with(plots):
animate3d((1-2*abs(1-t))*x*exp(-x^2-y^2),
    x=-3..3,y=-3..3,t=0..2,frames=20);

1. The peak and valley of the surface are extended by multiplying by a parametrized function that takes values from -1 to 1, and then back to -1.  Maple's "animate3d" command does the rest!
2. If this animation will be viewed by a fairly fast computer, you will need to use an animation editor to slow down the resulting GIF file; otherwise, the pumping action of the surface may be distractingly fast.  The image above has been edited so that each frame is displayed for 0.15 seconds.