Ambient seismic noise difference between Chukchi Sea and Interior Alaska

Based on the background of receding Arctic sea ice and increasing exploration activities offshore Alaska, we explored the sea-land differences in seismic noise characteristics between the Chukchi Sea and the inland of Alaska, for which the Chukchi Sea OBS data obtained from the Ninth Arctic Scientific Expedition and the continuous waveform data from Alaska seismic stations were used, the temporal and frequency distribution characteristics of the noise were analyzed using the power spectral density and probability density function methods, and the sources of the noise were identified and described from the information on sea-ice density, ocean waves, river flow, and human activities. Result shows that in the microseismic zone, the ambient seismic noise intensity in the Chukchi Sea varies significantly between ice and ice-free periods: sea ice cover suppressed the dual-frequency microseismic energy, whereas the enhanced wave activity in the ice-free period significantly increased the microseismic noise. Seasonal variations in double-frequency microseismic peaks were revealed in the inland Alaskan stations and correlated with distant-source Arctic Ocean storms, showing a slight shortening of the peak period in summer and autumn. On the short-period scale, the Chukchi Sea OBS (Ocean Bottom Seismometer) records intermittent high-energy noise from wave–ice-floe collisions, while the inland stations are susceptible to a combination of river turbulence and human activities, and show clear seasonal and diurnal variation patterns. The higher ambient seismic noise intensity in the Chukchi Sea over a long period is related to submarine currents, whereas that in the inland stations is generally low and stable.