[S-CG54] Ten years from the 2011 Tohoku Earthquake: A milestone of Solid Earth Science

[SCG54-05] A Decade of Lessons Learned from the 2011 Tohoku-oki Earthquake

*Naoki Uchida¹, Roland Bürgmann² (1.Research Center for Prediction of Earthquakes and Volcanic Eruptions Graduate School of Science, Tohoku University, 2.Department of Earth and Planetary Science, University of California, Berkeley)

The moment magnitude Mw 9 Tohoku-oki earthquake was one of the most disastrous earthquakes in recent history. The large slip area and slip amount, including in the near-trench area, resulted in strong shaking and a huge tsunami that caused severe damage and casualties in Japan. In this presentation, we review the state of knowledge of the earthquake and tsunami potential of the Japan Trench before the earthquake, and the improved understanding after the earthquake. Pre-Tohoku-oki studies partly recognized the potential of Mw8 or larger earthquakes. However, the knowledge based on different types of observations was incomplete and the occurrence of such a great event was not considered in the governmental estimates of earthquake probabilities. The improved understanding of earthquake-cycle and rupture processes since the Tohoku-oki earthquake advanced the leading edge of efforts to characterize megathrust earthquake hazards. We can summarize the lessons as follows: 1) In addition to individual studies of a particular aspect of earthquakes, interdisciplinary research is essential to advance our understanding of the processes underlying the occurrence of earthquakes. 2) The recognition of earthquake potential informed by geologic evidence extending beyond available instrumental records is essential for assessing the largest possible earthquake in a subduction zone. 3) The development of advanced scientific infrastructure, especially near-source (ocean-bottom) observations is necessary to evaluate the locking state of subduction thrusts and to monitor dynamic megathrust fault-zone processes. 4) Although post-Tohoku-oki studies have better characterized the hazard and a number of possible precursors have been identified, the confident prediction of such events appears impossible in the near future.