Summary of geotechnical activities in response to the 2011 Tohoku earthquake; follow-up of my TC203 Ishihara Lecture in 2019

Abstract

The devastating earthquake in Tohoku Region of Japan in 2011 caused many geotechnical problems and the recovery from them was an unforgettable experience. This paper describes first the seismological background of that extreme event whose return period was longer than 1000 years, producing unprepared situation among people. The geotechnical effect of this earthquake consists mainly of collapse of sea walls due to overtopping of tsunami water and liquefaction-induced damage of levees and residential lands, while landslide was fortunately of minor scale. Much efforts were made after the earthquake on establishing hazard assessment methodology for residential land and ground improvement under existing houses. The recovery from the nuclear incident is still going on. These issues were presented during the 2019 Ishihara Lecture during the seventh International Conference on Geotechnical Earthquake Engineering in Rome organized by the Technical Committee 203 of the International Society for Soil Mechanics and Geotechnical Engineering and were published in the conference proceedings. However, there is a tradition that every Ishihara Lecture has been published in this International Journal of Soil Dynamics and Earthquake Engineering. In view of this, the original publication was totally rewritten and new information was added so that a second publication might be possible as a follow-up.