Couldn't be simpler...
Add Warpradial FX either to your layout or the layer you wish to affect.
Set the values to.
*Frequency: 5
Amplitude: 3
Speed: 50*
The best way to activate and deactivate is simply query whether any explosions are on screen and enable and disable accordingly. As per the code below.
[img=17079]
One of the tweaks I'll be making will be to alter the values to match the intensity of the explosion.
Check out the awesome effect below, with which I also used Scanlines to match the style of game... being that of a terminal.