Today’s psalm forms a chiastic structure:
1a) Psa 46:1, God our refuge + present help in trouble;
1b) Psa 46:2-5, We will not fear though the earth be removed;
1c) Psa 46:6, The nations raged + the kingdoms were moved when He uttered His voice;
central axis) Psa 46:7, The LORD of Hosts is with us, the God of Jacob is our refuge;
2c) Psa 46:8-9, The works of the LORD + He makes wars to cease and breaks the bow;
2b) Psa 46:10, Be still, and know that I am God;
2a) Psa 46:11, LORD with us + God our refuge.
How can we not be afraid, when everything is going to rack and ruin around us? By knowing that the LORD is God (the B pair). Knowing who God is, and what it means that He is God, He alone is God, and beside Him there is no other (Deu 6:5). Knowing His nature, His character, and His plan.
Moreover, the 1b element itself forms its own chiastic structure (I am beginning to see this in the Psalms: smaller structures embedded within the larger one):
1a) Psa 46:2a, Therefore we will not fear, even though the earth be removed;
1b) Psa 46:2b-3, The mountains carried in the midst of the sea;
central axis) Psa 46:4a, There is a river whose streams shall make glad the city of God;
2b) Psa 46:4b-5a, The holy place of the tabernacle, God is in the midst of her;
2a) Psa 46:5b, She shall not be moved, for God will help her.
The A pair reveals that even if the earth is moved, but the city of God will not be moved. So we do not need to fear, because God will help us.
The B pair reveals that even as the mountains end up in the midst of the sea, the LORD God remains in the midst of His city, in the midst of the Holy Place of His tabernacle. Scripture is making a contrast between chaos (the earth, i.e., the kingdoms of this world) and complete and utter stability (the city of God, the kingdom of heaven).
The central axis is about the river whose streams make glad the city of God. So the picture that is being painted, is the river in the midst of the city. Ezekiel has a vision in which the river flows through the midst of the city, issuing out from under the temple (Eze 47:1-12). John also has a vision in which the river flows through the midst of the city, issuing out from under the throne of God (Rev 22:1-5). I think Ezekiel and John are seeing the same thing, and Psa 46 is prophesying of it.
Of course, I believe the river to be the rivers of living water, which Jesus our Lord provides freely to all those who are thirsty!