In Revelation 10:3-4 the 7 thunders are talked about. Are these anywhere else in the Bible or is there any explanation for this?
The Seven Thunders of Rev.10 are most probably an unknown pronouncement of God between the 6th and 7th Trumpets. John was about to record this for us when the Lord told him not to (Rev. 10:4).
While they’re not specifically described anywhere else in Scripture, there is an interesting passage in Psalm 29 where the voice of the Lord is mentioned seven times and is compared to the sound of thunder. (Psalm 29:3-9). The name of the Lord is given four times in the two verse introduction of the Psalm and four times more in the two verse conclusion (four is the number of Creation). It appears ten times in verses 3 through 9 (ten is a number that denotes the completeness of Divine Order) and the phrase “Voice of the Lord” is repeated seven times (seven is the number of perfection). This passage is often called “the Seven Thunders of God.”
With the Seventh Trumpet, we’re told that the Kingdoms of the world have become the Kingdom of our Lord (Rev. 11:15) and for the first time the traditional translation of God’s name as “the One Who is and Who was and Who is to come” is changed to just “the One Who is and Who was” (Rev. 11:17) also indicating that His reign has begun. (Some translations put the “Is to Come” part back in but the Greek text doesn’t include it.)
This means that in the Heavenly view, the Great Tribulation has begun. After Satan’s losing battle in Heaven and confinement to Earth in Rev. 12, the anti-Christ makes his official appearance on Earth as Satan’s host at the beginning of Rev. 13. (He first came on the scene in Rev. 6 as a mere man.) This signals the start of the Great Tribulation on Earth. The seven Bowl judgments begin soon thereafter.
Put all this together and you can make a circumstantial case that the Seven Thunders announce that the coming Bowl Judgments will complete the Divine Order, perfectly satisfying God’s righteous requirement that the people of Earth be judged for their sins, leaving Earth in a condition of readiness to receive her King.