Monday, March 28, 2011

Minami-Sanriku before and after

The Sanriku coast I – Minamisanriku before and after

To the right is a Google map image of the towns we visited in April 2010 to learn how they were preparing for tsunamis. This trip was led by Nobuo Shuto and Fumihiko Imamura. We were an international busload. Minami-Sanriku was our second stop, coming up from Sendai.

If you followed the tsunami news at all, you will recognize the name of this town from the references to it as “the town that disappeared.” But many people survived, and many largely due to preparedness. We visited this town in April of 2010 to see how tsunami mitigation had developed. Minami Sanriku is no stranger to tsunamis. Here is a summary of recent historical cases.

1896 Meiji Sanriku and 1933 Showa Sanriku tsunamis. The town experienced two giant local tsunamis in recent 100 years. The Meiji Great Tsunami in 1896 showed the maximum height of about 3.5 m, and the Showa Great Sanriku Tsunami that of about 2.2 m. Information: Nobuo Shuto

Chile 1960 tsunami. The tsunami from Chile in 1960, reaching heights up to 5 m, destroyed the town and killed 41 residents. Thus in the public square near the shore there is a gift monument from Chile (a replica of an Easter Island monument) in memory of those victims. It was snowing when we were there in mid-April 2010.
"One of my neighbours who ran with her three-year-old baby strapped to her back later realised that the child had fallen off and been swept away as they struggled in the water," Shiba said. "It was terrible." "I was pregnant at the time and had to hang from the edge of a wooden roof when the water and debris gushed into my house," said Shiba, adding: "The baby died just one day after she was
born." Across Japan's Pacific coast the death toll from the 1960 quake -- the strongest on record with a magnitude of 9.5 -- reached 142. -- from 1 March 2010

Chile 2010 tsunami. When in 2010 (the 50th anniversary year of Chile 1960) Chile had another great subduction-zone earthquake and tsunami, Minamisanriku residents were ready for its arrival. The river gate (see photo) came down to keep the tsunami at bay, people evacuated to higher ground, and no one died, though there was damage to aquaculture and harbor structures.

(news article of 1 March 2010) --"Japanese grandmother Matsuko Shiba rests at an evacuation shelter in Minami Sanriku Town on February 28 2010. When Chile's massive earthquake sent a tsunami racing towards Japan at the weekend, Shiba knew to head for high ground, and for good reason. Half a century ago a killer wave from the South American country destroyed the picturesque fishing town of Minami Sanriku. Another refugee in 2010, Yoshida, watching her carefree grandson, said that her town 50 years ago received a lot of help from people across Japan. Today, she said, 'we also need to help people suffering from disasters overseas. And, we, the elderly, need to talk more about what we experienced to the younger people.' " -- from 1 March 2010

Our visit in April 2010

It was a cold, wet day when we visited Minami-Sanriku on 12 April 2010. Our leaders took us to the waterfront, where a river gate was the main point of our stop, and we also walked in the park and saw the many tsunami monuments. The rain turned to wet snow. I look around at how flat is was and how close to sea level, taking pictures of an apartment building that was clearly labeled as a vertical evacuation structure for those near the waterfront. This particular piece of land was intentionally left just as a park because at high tsunami risk, and people could evacuate to the nearby tall, reinforced concrete building if there was a tsunami warning.

These gates are meant to keep tsunamis out. I suppose they may also be used for storm surges. They take time to activate and lower the gates, and on the day we visited, they could not get the gate down. In the 2010 Chile tsunami, they had plenty of advance warning, and the gate worked. They gave us a handout describing how they were trying to decrease the time to gate lowering with the possibility of using it for locally generated tsunamis.

Below is a "before" map showing the location the three features we saw on the waterfront of Minami-Sanriku in April 2010.

11 March 2011 Tohoku earthquake and tsunami hit Minami-Sanriku

You can see below in this post-tsunami image that the 4-story building stood, and what I read makes me think that people on the top of this building, which is now half-surrounded by water, survived. It also looks like the river gate is still there, but with severe erosion around the left bank. The tsunami would have significantly overtopped the gate, and in any case, I don't think there was time to bring it down. The park's trees have been washed away, from this view it's hard to see much else, but it's likely all the monuments were toppled and transported some distance, but they may be salvaged.

NHK World, 28 March: A 4-story public apartment building in the coastal area was almost completely inundated, suggesting that tsunami up to 16 meters reached the building.

The town hall was a three story building in the center of town. The mayor, Jim Sato, was one of about 8 or 10 that survived on the top of it, by clinging to things like steel railings, while about 20 others were washed off the top of the building, about 13 meters high. After the tsunami the building is a skeletal wreck--I saw images on an NHK documentary last weekend. The nearby hospital (the largest building complex in this oblique view) withstood the tsunami, with staff moving patients higher and higher, to the fifth floor; the tsunami reached the fourth floor (from NHK documentary).

16 March – town 10,000 missing:

19 March – situation terrible, some reason for hope:

Although the numbers of dead and missing are increasing, there are now about 10,000 survivors accounted for; the mayor holds out hope that many still not documented left town for other places, but the fatalities are sure to rise:

When the Observer asked mayor Sato to account for the discrepancy, he said the problem lay in the manner of counting. "At first we assumed only the 7,000 at the public shelters had survived, but we realise now that many others sought refuge with friends or left the town. That was our mistake. I still can't tell you how many are dead. We still don't know how to make an accurate estimate."

From IOC/UNESCO report of 28 March 2011

Minami-Sanriku T







7 km2 flooded of 164 total

  • Many areas are inundated
  • Tsunami ht by Waseda U. Evacuation building: 15.4 m

There are many terrible images of this fishing village post-tsunami, but I am choosing to focus on the survivors such as these children in an evacuation center at a secondary school in Minami-Sanriku.

Photograph: Stephen Morrison/EPA

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