Determining Shear Wave Velocities at a Deep Sediment Site in the Mississippi Embayment Using Rayleigh Wave Dispersion From Active and Passive Sources
Description:
Rayleigh wave dispersion curves for a deep sediment site near Memphis, TN, are determined from small-scale refraction data, ambient noise interferometry from a dense 3km long profile of 60 nodal seismometers, and direct observation of explosion surface waves from two 91 kg explosions at the ends of the same profile as part of the Embayment Seismic Excitation Experiment (ESEE2022) that occurred in late July/early August 2022. The data span two orders of magnitude in frequency from 0.5 to 50 Hz and offer an opportunity to evaluate the consistency between dispersion measurements taken from passive and active seismic sources and resulting differences in derived shear wave velocity models. We have initiated this comparison using the two active-source, 48-sensor linear arrays for near-surface soil characterization. Multi-channel Analysis of Surface Waves (MASW) and refraction microtremor (ReMi) were used to provide model estimates to depths of approximately 30m. Because hammer blow sources excite higher frequency Rayleigh waves than occur in ambient noise, MASW has less resolution for deep layers than REMi. Constrained inversion of dispersion gives near-surface shear wave velocities of 175-225 m/s increasing to 600-800 m/s at 30m depth. The shear wave velocity structure of the entire 900m thick unconsolidated sediment section is the target of using dispersion from ambient noise interferometry and explosion Rayleigh waves recorded by the 3km nodal array. A comparison of Rayleigh dispersion and models from these two datasets is in its initial phase and will be presented.
Session: Site-specific Modeling of Seismic Ground Response: Are We Quantitative Enough to Predict? [Poster]
Type: Poster
Date: 4/19/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Charles A. Langston
Student Presenter: No
Invited Presentation:
Authors
Zoya Farajpour Corresponding Author zfrjpour@memphis.edu University of Memphis |
Charles Langston Presenting Author clangstn@memphis.edu University of Memphis |
SM. Ariful Islam s.m.ariful.islam@memphis.edu University of Memphis |
Chidozie Opara copara@memphis.edu University of Memphis |
Galen Kaip gkaip@utep.edu IRIS Source Facility, University of Texas at El Paso |
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Determining Shear Wave Velocities at a Deep Sediment Site in the Mississippi Embayment Using Rayleigh Wave Dispersion From Active and Passive Sources
Category
Site-specific Modeling of Seismic Ground Response: Are We Quantitative Enough to Predict?