Inversion results. (a, b) Hypocentres. Each blue dot shows the median hypocentre of the MCMC samples for each event. The error bars represent the 95 per cent confidence interval derived from MCMC samples. The inverted triangles are seismic stations. The thick grey line in (a) represents the trench. The thick grey line in (b) represents the bathymetry along 136.5° E. (c, d) Median estimates of (c) delay factors and (d) amplification factors of the MCMC samples. (e, f) Probability distributions of the (e) S-wave velocity and (f) quality factor. Red and grey histograms show the posterior and prior distributions, respectively.