Background and Scope - Tohoku, Japan Earthquake and Tsunami of 2011 - page 2

such as these provide important opportunities for coordination and ongoing
collaboration not only on the disaster investigation but also in the development of
improved engineering design and safer, more resilient coastal communities and
ecosystems.
COPRI also supported two Port and Harbor teams that traveled with Japanese
engineers from PARI in May and June 2011 to examine damage to port and harbor
facilities. ASCE will publish their report, “The March 2011 Great Tohoku
Earthquake Investigation of Port and Harbor Structures”, separately.
The radiation leak from the Fukushima Daiichi plant limited the areas available for
field investigation and added an element of concern absent from other COPRI field
investigations. The team avoided the exclusion zone identified by the U.S.
Government, only traveled on the outskirts of the exclusion area when aboard the
Shinkansen train from Sendai to Tokyo. While in the field, all team members carried
radiation dosimeters provided by ThermoFisher Scientific. No team member recorded
any elevated background or abnormal peak readings. Exposure levels compared with
the ambient levels recorded in the U.S. before the field investigation.
1.2 Purpose of the Field Investigation
Members on the ASCE/COPRI reconnaissance team undertook the trip to investigate
the tsunami and earthquake effects specific to coastal engineering structures, coastal
landforms, and coastal processes. Japan has been a world leader in the construction of
tsunami barriers, tsunami walls, protective concrete dikes, seawalls, river walls, and
vertical evacuation buildings for protection from tsunami events. Before the
earthquake, approximately 40% of that nation's 22,000 miles of coastline benefited
from engineered protection. Communities in the U.S. have been interested in some of
these structures, especially the vertical evacuation shelters (see, for example, FEMA
Report 646, Guidelines for the Design of Structures for the Vertical Evacuation from
Tsunamis).
While the devastating earthquake and subsequent tsunami caused extensive damage
to coastal communities, the effects of and on engineered coastal structures and
nearshore features that attenuate wave forces remain unclear . The massive tsunami
waves either overtopped or partially destroyed many of these structures. Loss of life
and destruction of residential and commercial development often followed. Not all
structures failed completely, however. The extent to which the coastal structures
reduced casualties and damages and the performance of the structures themselves
motivated the reconnaissance.
The investigation team focused on the specifics of design and construction of coastal
protection structures, and the siting and design of tsunami protection. Team members
looked for opportunities to learn lessons from failures and successes alike. The
investigation incorporated data from observations on site and interviews with public
works officials as well as with academics and government officials. The performance
of rubble-mound structures and concrete armor units exposed to the tsunami waves