
The 2011 off the Pacific coast, Tohoku Earthquake (Mw=9.0) was the largest in the history of seismic observation in Japan. Seismology research community did not anticipate the possible occurrence of such a mega earthquake in the area. Main casualties were caused by tsunamis rather than by the collapse of buildings due to ground shaking. Structural engineering could not protect lives of building occupants if the building was buried under tsunami flood; good community planning is essential to mitigate the tsunami disaster in coast areas. Some low-rise reinforced concrete and steel buildings were moved or overturned by tsunami flood. Reinforced concrete structural walls failed by out-of-plane tsunami water pressure; floor slabs were lifted from floor girders by upward water pressure. Peak ground accelerations exceeding 1.0 g (g: acceleration of gravity, 9.81 m/s2 or 386 in./s2) were recorded at more than a dozen strong motion recording stations, but the destructive power of far-field earthquake motions was less for buildings than that of near-field earthquake motions. The seismic vulnerability of existing old buildings should be critically assessed, and vulnerable buildings should be retrofitted.