In case this is unclear to anyone; all transonic, supersonic, or hypersonic flight/movement causes a 'continuous' sonic boom. A Bell X-1 at Mach 1.06 causes a continuous sonic boom along it's path, as does a Mach 2 Concorde and a Mach 2.6 Browning 50 cal machine gun bullet. "Sonic booms" are not discrete events that occur when you cross the 'sound barrier' or continuous when you stay at it. They are continuous at it and past it, not stopping until your velocity drops down below it again.
GIF that does a good job of explaining this: http://upload.wikimedia.org/wikipedia/commons/e/e4/Doppleref... That leading edge where all the circles are kind of meeting up? That is where the sonic boom is. It continuously sweeps across the landscape behind the source, as long as the source is moving faster than the speed of sound.
Going faster tightens that pressure wave cone, but there are a lot of other factors too. Vehicle geometry seems to be a pretty dominating factor for example, longer aircraft have less severe sonic booms. Depending on the shape of your aircraft you may or may not get several shockwaves originating from different points that after a distance combine to form a larger shockwave. Altitude is a biggie too, the higher you are the less intense it will be.
GIF that does a good job of explaining this: http://upload.wikimedia.org/wikipedia/commons/e/e4/Doppleref... That leading edge where all the circles are kind of meeting up? That is where the sonic boom is. It continuously sweeps across the landscape behind the source, as long as the source is moving faster than the speed of sound.