Normally , these type of stratovolcanoes generate explosive Plinian eruptions with associated pyroclastic flows that can melt snow and glaciers near the summit , thus producing devastating lahars . As is the case for many subduction-zone volcanoes , Nevado del Ruiz can generate explosive Plinian eruptions with associated pyroclastic flows that can melt snow and glaciers near the summit , producing large and sometimes devastating lahars ( mud and debris flows ) .