Study On The Correlation Between Ocean Wave Field And Microseisms On Ocean Islands

Compared with the mainland,the island has a relatively unique geographical location,making its background noise with particularity.Microseisms(~ 0.003-1 Hz)is the strongest component of seismic noise.It is generally believed that it is mainly formed by the coupling of ocean waves and submarine ground.Therefore,its excitation and characteristics are considered to be related with the interaction between ocean waves and the solid Earth.Especially,in the typhoon process,strong waves tend to lead to increased microseisms energy.In recent years,some scholars have studied the monitoring and inversion of ocean wave field and typhoon evolution process through microseisms data.However,the relationship between microseisms characteristics and its relationship with ocean wave field has not been fully studied.In this paper,the time-frequency characteristics of the microseisms signals in the island and its correlation with ocean wave field are analyzed by using the continuous recording data of the Western North Pacific island seismic stations,the measured data of the moored ocean wave buoy and the simulation results of the WAVEWATCH-III ocean wave model by combining physical oceanography with seismology.We will explore and explain the characteristics of the microseisms signals and its excitation mechanism from the perspective of oceanography.Research indicates:(1)The intensity of microseisms signals in the island is stronger than in the inland areas;(2)Microseisms especially in the frequency band of 0.12-0.32 Hz become weaker in seasons of summer and autumn(from May to October),while they become stronger in the seasons of winter and spring(from November to next April),and this variation has long existed,which is consistent with the seasonal variation of oceanographic activities in the Northern hemisphere;(3)The microseisms on ocean islands are found to be highly correlated with the ocean wave energy over the adjacent sea and significant ocean wave height from both observation and numerical modeling,which shows that the microseisms are mainly affected by adjacent ocean wave field.This study result also proves the possibility of seismological inversion of ocean wave field using microseismic signals,providing interdisciplinary data support and technical support for ocean surface wave field observation and research in the Marine science research.