Generally,most hard engineering countermeasures were not designed to face tsunami createdby high magnitude earthquake. As a result, many of them would be destroyed, andthe tsunami would not be stopped. In 2011 Japan was hit by a tsunami caused bythe biggest earthquake in its history. Even the most tsunami-protected areas inthe country with highest tsunami-awareness were not prepared to face suchdisaster. So most of hard-engineering structures included breakwaters,embankment walls, water gates and control forests failed to protect.
Thefailure of hard engineering methods reminds us that structural measures aloneare not enough to protect community and properties from a such disaster. Whilethese construction techniques could reduce the impact, they should be designedto survive even when the tsunami overflows. Coastal residents should alsounderstand the function and limits of hard structures.
On thisbasis, non-structural measures, such as monitoring, are very important topromote rapid evacuation in the event of a tsunami. An adequate communicationsystem for tsunami warnings and more evacuation accommodation with evacuationroutes in good condition could support a safe evacuation process. Thecombination of hard-engineering and non-structural measures is very importantto reduce the loss during big tsunami. Nonetheless,in 2011 the first tsunami warning was announced 3 minutes after the earthquake asis normal. But underestimation of earthquake`s magnitude caused the underestimationof the projected tsunami height. Another problem was the inappropriateannouncement of tsunami observations. All observed tsunami heights wereannounced based on time, when waves were still small, which led some people tobelieve that evacuation was unnecessary. So, it is also important to work with localcommunities to increase their awareness and give some experience andinformation about tsunami.