So, Thor's Map allows you to switch to make a location the active location as a travel action.

My question is, does this overlap with the traditional travel action?

Could I, for example, use Thor's map to travel to a location, immediately clear it, and then elect to travel to a different location normally ?

The action window in the Travel phase comes after the normal decision of whether to travel. So your example would not work, but you could do it the opposite way round. Travel to a location normally, immeciately clear it, then use Thror's Map to travel to another location.