'Anger' in the Bible

Who can tell if God will turn and repent, and turn away from his fierce anger, that we perish not?

And he prayed unto the LORD, and said, I pray thee, O LORD, was not this my saying, when I was yet in my country? Therefore I fled before unto Tarshish: for I knew that thou art a gracious God, and merciful, slow to anger, and of great kindness, and repentest thee of the evil.