The 11 March 2011 magnitude 9.0 earthquake off the northeast coast of Honshu was the fourth largest earthquake in the world and the largest in Japan since instrumental records began more than 100 years ago. The unanticipated earthquake sequence produced severe strong ground motions onshore, a tsunami wave train that wreaked death and destruction in nearby onshore areas, and damaging tsunami waves across the northern Pacific basin. These events in a country with strict seismic standards for building construction and years of earthquake preparation provide lessons about current seismic design practices relevant for other regions susceptible to great subduction zone earthquakes, including Cascadia. This symposium will summarize the tectonic origin of the earthquake, quantify the ground-shaking characteristics extensively recorded by the advanced monitoring networks in Japan, and explain the local and remote propagation of tsunami waves. The panel will review the initial effects and emergency responses regarding local communities, industrial facilities including the Fukushima Diachi nuclear power facilities, and distant ports and harbors. Longer-lasting consequences will be reviewed, including national and international economic impacts and repercussions for nuclear power systems in Japan and around the world. The session will conclude with an exploration of the impacts of beyond-design-basis seismic events on current hazard assessments and engineering design approaches.