Abstract: We carried a research on main frequency characteristics of gravity disturbance signals before Yutian M_S7.3, Ludian M_S6.5, Jinggu M_S6.6 and Pishan M_S6.5 earthquakes, as well as gravity disturbance signals induced by typhoon ‘Huangfeng’, ‘Weimaxun’, and ‘Maidemu’, based on continuous gravity observations from Crustal Movement Observation Network of China (CMONOC). The results show that the gravity disturbance signals before earthquake and induced by typhoon cannot be distinguished with its main frequency which is similar and all correspond to 4~7 s. The range and standard deviation of gravity disturbance signals before earthquake are both lower than 0.02 Hz without any influence of typhoon, in contrast, they are both higer than 0.02 Hz when it is induced by typhoon. The range and standard deviation of main frequency can be used to separate the gravity disturbance signals before earthquake from typhoon effect. This work will greatly improve the applications of the continuous gravity observations in earthquake short-term monitoring.

Key words: Gravity Disturbance, Gravity observation, Typhoon, Main frequency