In this work, the surface melt dynamics of amorphous Si films on glass was investigated experimentally and numerically for long pulse duration (200 ns) excimer laser crystallization. The melting threshold, melt duration, depth of fusion and critical fluence corresponding to the SLG regime were characterized by time-resolved reflectivity measurements, scanning electron microscopy and Raman spectroscopy. The numerical analysis of the laser melting-solidification process, including the explosive recrystallization phenomenon, was demonstrated to be consistent with the experimental results.