March 11, 2021 was the tenth year anniversary of the 2011 Great Tohoku Earthquake and Tsunami. Many lives in Japan were turned upside down from this extraordinary event. I am reminded of the spectacle of a cars on top of buildings every time I hear about a new tsunami, see image below. The loss of life in Japan was near 20,000 and economic losses in the $250 Billion range which is unprecedented for any event like this. For me it was hard to comprehend what it might have been like to live through something like this.
I had an opportunity to visit Japan with the EERI Learning From Earthquakes (LFE) group to review structural damage and performance of protective systems in buildings including buildings with protective systems like supplemental damping and seismic isolation. Once given the OK that the radiation due to the cascading failures at the Fukushima power plant had been contained, we were able to visit the east coast of Japan about three months after the event. Our charge was to visit buildings with protective systems which is much more widespread in Japan compared to the US; for example there are about 2,500 commercial buildings and nearly 4,000 single-family homes with seismic isolation in Japan. Compare that around to around 500 structures in the U.S.
It was exciting and validating to see the improved performance of buildings with protective systems like dampers and isolation, but measuring displacements on the order of centimeters seemed like we were focusing on the wrong thing as hundreds of miles of coastline were destroyed from the tsunami. Many others as part of the LFE team were more adept than I to focus on tsunamis and societal implications. Years after the event, while surfing in San Francisco, there was still debris washing up on our shores that reminded us of the proximity of the disaster. I still think about the communities that lived close to sea and relied upon the ocean for their livelihood only to have been chased from their homes and returned to destruction days later.
How do you explain to a fisherman that a 50 meter high wall makes any sense to mitigate tsunami damage when their lives rely on the connection with the sea? These are questions for us to ponder outside of engineering. It is encouraging to see the resiliency of the communities as they are rebuilt and the “normal” way of life has returned and for many they now live somewhere else. There are lessons for us about the impact of earthquakes and tsunamis from this event, but we can’t forget that sometimes the resiliency we are looking for resides in the community itself.
A note on the photos above:
I took this photo in Onagawa, which is on the coast of Japan in July 2011 after the March 11, 2011 Great Tuhoku Earthquake and Tsunami. Onagawa is an area closest to the heaviest tsunami inundation zone. According to a Japanese Newspaper there was a 45 foot tsunami that destroyed this town. The entire valley was filled with over 70 feet of water, leaving cars on top of buildings that remained standing. We stood at the hospital which was spared by the waves, which is at least 70 above sea level. The hospital first floor was inundated with water. A warning was given to the town but people only had 15 minutes to escape the oncoming wave.
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