Tsunami Mitigation Systems During Tohoku Earthquake
Peer response 1
Response to Question #1
The Tohoku earthquake struck Japan in 2011, going down as one of the greatest earthquakes in history. The earthquake had a magnitude of nine and was known as the Great East Japan Earthquake. The epicenter was located 48 miles off the Tohoku region on the Sanriku Coast, sending a large tsunami towards this region. The earthquake was so massive that it moved the Han Shu Island 14 feet and shifted the earth’s axis more than six inches.
The Tohoku earthquake killed 16,000 people and injured 6,000. The Japanese government had invested in physical mitigation systems for this very scenario. Tsunami break waters were built in the Sanriku coast to break the incoming waves that would be generated from deep sea earthquakes. They were designed based off two of the largest earthquakes in history at the time, the 1896 Meiji Sanriku and the 1960 Chilean.
The Tohoku earthquake sent waves higher than anyone could have imagined or designed for. The break waters did help with preventing a larger tragedy but were not high enough to combat the massive waves (Cuadra, 2022). A second mitigation system built that failed during the 2011 Tohoku earthquake were sea walls. Over 190 kilometers of the 300-kilometer sea wall was either damaged or broken when the tsunami was over.
The tsunami waves generated had reached three to four meters over the sea walls, destroying any in its path. The sea walls were designed to protect people from high tides and typhoons except. There was a section 2.4 kilometers long that was specifically made for tsunami’s because that town was prone to getting them in the past. The They were 10 meters tall, and yet the tsunami waves from the earthquake still managed to demolish the eastern portion of this sea wall and even raise above the sea wall at some sections (Suppasri et al., 2012).
Cuadra, J. (2022). Week 10 Video Lecture: Tohoku Kanto Earthquake Japan. [Weekly Lecture Video]. Retrieved from Tohoku Kanto Earthquake Japan Video Lecture: (PAD4380.sp22) Disasters: From Shock to Recovery (fsu.edu)
Suppasri, A., Shuto, N., Imamura, F., Koshmura, S., Mas, E., Yalciner, A. (2012). Lessons Learned from the 2011 Great East Japan Tsunami: Performance of Tsunami Countermeasures, Coastal Buildings, and Tsunami Evacuation in Japan. Pure and Applied Geophysics. 170, 993-1018, DOI 10.1007/s00024-012-0511-7.
Peer response 2
Describe two tsunami mitigation systems that failed during the 2011 Tohoku earthquake.
In March of 2011 Japan suffered one of the greatest earthquakes in history (Cuadra, 2022). However, Japan is an industrialized country and was well aware of its vulnerability and susceptibility to earthquake and tsunami type disasters. As compared to other cases we’ve studied this semester in which tsunamis or cyclone’s threatened coastal communities, Japan was much more well prepared for and equipped to respond than they were.
Japan had several mitigation systems in place to help thwart threats to life and property. Tsunami breakwaters, sea walls, and tsunami gates were in place and their construction was engineered based off great tsunami disasters Japan faced in years gone by (Cuadra, 2022). However, in this case, the tsunami that impacted Japan’s eastern coast as a result of the massive earthquake overpowered many of these mitigation systems. Although Japan made a valiant effort to mitigate their risk, the scale and magnitude of this disaster was not able to be harnessed and corralled by Japan’s systems. As a result, much of Japan’s infrastructure was destroyed and thousands of lives were lost.
Included in this destruction was Japan’s power grid as several nuclear power plants were damaged or destroyed (Okada Noria et al, 2011). Japan attempted to respond to failing power plants by introducing water as coolant to overheating systems which in turn created and steam. The pressure from the steam contributed to the failing systems ultimately resulting in catastrophic loss (Okada Noria et al, 2011).
Japan created marvelous manmade mitigation systems to help relieve the impact of such a disaster but ultimately mother nature overpowered and washed away wooden homes. Japan did well in enforcing building codes and using concreate construction material which helped with the initial earthquake. This seemed to be a very unfortunate case illustrating that sometimes even though people have really tried to mitigate and prevent disaster, it is out of human control.
Cuadra, J. (2022). Tohoku Kanto Earthquake Japan Video Lecture. Tallahassee: https://canvas.fsu.edu/courses/188584/pages/tohoku-kanto-earthquake-japan-video-lecture?module_item_id=3572380.
Okada Norio1, T. Y. (2011). The 2011 Eastern Japan Great Earthquake Disaster: . Int. J. Disaster Risk Sci., pp. 34-42.