He looketh on the earth, and it trembleth - There is great sublimity in this expression, as indicating the power and the majesty of God. He has only to "look" upon his works, and they stand in awe and tremble. The most mighty and fearful convulsions of nature occur as if they were the mere effect of God's "looking" on the earth. Compare Habakkuk 3:10 - "The mountains saw thee, and they trembled."
He toucheth the hills, and they smoke - That is, as Mount Sinai did when God came down upon it. Exodus 19:18. It is as if the hills were conscious of his presence, and were awed.

He looketh on the earth - Even the look of God terrifies all created nature!
He toucheth the hills - So easy is it for God to burn up the earth and the worlds thereof, that even his touch kindles the mountains into flames! See Etna, Vesuvius, Stromboli, etc.; these are ignited by the touch of God. How majestic are these figures!
The renewal of the earth, and re-creation of deceased animals, shall take place when he shall shake terribly the heavens and the earth; when they shall be wrapped together as a scroll, and the earth and its works be dissolved, that is, after the general convulsion and conflagration of the world.

He looketh on the earth, and it trembleth: he toucheth the hills, and they (r) smoke.
(r) God's merciful face gives strength to the earth, but his severe countenance burns the mountains.

He looketh on the earth, and it trembleth,.... As Sinai did when he descended on it, Psalm 68:8, to which the allusion seems to be; and a look from him, a severe one, a frowning one, will make the inhabitants of the earth to tremble; a providential look, sending famine, pestilence or the sword among them. A displeased look will make the hearts of his own children tremble, as no doubt Peter's did, when the Lord looked upon him, and he remembered his word; and if a look, much more a word, an awful word, as his voice in the law, pronouncing such cursed as keep it not; and especially the tremendous sentence he will pronounce on the wicked at the last day,
go, ye cursed, &c. and if a look and a word are so terrible, what will be the lighting down of his arm, with the indignation of his anger upon those who have refused to give him glory? For the words seem to carry in them a reason why he should be glorified, taken from the consequence of not glorifying him, who has such a majesty in his looks, such a terror in his countenance, and such power in his hands.
He toucheth the hills, and they smoke; as Sinai likewise did, when he was upon it, Exodus 19:18, and as other hills do, when touched with lightning; the tops of mountains, the higher they are, the sooner and the more they smoke (u). God, with a touch of his hand, can set mountains on fire, open "volcanos", and cause them to burn for years together; as Etna, Vesuvius, Hecla, and others: and how easily can he set on fire the course of nature, burn the world, and all that is in it! It is but touching it, and it takes fire immediately: this he can as easily do as a man can light a torch or a candle; and as easily can he destroy sinners with the fire of his wrath, or cast them into everlasting fire, with the devil and his angels, which will burn to the lowest hell; and what are hills and mountains, or the greatest personages on earth, if he does but touch them, or lay his hand upon them in wrath? They are crushed as the moth; they are nothing before our great Zerubbabel.
(u) "Montis vicina cacumina coelo----Tanto "magis edita fumant", Lucret. de Rerum Natura, l. 6. v. 458, 459.

He looketh - This is a farther illustration of God's powerful providence: as when he affords his favour to creatures, they live and thrive, so on the contrary, one angry look or touch of his upon the hills or earth, makes them tremble and smoke, as Sinai did when God appeared in it.