Effects of Thermal Cracks on the Seismic Anisotropy of Oceanic Lithosphere

Abstract

Thermal cracks are a natural consequence of cooling in the oceanic lithosphere, yet their potential influence on seismic anisotropy has remained underexplored, in part because of the difficulty of treating arbitrarily oriented cracks in anisotropic media. Here we use a new computational framework to investigate how thermal cracks modify elastic properties, with particular emphasis on radial and azimuthal anisotropy. We find that even modest crack populations can appreciably alter effective elastic properties and generate distinct anisotropic signatures that depend strongly on crack geometry, orientation, and spatial distribution. These effects are particularly pronounced in the shallow lithosphere, where confining pressure is low. No single anisotropy measurement is unique to thermal cracking, but the predicted period dependence and the joint behavior of radial anisotropy, surface‐wave azimuthal terms, and shear‐wave splitting provide testable constraints. Such observations, especially when combined with attenuation, scattering, electrical, and seafloor‐structure data, may constrain the mechanical state of oceanic plates and the conditions that enable plate tectonics.