5:15 PM - 6:30 PM
[SSS09-P10] Observability of seismic radial anisotropy parameters by the analysis of surface waves and receiver functions based on the MCMC analysis
Keywords:radial anisotropy, surface wave, receiver function , MCMC
Although recent studies have reported the existence of strong radial anisotropy (RA) in the upper mantle/crust beneath the ocean and in the shallow crust directly under volcanos (e.g., Ekstrom & Dziewonski, 1998; Nettles & Dziewonski, 2008; Russell et al., 2019; Jaxybulatov. et al., 2014; Nagaoka, 2020), no constraint for its origin has been obtained from seismic observations. This is partly because the Rayleigh wave sensitivity kernels for vertical S wave velocity β_V and dimentionless parameter η_K, which is recently defined to represent the incident angle dependence of the bodywave phase velocity in RA, are similar, and thus, it is difficult to estimate each independently by surface wave analysis (Kawakatsu 2016). It should be also noted that the inaccuracy of η_K may mean β_V is not determined exactly.
In this study, we try to evaluate the observability of the new parameter η_K using Markov chain Monte Carlo (MCMC) method. In order to confirm the independence of estimations for multiple parameters, the Metropolis-Hastings method analysis is performed using surface wave dispersion data and receiver functions with multiple different incident angles. As a result of preliminary tests on a simple two-layer structure model with radial anisotropy, the trade-off between η_K and β_V can be resolved and both can be estimated accurately in the case that incident angles range between 20-30 [deg] for the S-wave and 20-50 [deg] for the P-wave receiver functions. This result may suggest that the RA parameters can be estimated by combining surface waves and receiver functions even in a more complicated structural model. In the presentation, we plan to clarify how the observability of radial anisotropy changes depending on data corresponding to various observation environments, which may further contribute to future analysis and/or observation.
In this study, we try to evaluate the observability of the new parameter η_K using Markov chain Monte Carlo (MCMC) method. In order to confirm the independence of estimations for multiple parameters, the Metropolis-Hastings method analysis is performed using surface wave dispersion data and receiver functions with multiple different incident angles. As a result of preliminary tests on a simple two-layer structure model with radial anisotropy, the trade-off between η_K and β_V can be resolved and both can be estimated accurately in the case that incident angles range between 20-30 [deg] for the S-wave and 20-50 [deg] for the P-wave receiver functions. This result may suggest that the RA parameters can be estimated by combining surface waves and receiver functions even in a more complicated structural model. In the presentation, we plan to clarify how the observability of radial anisotropy changes depending on data corresponding to various observation environments, which may further contribute to future analysis and/or observation.