  Atmospheric neutrinos provide a unique avenue to explore the internal
structure of Earth based on weak interactions, which is complementary to
seismic studies and gravitational measurements. In this work, we demonstrate
that the atmospheric neutrino oscillations in the presence of Earth matter can
serve as an important tool to locate the core-mantle boundary (CMB). An
atmospheric neutrino detector like the proposed 50 kt magnetized ICAL at INO
can observe the core-passing neutrinos efficiently. These neutrinos would have
experienced the MSW resonance and the parametric or neutrino oscillation length
resonance. The net effect of these resonances on neutrino flavor conversions
depends upon the location of CMB and the density jump at that radius. We
quantify the capability of ICAL to measure the location of CMB in the context
of multiple three-layered models of Earth. For the model where the density and
the radius of core are kept flexible while the mass and radius of Earth as well
as the densities of outer and inner mantle are fixed, ICAL can determine the
location of CMB with a 1$\sigma$ precision of about 250 km with an exposure of
1000 kt$\cdot$yr. With the 81-layered PREM profile, this $1\sigma$ precision
would be about 350 km. The charge identification capability of ICAL plays an
important role in achieving this precision.
