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Japan Earthquake/Tsunami Reconnaissance Team 2 -- April 2011

Resiliency Impresses Geo-Institute Team

A team from the Embankment, Dams and Slopes (EDS) Committee of the Geo-Institute arrived in Japan on April 23 for a one-week engineering reconnaissance of the region affected by the Tohoku Japan earthquake. The three-person team is led by Joseph Wartman, Ph.D., P.E., M.ASCE, of the University of Washington, and includes Binod Tiwari, M.ASCE, of California State University, Fullerton, and Daniel E. Pradel, Ph.D., P.E., D.GE, F.ASCE, of Praad Geotechnical Inc. and the University of California, Los Angeles. The EDS/GI team is being hosted by Professor Keizo Ugai, president of the Japanese Landslide Society and an instructor at Gunma University. The team is also working with the Japanese Geotechnical Society. Team members will be posting updates to the ASCE web site throughout the week. 

Read each day's entries:
Days 1 and 2  |  Days 3 and 4  |  Days 5 and 6 

Days 1 and 2 -- Sunday, April 24 and Monday, April 25

Report by Joseph Wartman 

Our team has spent the last two days visiting the Fukushima region in the company of Profs. Ugai and Wakai of the Japanese Landslide Society and Gunma University. The Fukushima Prefecture is four hours north of Tokyo and about a hundred kilometers from the earthquake epicenter. Despite having suffered high levels of ground shaking (up to 0.7 g), there is surprisingly little damage to buildings and major structures such as bridges; earth structures such as embankments, levees, and retaining walls generally appear to have performed well in the areas we visited. We have been impressed with the resiliency of the transportation networks, which appear to be functioning at nearly full capacity. These observations very like reflect to some degree the stringent building codes used in Japan and the excellent quality of construction works.

We have visited several landslides — some very large — that have affected smaller secondary roads. The photo below is an example of one such landslide of at least several hundred square meters in area.

Landslide into road 
Interestingly, some of the landslides we visited were reportedly triggered not by the main shock on March 11, but several weeks later by a shallow magnitude 7.0 earthquake thought to be related to the larger subduction event. This shallow earthquake resulted in about one meter of mostly vertical surface fault rupture several kilometers in length, as seen below. The fault rupture offset roads, drainage culverts, and at some isolated located, buildings.

Fault in countryside 
We will be continuing north from here to the Sendai region in the coming days.

Days 1 and 2  |  Days 3 and 4  |  Days 5 and 6 

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