Links between microseisms and extreme waves during typhoons

Ocean-Solid Earth coupling is the main forcing of generating seismic noise. It has been well known that seismic noise in the frequency band from 0.05 to about 1 Hz results from ocean waves. Components of noise spectrum, also called microseisms, are used to study extreme waves during typhoons. During the KUN-SHEN project (2011-2014), wave measurements have collected at the Cigu coast of Taiwan and compared with microseisms observations at inland seismometers from Broadband Array in Taiwan for Seismology (BATS) network. By comparing between background and storm induced microseisms, peaks in the noise spectrum can be divided in to two frequency bands. Comparison of microseism band between 0.1 and 0.2 Hz with buoys in the deep sea shows a strong correlation of seismic amplitude with storm generating waves, implying mat this energy portion could originates at the remote regions. Microseism amplitudes above 0.2 Hz show a good correlation with wind-generating waves near coasts. Findings also show mat maximum amplitudes of two different portions have the significant time lag, implying that source locations of generating microseisms can be identified. Results indicate that secondary microseisms observed at inland sites can be a potential tool of tracking typhoon motions and monitoring extreme waves near coasts in real time. Seismic noise in the l-10Hz band has rough correlation with wave activities in swash zone. Further examination is required to investigate those differences.