Einen geliebten Mensch zu verlieren, hinterlässt tiefe Wunden.
Why is hinterlassen used here instead of verlassen? Is hinterlassen more formal than verlassen?
Verlassen means to go away [from a place/someone/something].
Hinterlassen emphasizes that you leave something/someone behind while going away. It puts focus on the object/person left behind.
It is often used when someone dies and leaves something/someone behind or bequeathes something to someone.
However, it can also be used when someone alive intentionally leaves something behind:
However, you would never use hinterlassen if someone simply forgets to take something with him. For example if you said »Er hat seinen Schlüssel hinterlassen«, it would emphasize that he left his keys with intention. Otherwise you would say: »Er hat seinen Schlüssel vergessen.«
You can also leave an impression:
Important: If the object of hinterlassen is a person, it will always sound as if this person was left behind by somebody who has died.
You can find more examples here: http://www.duden.de/rechtschreibung/hinterlassen_vererben_zuruecklassen
No, "verlassen" is an action, it means "to leave someone/something". "Hinterlassen" means "to leave someone/something behind". That's a very different thing.