Japan, tsunamis, Katrina, and other natural hazards

I haven't blogged in a long time, and yes, although we were probably 300 km away from the earthquake, tsunami, and nuclear triple disaster this past March, that event was one reason.  But the truth is I mostly got really busy with my work.  Now I just wanted to share second-hand information from a Japanese, about Japan and its battle against earthquakes and tsunamis, and to talk about the similarities with New Orleans and Hurricane Katrina.

A friend said that Japan might now increase its efforts even more in seismic and tsunami engineering research. I replied that it feels like there's not much more that can be done at least in tsunami research.

Before this year's tsunami, they already experienced not more than 10-meter high tsunami waves years ago.  The devastation was massive.  And so they built this likewise huge 10-meter high seawall/dike that is said to be longer than The Great Wall of China along the country's northeast/Pacific coast.

And suddenly comes this Magnitude 9 earthquake and 20-meter+ tsunami waves.

I guess they'll build taller walls, or totally vacate those tsunami-prone areas. But I think the latter is not an option.

There is one place affected by the tsunami where fishing is their main livelihood, and they opted not to have that 10-meter high seawall built for their village or otherwise it would be difficult for them on a day-to-day basis to fish. Instead, they had a yearly tsunami evacuation drill. Out of about 110 residents, only one person died and probably because he/she was in another village. At the more affected locations, something that I hesitate to call The Katrina Phenomenon happened.

Like Japan's Tohoku (Northeast) region, they built these huge dikes in New Orleans and people thought it was now safe to live there. We all know what happened after Katrina.

I guess more than anything, the focus now is re-evaluating what level of hazards should structures and communities be designed for, and that applies to typhoons/hurricanes, tsunami and earthquakes, tornadoes, and so on.

Perhaps a classic example is in the design of "temporary" structures, such as scaffoldings and staff housing used during construction.  In practice these are designed for, say, 1-year return period events, whereas typical buildings, including the buildings being constructed where such scaffoldings and staff homes are used might be designed for, say, 50-year return period events.  But what if a 50-year return period event occurs while these temporary structures are in use?  Catastrophe is certainly expected.  The question is, are we all willing to accept the consequences?  Better yet, let us ask that question this way.  If we have a loved one working in the construction field, and for most of his whole adult life he will use these scaffolds and temporary housing and so on, are we willing to accept the loss of that loved one when, say, a very strong earthquake or other event occurs that far exceeds the design strengths of these temporary structures?

Conversely, are we willing to spend or sacrifice enough so that we can all be safe no matter what mother nature might throw at us?

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