Analysis of microseisms caused by storm and typhoon

We investigate the phenomenon of microseisms caused by storm and typhoon based on the data collected from gravimeter and broadband seismograph of Tai’an station in Shandong Province since 2016 by using the method of time-frequency analysis. The results show that the frequency of microseism signals produced by these two weather processes almost distribute in the range of 2−20 s, and their energy mainly concentrate on 5−7 s, and there is an energy steadily enhanced frequency band near 15 s. Microseism signals generated during storm have a dynamic characteristic of a decreasing frequency.In fact, the microseism signals generated under both weather conditions show a continuous, high frequency and long duration nature, which reflects the moving characteristic of the excitation source of microseisms signals. Considering the correspondence between the microseisms of Tai’an station and the storm and typhoon, it reveals that the microseism is a kind of micro vibration process, which is related to the offshore storm or typhoon in open sea, rather than a precursory anomaly associated with earthquakes.