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Seafloor Topography Controls Primary Microseism Generation: New Insights From Cyclone-forced Seismic Observations in Northeastern Australia

Description: 

Primary microseisms are long-period seismic waves generated by the interaction of ocean surface gravity waves with the seafloor, yet the spatial distribution and excitation mechanisms of their sources remain poorly resolved. Here, we investigate the heterogeneous generation of primary microseisms associated with seasonal tropical cyclone activity and Cyclone Ita in North-east Australia (2014). Combining continuous seismic data from a regional network with high-resolution (30 m) bathymetric maps, we show that primary microseism excitation is highly localized in both time and space, and critically dependent on fine-scale seafloor roughness. Our analysis reveals that the most energetic Rayleigh wave bursts originate from regions with pronounced bathymetric variability, where coupling between ocean waves and the solid Earth is most efficient. The finding provides observational evidence supporting the theoretical conjecture that topographic undulations at scales comparable to ocean-wave wavelengths govern the strength of microseismic sources in the 10–20 s period band. Our findings highlight the critical role of nearshore bathymetric roughness in shaping the spatial coherence of primary microseism excitation. These understandings are essential for guiding the future applications of persistent seismic sources in seismic imaging of Earth’s near-surface structures and for monitoring the evolution of the seismic wavefield.

Session: New Frontiers in Seismic Observations and Modeling with Innovative Methods and Emerging Data on Earth and Other Planets - I

Type: Oral

Date: 4/17/2026

Presentation Time: 10:45 AM (local time)

Presenting Author: Thanh Son Pham

Student Presenter: No

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