  We consider the $2\to 2$ scattering amplitude of identical massive particles.
We identify the Landau curves in the multi-particle region $16m^2 \leq s, t <
36m^2$. We systematically generate and select the relevant graphs and
numerically solve the associated Landau equations for the leading singularity.
We find an infinite sequence of Landau curves that accumulates at finite $s$
and $t$ on the physical sheet. We expect that such accumulations are generic
for $s,t > 16m^2$. Our analysis sheds new light on the complicated analytic
structure of nonperturbative relativistic scattering amplitudes.
