Variation of the levels of the ground microtremors: the effect of the urbanization and the distance from major roads.

Abstract

In order to examine the possible source of microtremors, we investigated the variation of the ground acceleration levels at 47 points in Kanto area. Urbanization rate around the site, site amplification factors, distance from major roads were considered as the possible factor on the level of microtremor. In addition, seasonal change on the level of microtoremors, and the effect of the declaration of emergency states due to COVID-19 on the level of microtoremors, were investigated. However, there are no significant relationship between the level of microtremor and possible factors considered in the study, and there are quite small variations as the seasonal change and the effect of COVID-19 compared to the daily change and site difference.