Monday, May 2, 2011

Soil collapse after Japan earthquake

Severe liquefaction and shift in soil occurred as a result of the 9.0 earthquake in Japan this year.   As a reminder from one of my previous posts, the processes of liquefaction temporarily changes sand from a solid to a liquid state causing piles of sand to erupt on the surface.  Japan's liquefaction occurred over hundreds of miles.  This surprised experienced engineers.

Questions about whether existing building codes in other vulnerable locations here in the United States are adequate since the levels of liquefaction were higher than expected in Japan.  Hopefully we will learn something from Japan and be able to mitigate risks in other similar events.  

"We've seen localized examples of soil liquefaction as extreme as this before, but the distance and extent of damage in Japan were unusually severe," said Scott Ashford, a study team member from Oregon State University.

It is speculated that the long duration of five minutes of the Japan earthquake, is the key to severe liquefaction.  This may force researchers to reconsider the extent to which liquefaction is possible.  The age of the sediments is another factor the extent of liquefaction.  Younger, clean sediments cause higher liquefaction.  Shallow groundwater contributes to a higher level of liquefaction.  

Engineers can apparently still be surprised....
Soil sank nearly 3 feet.  Source:

Click here for the article.

1 comment:

  1. This makes me wonder if we are in for more and more surprises as the climate continues to change, development and population increases, etc. Could make engineering more and more challenging.