fireworks display during nighttime

Each year I sit on the shore of Woodbridge South Lake to take photos of the annual Independence Day fireworks. My basic technique is to point a tele lens on a tripod at where the fireworks will appear, and take a lot of 10 second exposures, using a self-timer to avoid any shutter jiggle. Out of the 30 or so images, usually a few are special. This year, it was this one.