The earthquake precursor information of gravity tide in Yunnan based on improved ICA
ZHANG Aiyi1， QUAN Haiyan1， YI Xinbao2
1.Faculty of Information Engineering and Automation， Kunming University of Science and Technology， Kunming 650500；2.Xishuangbanna Vacational and Technical College， Xishuangbanna， Yunnan 666100
Abstract：Gravity earth tide signal is a kind of complex mixed signal which is caused by effect of the Moon and the Sun on the Earth rotation. The observed gravity tide includes much earthquake precursor information. An orthogonal decomposition model of gravity earth tide is proposed to decompose the gravity earth tide into two orthogonal direction， in order to extract the independent harmonic components from the gravity earth tide. The independent harmonic component are longperiod waves， diurnal wave， and semi diurnal wave. Independent Component Analysis (ICA) is introduced in analysis of earthquake precursor information in gravity tide， which is used to analysis the three kinds of harmonic component. According to analysis on the longperiod wave， the instantaneous sequence variation characteristics is studied. The Yunnan earthquakes cases show that longperiod wave exists abnormal variation， and the changes emerge 30 days before and after the earthquake. The change of the abnormal variation is easy to observe and analysis， which has clear physical meaning to the analysis of the earthquake.
