Abstract Database


Ngun Za Iang
Supervisor: Saeko KITA
Country: Myanmar
In order to estimate completeness magnitude of earthquakes and b-values, the NEDC local dataset was used during 2014-2018. This study aims to estimate the completeness magnitude of earthquakes in Myanmar and to examine the b-value with its relations: depth, faulting style, and stress accumulating in a sophisticated tectonic setting of Myanmar. The completeness magnitude Mc was estimated as ML 2.8 with a b-value 0.68±0.02 in the whole study region. Regionally, the b-values vary from 0.52 to 1.0. The tendency relation between b-value and faulting styles was found along the Sagaing Fault. The southern part with a smaller b-value indicates a thrust mechanism, whereas the northern part with a larger b-value shows a strike-slip mechanism. The b-value generally increases with the increase of depth in the whole study region. In the active fault region, the b-value decreases with depth within the upper crust at depths of ~15 km, which might be related to high-stress accumulation. Below at a depth of 15 km, the b-value then increases with a function of depth. In contrast, a significant decrease of b-value with depth was observed at depths of 75-85 km in the subduction zone of the study region, which might be discussed with the process of dehydration in the ocean crust. The methodology of this study might be fruitful to understand the seismically complex tectonic system beneath Myanmar.
Keywords: b-value, completeness magnitude, maximum likelihood method, stress, Myanmar.