KM3NeT-ORCA is a water-Cherenkov neutrino detector designed for studying the oscillation of atmospheric neutrinos, with the primary objective of measuring the neutrino mass ordering.
Atmospheric neutrinos crossing the Earth undergo matter effects, modifying the pattern of their flavour oscillations. The study of the angular and energy distribution of neutrino events in ORCA can therefore provide tomographic information on the Earth's interior with an independent technique complementary to the standard geophysics methods.

This contribution presents an updated study of the potential of ORCA for Earth tomography, based on a full Monte Carlo simulation of the detector reponse and including systematic effects related to oscillation parameters, neutrino flux, cross-sections and detector performance, as well as possible degeneracies in the density measurement of different layers. Results show that after ten years of operation the proposed ORCA detector can measure the electron density with a precision of 5 to 6\% in the mantle and 6 to 9\% in the outer core -- depending on the mass ordering.