Wide-angle, full waveform inversion with a sparse ocean-bottom seismometer dataset, imaging the Cyprus Arc from the Eratosthenes Seamount to the Hecataeus Rise.

Abstract

Tectonophysicists working with wide-angle seismic reection and refraction data generally rely on tomographic inversion and forward modelling techniques to produce P-wave velocity models of the subsurface. Only recently, researchers have produced high-resolution P-wave velocity models using full-waveform inversion (FWI). However, they use ocean-bottom seismometer (OBS) datasets with a dense instrument spacing. This study revisits a sparsely acquired OBS dataset from the geologically complex Eastern Mediterranean to explore the feasibility of applying FWI to such a dataset. With frequency domain viscoacoustic FWI, we observe an adequate decrease in the objective function, suggesting that a high-resolution velocity model for the upper 15 km is obtainable through FWI with a typical OBS dataset. This decrease in the objective function does not preclude convergence to a local minimum. The recovered FWI model suffers from uncertainties in the starting model related to a complex geological environment. Cognizant of model uncertainties, we interpret an accretionary prism between the southern Eratosthenes continental block and the northern Hecataeus Rise from the final FWI model.