on Apr 12, 2014 at 2:21:06 pm Last Edited By Erik Anschicks on Apr 13, 2014 at 9:18:45 pm
On a large budget, the most common way through my experience is gear called Lightning Strikes, though I'm not certain if that's the actual company name. It produces a controllable burst of light from the lamp head that can go up to about 250K worth of blast! I've also seen it used to simulate blast from explosions. Not sure about other similar brands/products, that's the only one I've ever seen in actual on-set use.
A lower-budget way is to get a few strong still-photo heads and synchronize them to varying degrees. We did this with about 5-8 Profoto heads on a country music video for Josh Turner a few years ago that needed to simulate the the look of fireworks.