Takumi MATSUMOTO

Estimation of site amplification factor in Yangon City

Takaaki IKEDA

Our research focuses on seismic risk assessment in Yangon City, Myanmar. There is plate boundary around Myanmar, and the active fault runs in the central part, so the earthquake risk is very high. The ground motion due to an earthquake may cause greatly damage. In this study, for the purpose of seismic disaster mitigation, we estimated the site amplification factor of surface ground.
The target area was 568 wards of Yangon City, and the difference in vulnerability was expressed by creating the hazard map color-coded by site amplification factor. In this study, we estimated the site amplification factor from three methods. (1. Estimation using soil classification defined by the earthquake assessment study in Tokyo 2. Estimation using microtremor measurement 3. Estimation using boring data) The estimation of method 1 to method 3 was advanced in order, and high-accuracy hazard map was finally created. In addition, we confirmed the estimation accuracy using topography and grasped the features of the area with large site amplification factor.
Finally, the hazard map was created by using the results of method 2 and method 3. The site amplification factor reflecting the ground characteristics in Yangon City was estimated from the result of microtremor measurement and boring data. The results indicated that the site amplification factor of Yangon City was relatively large. In addition, it was assumed that the site amplification factor was correlated with conditions such as geochronologic classification and elevation. As a method of estimating the site amplification factor, the effectiveness of microtremor measurement, boring survey and topography was confirmed. The hazard map created in this study clearly showed the vulnerability in Yangon City, which will be used for seismic evaluation of structure and urban development in the future.