2019/10/23 by Kenneth Muhumuza, Muhumuza, Kenneth
Earth and Planetary Sciences · Engineering · #Applied Physics (physics.app-ph) #FOS: Physical sciences #Geophysics (physics.geo-ph) #Geophysics and Sensor Technology #Seismic Imaging and Inversion Techniques #Seismic Waves and Analysis
paper · pdf · doi:10.48550/arxiv.1910.10767
openalex publication_date 2019/10/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
This work assesses the feasibility of the direct use of surface-wave\ndispersion curves from seismic ambient noise to gain insight into the crustal\nstructure of Bransfield Strait and detect seasonal seismic velocity changes. We\ncross-correlated four years of vertical component ambient noise data recorded\nby a seismic array in West Antarctica. To estimate fundamental mode Rayleigh\nwave Green's functions, the correlations are computed in 4-hr segments, stacked\nover 1-year time windows and moving windows of 3 months. Rayleigh wave group\ndispersion curves are then measured on two spectral bands; primary (10-30 s)\nand secondary (5-10 s) microseisms, using frequency-time analysis. We analyze\nthe temporal evolution of seismic velocity by comparing dispersion curves for\nthe successive annual and 3-month correlation stacks. Our main assumption was\nthat the Green's functions from the cross-correlations, and thus the dispersion\ncurves, remain invariant if the crustal structure remains unchanged. Maximum\namplitudes of secondary microseisms were observed during local winter when the\nSouthern Ocean experiences winter storms. The Rayleigh wave group velocity\nranges between 2.1 and 3.7 km/s, considering our period range studied.\nInter-annual velocity variations are not much evident. We observe a slight\nvelocity decrease in summer and increase in winter, which could be attributed\nto the pressure melting of ice and an increase in ice mass, respectively. The\nvelocity anomalies observed within the crust and upper mantle structure\ncorrelate with the major crustal and upper mantle features known from previous\nstudies in the area. Our results demonstrate that the direct comparison of\nsurface wave dispersion curves extracted from ambient noise might be a useful\ntool in monitoring crustal structure variations.\n