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Storms, Sea Ice, and Microseismic Noise in Alaska

Description: 

This study investigates how environmental drivers like ocean storms and sea ice affect microseismic noise across Alaska. Ocean storms have long been understood to be the primary driver of microseism noise. At the same time, sea ice suppresses the formation of waves in oceans, dampening microseism production. By examining the long-term correlation of microseismic noise and ocean wave height, we find that the secondary microseismic noise (5-10s) across the whole state is mainly affected by the sea state in the Gulf of Alaska. We also find that the waves in the eastern Gulf produce higher amplitude microseism than the west. Findings from these long-term correlations are substantiated by observed patterns during individual storms. Similar correlation analysis also reveals that the microseismic noise in the 1-2s period band is primarily driven by ocean waves closer to the coast. Seasonally, in the 1-2s period, we observe an abrupt reduction of seismic power due to the onset of sea ice. Because the 1-2s period microseismic noise is driven primarily by waves near the coast, it is coastal ice that is primarily responsible for this dampening effect. These findings are useful in understanding the role of climate in microseismic noise across Alaska. Phenomena with societal significance are visible directly in the microseismic noise, including the onset and progressive break up of sea ice, the movement of storms across the open oceans, and the arrival and end of the annual storm season. In this study, we show how to calculate ocean storm parameters like position, track, and temporal evolution using microseismic noise records. Declining sea ice coupled with increasing extratropical cyclones is also known to accelerate the rate of coastal erosion in Alaska, posing serious threats to the Arctic communities and ecology. We identify the coastal erosion period from the microseismic noise in the 1-2s period band as it is influenced by both sea ice and coastal sea state. We also compare and contrast the yearly variation of the coastal erosion period in northern Alaska on a decadal time scale.

Session: ESC-SSA Joint Session: Climate Change and Environmental Seismology - II

Type: Oral

Date: 5/3/2024

Presentation Time: 04:45 PM (local time)

Presenting Author: Sebin

Student Presenter: Yes

Invited Presentation: 

Authors