That would be quite involved 🙂 But doable. You’d need to add_rewrite_rule()
to create rewrite rule which points to a query for events with tag equal to music and venue equal to planet-earth.
Unless you have a small number of both venues and tags, you might want to decide on a structure /my/event/structure/[venue]/[tag]
or /my/event/structure/[tag]/[venue]
so you don’t have to manually create a rewrite rule for each tag-venue pair.
If pretty permalinks isn’t important, you can do: /events/event/?event-tag=music&event-venue=planet-earth
.