MICRO-TREMOR OBSERVATION IN YANGON CITY FOCUSING ON THE MICROSEISMS

Abstract

The Republic of the Union of Myanmar and its surrounding area is one of the earthquake-prone areas of the world. The highly active Sagaing Fault runs down the central part of the country over 1,500 km and is 30 km away on the east of Yangon, the former capital city. Meanwhile, there are many old buildings in Yangon which were built up to the mid-twentieth century during British colonial rule. Moreover, there are no seismic standards for office and commercial buildings that are being built in recent years and extensive damage is expected if an earthquake occurs. To evaluate the ground amplification function during earthquake, the authors conducted micro tremor observations at North Dagon in Yangon with consideration of short period (of around 1 s) and long period microseisms. The short and long period seisms involve with ground properties in the top several tens of meters and several hundred meters to several kilometers deep, respectively. A single-point (three components) micro-tremor observation and an array observation were carried out for determining the H/V spectrum and the dispersion curve of the Rayleigh wave, respectively. Then the findings as well as the estimation of the geological structure are discussed based on both results.