How to create event: "User adjusts its location in drop down list" using a drop down list in a created block ?

Hello!

I would like to do the following:
1/ create a block with a drop down selection list with a list of taxonomy terms (corresponding to locations)
2/ when the user updates the value in this dropdown selection, it would generate an event, and pass the selected term
3/ then a rule would be created using this event: when it happens, it would trigger an action to redirect the user to a page .../selectedlocation

I think i can do 3/ with rule.. would you know how i can do 1/ and 2/ or of any related documentation? Or do you think of a better way to do it than with rules?

Any help much appreciated.
Thanks,

Matthieu