We compute the radiative ro-vibrational emission spectrum of H2 involving quasibound states via a simple numerical method of resolution of the Schrödinger equation by introducing a modifed effective molecular potential. The comparison of the eigenvalues obtained with our approximation and other theoretical methods based on scattering resonance properties is excellent. Electric quadrupole and magnetic dipole contributions are calculated and we confirm the previous computations of Forrey of the electric quadrupole transition Einstein coeffcients. The astrophysical relevance of such quasibound levels is emphasized