According to IE website SVG is supported. And according to this answer too What are SVG (Scalable Vector Graphics) supported browsers?
http://jsfiddle.net/jitendravyas/2
The problem is that you are using percentages for height and width, as explained here (http://www.seowarp.com/blog/2011/06/svg-scaling-problems-in-ie9-and-other-browsers/).
If the width and height are either defined as something as useless as 100% or if they aren’t defined at all, these browsers will make a guess as to what the dimensions ought to be based on the points and shapes defined in the body of the SVG file.
Change to width=480
and height=360
and you should be fine.