  We consider the Cauchy problem for the wave equation in $\Omega\times{\mathbb
R}$ with data given on some part of the boundary $\partial\Omega\times{\mathbb
R}$. We provide a reconstruction algorithm for this problem based on analytic
expressions. Our result is applicable to the problem of determining
nonstationary wave field arising in geophysics, photoacoustic tomography,
tsunami wave source recovery.
