18:6 seems to imply that God has a heavenly throne. Revelation expands on that. God is in the violent forces of nature. Is the earthquake a response to God's anger. Then we have a word picture of God riding on a cherub. I think flying chariot.
A book I have recently read is called "He Shall Thunder from the Sky". Perhaps that is an allusion to 18:13. The God who get the rocks to moving is a God who is very close indeed. He is very involved in his world. He starts in his temple (on earth or in heaven). Then he gets busy. I wonder if the author experienced an awful earthquake. It reminded him of God's awesome power. The earthquake is a response to a small ripple of God's anger. The breath from his nose can cause a great earthquake (18:15).
Then God shows his involvement with his people. God is described as a redeemer, a deliverer. I am reminded of how much God wants to be involved in our lives. When we are in trouble he wants us to cry out to him. "He rescued me because he delighted in me." (18:19)
Verse 20 is a promise. Is it for me? Am I qualified? Am I righteous or clean enough? Thank God I do have a redeemer in Jesus Christ who has made me righteous. Verses 20 and 24 are bookends enclosing a promise and a challenge. Can I walk blameless before him? Can I live righteously? I have been made clean by God's mercy. And God expects us to strive to live a life worthy of our calling.
Keep reading Psalm 18. It bears reading slowly and rereading. There is good stuff here.