Applications to World Heritage Sites

Abstract

It is important for the countermeasure against earthquake damage not only to learn the earthquake damage history, but also to grasp exactly the vulnerability of ground and structures. Especially, the historical structures as the world heritages are usually exposed under the dangerousness of the damages caused by the earthquake motion because of the hidden weak points with long history. In general, it is difficult to inspect or understand the behavior of such kind of structure because of the complex structure, no design plan and so on. And also, it is impossible to get test pieces or oscillate the structure. So it is useful to use microtremor as a tool to inspect the structures and understand the dynamic characteristics. The microtremor, ambient noise, exists anywhere and the microtremor measurement requires no long time and any vibrators so there is no possibility to injure the measuring objects. So it is useful and applicable for the inestimable facilities like the world heritages. Recently, the H/V spectral ratio is popular for the vulnerability investigation of both ground and structures because the H/V spectral ratio can show the predominant frequency and the amplification characteristics. And some indices as the K values are introduced for the vulnerability index. Here shows some result of the vulnerability assessment of mainly the world heritages and the surrounding area using the microtremor. And some of them show the changes before and after the damaging earthquake and the stability of long time span.