Beyond Receiver Functions: Green's Function Estimation by Transdimensional Inversion and Its Application to OBS Data

Abstract

Receiver functions, calculated by deconvolving P (or vertical) component records of teleseismic waveforms from the corresponding SV (or radial) components, have been widely used to obtain receiver‐side Green's functions in an approximate form. Conventional receiver function methods, however, often fail due to numerical instability of the deconvolution and strong multiples on the P components. These problems become severe when analyzing in high frequency and using data from ocean bottom seismometers (OBSs). We present a novel technique to estimate Green's functions of receiver‐side structure from teleseismic P waveforms. In this method, two components of Green's functions, which are assumed to form a series of pulses, are directly related in a single equation without explicit deconvolution. Based on the equation, we construct posterior probability distributions regarding the number of pulses, their timing, and amplitudes within a transdimensional Bayesian framework. A reversible‐jump Markov chain Monte Carlo method is used for this purpose, and we further utilize a parallel tempering method to achieve rapid convergence. Synthetic tests and application to an OBS installed at the Yamato Basin, the Sea of Japan, show that the proposed method can estimate radial‐component Green's functions more accurately than conventional receiver function methods. We suggest that the high‐frequency Green's functions estimated by the new method can be used to reveal fine‐scale (in order ~100 m) structure of the seafloor sediment.

Marine Sediment Characterized by Ocean‐Bottom Fiber‐Optic Seismology

“…For geotechnical applications, such as the construction of offshore platforms and pipelines, these models provide constraints on the shear modulus (Ayres & Theilen, 2001) and allow quantifying sediment stability and earthquake amplification effects (Akal & Berkson, 2013; Sanchez‐Sesma, 1987). For seismic imaging, shear‐wave velocity models are required to improve the processing algorithms for multicomponent seismic data like static correction for converted PS waves (e.g., Muyzert, 2000), wavefield separation (e.g., Schalkwijk et al, 2000), or other imaging techniques with phase conversion (e.g., Akuhara et al, 2019). Also, combination of both S and P wave velocities helps to better interpret the lithology because together they are much more sensitive to fluid and gas contents than P wave alone (Ayres & Theilen, 2001).…”

Overpressured Underthrust Sediment in the Nankai Trough Forearc Inferred From Transdimensional Inversion of High‐Frequency Teleseismic Waveforms

“…This is due to intense water reverberations dominating the vertical component records. Recent efforts have overcome this difficulty and allowed for investigating subsurface structure using high-frequency receiver functions with data from offshore observatories (Akuhara et al, 2016(Akuhara et al, , 2017(Akuhara et al, , 2019.…”

“…This study performs the two-step teleseismic waveform inversion for stations from the seafloor cabled network (DONET1) deployed at the Kumano-nada (Kumano Sea) in the central Nankai subduction zone. First, we calculate high-frequency GFs using the multichannel deconvolution (MCD) method (Akuhara et al, 2019). Then, the GFs are inverted for the one-dimensional (1-D) seismic velocity structure beneath each station.…”

Joint Inversion of Rayleigh Wave Phase Velocity, Particle Motion, and Teleseismic Body Wave Data for Sedimentary Structures

“…Both surface wave and body wave (BW) data have been used in resolving sedimentary structures beneath seismic stations. For example, the amplitude ratio of Rayleigh wave recorded by the vertical and radial components, known as the Z/H ratio, is very sensitive to sedimentary structures (e.g., Boore & Toksöz, 1969) and has been used to invert for sedimentary structure (e.g., Lin et al, 2012, Li et al, 2016 teleseismic P waves are another type of data that are sensitive to the velocity jump at the sediment base and have been used to invert for sediment thickness and velocity (Akuhara et al, 2019;Bao & Niu, 2017). A recent study (Phạm & Tkalčić, 2017) suggests that autocorrelation of the teleseismic P wave coda is a promising technique for mapping shallow seismic boundaries.…”