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Japan Earthquake/Tsunami Reconnaissance Team 3 -- Day 5

A 'Grim' Level of Destruction Seen

The third of as many as seven ASCE reconnaissance teams is in Japan studying the impact on infrastructure caused by the 9.0 magnitude earthquake and tsunami on March 11. Following teams sponsored by the Structural Engineering Institute and the Geo-Institute, the third team is sponsored by the Coasts, Oceans, Ports, and Rivers Institute, and as such will be focused on damage to port structures. It is being led by Marc Percher, P.E., M.ASCE, a senior engineer with Halcrow Group in Oakland, Calif. He is a structural analyst and designer specializing in marine oil terminals and refinery structures. Percher and/or his teammates will be discussing their findings and experiences in regular posts.   

Read each day's entries:
Introduction  |  Day 1  |  Day 2  |  Day 3  |  Day 4  |  Day 5  |  Day 6

Day 5 -- Sunday, May 15

Flattened marine oil terminal

By Marc Percher
 

We’re starting to get into the SUPER long days of travel, so I’ll caveat the following posting with the fact that I’m somewhere between half asleep and merely two-thirds dead. What’s more fun than touring disaster areas while drunk with sleep deprivation and on overdrive from trying to understand what you see while not falling down a deadly hole? Thankfully our PARI colleagues have been kind enough to do the majority of the driving.

We split the teams again today in order to cover more ground, and oh boy, did we cover ground. Alex, Martin, and I headed off to Kesennuma to see some marine oil terminal damage and capture any other wharf structures we could find. Meanwhile Yoshi and the Bills went off to Ofunato and all points north. Bill will follow up later with information on his group's journeys. In the meantime, let me tell you a bit about what we found in Kesennuma.

The first thing to be said is that we’re now officially in tsunami country. The damage here is really impossible to describe. In every coastal area, once you are below a certain critical elevation, you rapidly switch from normal to total destruction. Imagine a tornado obliterating houses on one side of a street, but not touching the other -- now picture that applied over an entire region. Every step you take and everywhere you look is covered in debris of one sort of another. The damage we saw in Onagawa was very similar, but as Kesennuma is a larger city, the damage is also on a grimly grander scale.

Our first stop was the marine oil terminal at the south side of the city. While the satellite images and early reports prepared us for the worst, the actual site was truly flattened, as seen below. All of the tanks had floated and piping had been thrown around like twigs in a breeze. While the terminal damage was bad, the real problem was that when the tanks failed, they released a large quantity of oil, gas, and diesel that flooded the bay and set fire to many vessels, lighting up the night sky. While walking around the rest of the port, we saw many of these vessels scarred and battered, waiting for a scrapheap.

Intact water tankYet adjacent to the destruction at the terminal was a separate facility that included a large blue water tank in pristine condition, as seen at right. This was an amazing example of density and buoyancy. When I knocked on the tank I received a dull thunking reply, meaning that the tank was likely full at the time of the tsunami. As buoyancy is simply a difference in unit weight between water and a second material, a tank full of water has no buoyant force and therefore won’t float (of course, if it were made of wood, it would float, weigh the same as a duck and therefore be a witch). Of course describing the concept and seeing the reality is not always easily accepted.

Another interesting sight was found further north in the bay at a pile-supported wharf. Typically between the wharf and the adjacent landside, concrete planks are used to span the gap. Often these planks are simple short spans bearing on both sides and without any restraint from vertical movement, because really, what’s going to lift a several-ton piece of concrete?  Well, as it turns out, a tsunami will do so -- see below. The water had rushed in so quickly that it, or the air pressure wave in front of it, was able to pop up these planks and deposit them on the adjacent landside. While it’s easy to think of a car being pushed around by a tsunami (it is buoyant after all, since we can’t fill them with water -- dang!), it’s hard to imagine these heavy solid blocks of concrete being flipped from their positions and slid around, yet that is exactly what happened here.

Concrete slabs shifted around 

The more we travel the country, the more I’m realizing that tsunamis are incredibly powerful to resist and bewildering in their strength. Seeing this damage constantly shocks my sense of normality, and makes me hope that I’ll never have to see a similar event again. Yet, we all know that this is nature at work, and nature rarely cares for the ability of humans to understand what it is capable of and how it acts.


Introduction  |  Day 1  |  Day 2  |  Day 3  |  Day 4  |  Day 5  |  Day 6

 

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