Japan is a country with a long history of disastrous earthquakes and tsunamis. The name tsunami itself is a Japanese word, meaning harbor wave, so named because the waves rise highest where they are focused into bays or harbors. Tsunami are most commonly generated by earthquakes, but they can also be caused by volcanic eruptions, landslides or rockfalls and asteroid impacts. The Japanese archipelago sits just along the collision zone of four great tectonic plates. The continuous movements and friction of the plates accumulate a lot of energy, released from time to time as earthquakes. Written records of strong earthquakes and their aftermath date back at least 1,600 years. The last great tsunami struck in 2011, when an earthquake of magnitude 9.0 occurred off the Pacific coast of Japan’s Tōhoku region, triggering a catastrophic tsunami killing an estimated 18,000 people.
The coastline of Japan is dotted with stone tablets, bearing warnings like “High dwellings are the peace and harmony of our descendants,” and “Remember the calamity of the great tsunamis. Do not build any homes below this point.” Inscriptions on old stone tablets located near the coastal city of Kesennuma, warn people to “Always be prepared for unexpected tsunamis. Choose life over your possessions and valuables.” The stone tablets referred locally as “tsunami stones” commemorate earthquakes and tsunamis of the past, warning that “If an earthquake comes, beware of tsunamis.”
Most tsunami stones date back to around 1896, when two tsunamis killed about 22,000 people. In Aneyoshi, a small village on Japan’s northeastern coast, the inhabitants fled the tsunami of 2011 by climbing to higher ground, following the warnings of a stone tablet erected there after a tsunami destroyed the village in 1933, leaving only four survivors behind. Some tsunami stones are believed to be 600 years old.
Modern research has shown that it takes just about three generations for people to forget about a disaster. The survivors of a catastrophe pass their stories to their children and their grandchildren, but then the memory quickly fades. Tsunami stones were a way to warn future generations of the potential danger from living near the sea. Today many tsunami stones are slowly decaying, covered by vegetation.
After 1960, when another tsunami struck, large sea-walls were built to protect the coastal towns. However, walls alone can’t protect a community. People need to know of the possible dangers and how to react in case of a disaster.
As a Japanese proverb says,”a natural disaster always strucks when the last one is forgotten.” Inspired by the ancient warning system, modern researchers have proposed to “preserve” buildings destroyed by the 2011 tsunami. The ruins could serve as reminders of the destructive power of tsunami waves. Researchers also collect and publish eyewitness testimonies. Older residents, survivors of the 1960 tsunami, said after the 2011 disaster that they regretted not telling their stories, how they survived the tsunami by climbing on higher ground and staying there, to the younger generations. Many people died in the 2011 tsunami as they returned to their homes immediately after the earthquake, inspecting their damaged homes.