Fiber-Optic Sensing (DAS)

A fiber-optic cable measures axial strain, i.e. the in-line (radial) component of Rayleigh-wave motion, not the vertical motion recorded by geophones. Under strong velocity contrasts or velocity reversals, radial and vertical dispersion trends can differ. Radial-component predominant-mode (RCPM) inversion matches DAS dispersion data with the mode carrying the maximum radial modal participation, accounting for source-receiver directivity.

 ✅Component-consistent forward model for DAS data

 ✅No explicit modal indexing, less analyst subjectivity

 ✅Tested on three synthetic models and two field DAS datasets

 ✅Vs profiles agree with independent borehole measurements

Ref: Bhaumik & Cox (2026), JGR: Solid Earth (accepted)