Ooops! Big clarification. I do not know if the park will be open at night at all. Hell, I didn't know about the waterfalls or viewing deck until today! At this point, I am sitting here just like all of you guessing and wondering. The lit water was something I have been dreaming about, but only from the top... I have no actual knowledge of what the volcano will do at night.
This was a picture I sent to a "friend" months ago dreaming of such eruptions from the top.