Mathematica code:
Animate[
Graphics[
Table[
{Thickness[.006],
Circle[{(16 - t)*Cos[i*Pi/2], (16 - t)*Sin[i*Pi/2]},
(100 - n) (1 + Sign[100 - n])/2]}, {n, 0, 100, 1},
{i, 0, 3, 1}],
PlotRange -> 40, ImageSize -> 700],
{t, 0, 2.6, .2}]
(via laplumeabelle)