Syafriani, Yulkifli, A.Z. Sabarani, F.D. Raharjo
West Sumatra is a tectonically active area where there have been several major earthquakes happened. Earthquakes can happen anytime and anyplace, so that need to know some precursor of earthquake before the earthquake occurred, such as local stress condition of region. Interrelationships between of the local stress condition a-value, b-value and z-value for the time period extending from 1981 to 2015 are examined in the West Sumatera region. For this purpose, a distribution relationship with the frequency-magnitude earthquake and temporal changes of this parameters were analyzed in order to reveal the potential of future earthquake in the study region. Beside that, standard deviation value of Z-value was estimated in the beginning of 2015 to identify of current seismicity rate changes. The result showed that the area had low spatial variation of b-value around 0.8. Low b-value indicated that the area had high stress condition and a-value had low spatial variation between 5.5 to 7 with low seismic activity. In contrast, several region had positif z-value that indicated that there were significant decreased in seismic activity. Based on this analysis it appears that these three parameters (a,b,z value) were related to each other. In some part of West Sumatra there were region that decreased earthquake activity and indicated that there was a large accumulation of energy which high local rock stress condition with significant decreased in seismic activity or seismic quiescence. This mean that the potentially devasting earthquake can be happened in West Sumatera. © Published under licence by IOP Publishing Ltd.
Departement of Physics, Faculty of Mathematics and Science, Universitas Negeri Padang, Indonesia; Indonesian Meteorology, Climatology and Geophysics Agency, Indonesia
