Receiver Function Deconvolution with Noisy Seafloor Seismic Data: Amplifying Conversions from the Lithosphere

Session: Ocean Bottom Seismology – New Data, New Sensors, New Methods [Poster]
Type: Poster
Date: 4/30/2020
Time: 08:00 AM
Room: Ballroom
Description: 

The seismic structure of the normal oceanic lithosphere is pivotal to our understanding of global geodynamics and plate tectonics. However, the seafloor is a challenging environment for lithospheric imaging using source-deconvolution methods, e.g., receiver functions (pRFs). This is because it is difficult to identify earthquake signals buried in data obtained from seafloor seismic stations sitting at the fluid-solid interface which is continuously recording acoustic waves generated from a variety of other processes in the overlying ocean layer. Additionally, reverberations from an underlying fluid-saturated sediment layer make inferences on deeper lithospheric layers difficult. In this study, we address this and other challenging factors that hamper signal detection from deeper crustal and mantle conversions recorded on seafloor seismic data. We process earthquake records from the NoMelt experiment located on mature (~70Ma) Pacific seafloor. We apply multiple techniques targeted at improving the signal detection necessary for further receiver function analysis. After correct rotation and multi-spectral analysis, we obtain a total number of 1,084 high-quality records (SNR>1.5) from 22 stations. Preliminary results following source-deconvolution show that the sedimentary layer reverberations have a significant impact on the raw receiver function stacks, making inferences of deeper crust or lithospheric layering unreliable. In order to suppress the offending reverberations, we use the joint inversion of apparent polarization, coherence peaks and pRF auto-correlation to estimate near-surface shear wave velocity. We then apply a resonance removal filter to eliminate its imprint on the RF stacks. With these appropriate corrections, stable high-resolution body-wave imaging of the lithosphere can be conducted with sea-floor stations and used to supplement long-wavelength surface wave studies for testing models of oceanic plate origin and evolution.

Presenting Author: Ziqi Zhang

Authors