Not all termites are pests, so it may save you a lot of money to find out what type you have.
You shouldn't disturb anything until you really have to as these days a group of feeding termites can make control easier.
A month is very quick. They were probably already there and have just moved up to take advantage of the mulch. That may be a bad thing if they area pest type. Why were they already there, ready to exploit the mulch? You should have your house inspected by a competent inspector and get a written report and pest identification. Then you can decide how to progress.
It is quite common for termites to feed within a house for several years before making any obvious signs of their presence. That's why you need a good inspector. Modern tools like a Termatrac, thermal image camera and moisture meter can help.
