About the meaning of による (cause or dependency?)


I usually see による used as a way to express the cause of something:

> 震災によってたくさんの人の命が失われた。  
>  There were many people who lost their lives due to the earthquake.

But in some places I see it being used as a way to express dependency on
something:

> すべてはそれによるね  
>  Everything depends on it.

How can I differentiate between those uses?

