The Great Earthquake of a “Small Earthquake” 15:56 on February 25, telling the lessons of 120 years ago

"That's a problem. Is a tsunami coming even with seismic intensity 2 or 3 earthquakes? 』

The teacher asked elementary school students in disaster prevention education in the areas affected by the Great East Japan Earthquake.

The answer is "even if the shaking is small, a tsunami can come."
What does this answer mean? It is nine years since the Great East Japan Earthquake. Now is the story of the tsunami over 120 years ago. (Yuki Uchiyama, Disaster Reporter, Social Affairs Department)

Curator telling the "big earthquake tsunami"

Mr. Kumagai (53) is trying to convey that a tsunami can occur even if the shaking is small.
I am a curator in Rikuzentakata City, Iwate Prefecture, which was devastated by the Great East Japan Earthquake.

Mr. Kumagai has recently been trying to tell about disaster prevention education in the past with a "small earthquake" large tsunami that hit Rikuzentakata in the past. The Meiji Sanriku Tsunami occurred in 1896, 124 years ago.

More than 20,000 dead in "small earthquake" ...

The Meiji Sanriku Tsunami hit the Sanriku region around Iwate Prefecture. Running up to a height of more than 30 meters, about 22,000 people were killed.

What does a "small earthquake" tsunami mean? What Mr. Kumagai showed me is the record of the Meiji Sanriku Tsunami left in the local historical materials.

It described the situation at the time of the earthquake as follows:

"A small quake hit the coast, but people didn't remember it."

In the historical materials, the words "small earthquakes" were written, as well as words that meant that people thought they were normal and didn't mind. And many people who did not evacuate were involved in the tsunami.

Meiji Sanriku Tsunami Seismic intensity is "2 to 3"

Why did a “small earthquake” cause a “big tsunami”? We visited Prof. Fumihiko Imamura of Tohoku University, a leading tsunami researcher. In Prof. Imamura's room, there was a photo that recorded the damage of the Meiji Sanriku Tsunami.

According to Professor Imamura, the seismic intensity at the time of the Meiji Sanriku Tsunami was estimated to be "2 to 3". In the Great East Japan Earthquake, the maximum seismic intensity was “7”. Where does the difference come from?

Why "small tsunami"?

Professor Imamura says that the Meiji Sanriku Tsunami was triggered by a special mechanism called the "tsunami earthquake."

Usually, when a large tsunami occurs, it is accompanied by large shaking. However, in a "tsunami earthquake", the relatively soft part of the plate moves slowly and slowly, generating a large tsunami without large shaking.

The "tsunami earthquake" is a rare phenomenon, but it has also occurred overseas.

Prof. Imamura says that it is difficult to issue a quick tsunami warning even with current observation networks such as the Japan Meteorological Agency due to small shaking.

Prof. Fumihiko Imamura, Tohoku University "It was reported that small tremors lasted a long time in the Meiji era. I knew that a tsunami could occur without a large tremor, and I didn't think that it was okay because the tremor was small. It is important. "

Past lore originated from the Great East Japan Earthquake

The reason why Mr. Kumagai of Rikuzentakata City is particular about passing down the Meiji Sanriku Tsunami. That is the Great East Japan Earthquake.

Kumagai himself lost his close colleague at work, and his home was washed away.

Why did Sanriku, which had been repeatedly hit by the tsunami, suffer such a great deal of damage?

While studying the history of local disasters as a museum curator, I learned more about the Meiji Sanriku Tsunami. Mr. Kumagai felt that he had not been handed down enough in the local area.

"I may remember the Great East Japan Earthquake, but I cannot make use of the lessons of the tsunami before that."

Ken Kumagai: "The tsunami that hit Sanriku is not limited to the Great East Japan Earthquake. We believe it is necessary to pass on the lessons of the past tsunami to the next generation so that we will never repeat our sad thoughts."

"Lessons learned" on a stele

Kumagai is trying to learn the lessons of the past from the many "stone monuments" left in the city.

Rikuzentakata City has registered 19 monuments in the city as cultural assets of the city after the earthquake. We have begun to pass on lessons learned to future generations.

A monument that was built where the tsunami of the Meiji Sanriku Tsunami arrived had four lessons engraved on it.

"If you hear the tsunami, let go and run away"
"Don't build houses in low places"
"It's tsunami agile to high places"
"Beware of tsunami if there is an earthquake"

Every message is an important message, but Mr. Kumagai learned that the lessons of the Meiji Sanriku tsunami include important meaning in the lesson "Beware of the tsunami if there is an earthquake". Was.

Mr. Kumagai "I do not write" big "or" small "here. During the Meiji era, a large tsunami came with a small shaking. Regardless of whether it's big or small, I'm receiving the message of my predecessor to escape if there is an earthquake anyway. ''

For children who do not know the earthquake

A stele with important lessons.

In the meantime, efforts to share past lessons with local elementary school students are about to begin. The number of children who do not know about the earthquake or past tsunami is increasing.

One frame of that approach.

While Mr. Kumagai asked, "What happens before the tsunami?", The children answered, "Great earthquake!" In a normal test, it might be the correct answer.

However, Mr. Kumagai said that he wants to know that a tsunami may come after a "small and long shaking" like the Meiji Sanriku tsunami that hit Rikuzentakata in the past.

Mr. Kumagai "The tsunami may come even if it is not a big shaking. So it is important to escape if there is an earthquake. Please tell your friends tomorrow what is written here."

I want to know the diversity of tsunami

The Sanriku region has been repeatedly hit by the 1960 Chile Earthquake Tsunami, the 1933 Showa Sanriku Tsunami, the 1896 Meiji Sanriku Tsunami, and the great tsunami before the Great East Japan Earthquake.

Furthermore, tsunamis caused by the Nankai Trough Earthquake and other disasters have been reported throughout Japan.

Mr. Kumagai feels the importance of learning the lessons of the past through the survey of the Meiji Sanriku Tsunami. The tsunami is not only the same as the Great East Japan Earthquake.

Mr. Kumagai "I want you to know that the tsunami is diverse. I think that evacuation behavior will change depending on whether or not you have that knowledge. I want to continue to communicate activities so that tragedy does not repeat "

Know the lessons of the past and save lives

I want as many people as possible to know the fact that the belief that a tsunami will not come because it is a small earthquake has killed many people in the Meiji era. The mechanisms of the tsunami are diverse and have various precursors.

"Know the lessons of the past."

I think that is a way to protect many lives alone from the tsunami.

The "Large Tsunami of a Small Earthquake" will be announced in detail on NHK Special on March 7th (Sat) 9:00 pm.

Social Affairs Disaster Reporter Yuki Uchiyama