The 6th Trumpet is described in detail by Joel.
6th Trumpet (Rev 9):
[SUP]13 [/SUP]Then the sixth angel sounded: And I heard a voice from the four horns of the golden altar which is before God, [SUP]14 [/SUP]saying to the sixth angel who had the trumpet, “Release the four angels who are bound at the great river Euphrates.” [SUP]15 [/SUP]So the four angels, who had been prepared for the hour and day and month and year, were released to kill a third of mankind. [SUP]16 [/SUP]Now the number of the army of the horsemen was two hundred million; I heard the number of them. [SUP]17 [/SUP]And thus I saw the horses in the vision: those who sat on them had breastplates of fiery red, hyacinth blue, and sulfur yellow; and the heads of the horses were like the heads of lions; and out of their mouths came fire, smoke, and brimstone. [SUP]18 [/SUP]By these three plagues a third of mankind was killed—by the fire and the smoke and the brimstone which came out of their mouths. [SUP]19 [/SUP]For their power is in their mouth and in their tails; for their tails are like serpents, having heads; and with them they do harm.
Compare to Joel 2:
Blow the trumpet in Zion,
And sound an alarm in My holy mountain!
Let all the inhabitants of the land tremble;
For the day of the Lord is coming,
For it is at hand:
[SUP]2 [/SUP]A day of darkness and gloominess,
A day of clouds and thick darkness,
Like the morning clouds spread over the mountains.
A people come, great and strong,
The like of whom has never been;
Nor will there ever be any such after them,
Even for many successive generations. [SUP]3 [/SUP]A fire devours before them,
And behind them a flame burns;
The land is like the Garden of Eden before them,
And behind them a desolate wilderness;
Surely nothing shall escape them.
[SUP]4 [/SUP]Their appearance is like the appearance of horses;
And like swift steeds, so they run.
[SUP]5 [/SUP]With a noise like chariots
Over mountaintops they leap,
Like the noise of a flaming fire that devours the stubble,
Like a strong people set in battle array.
[SUP]6 [/SUP]Before them the people writhe in pain;
All faces are drained of color.
[SUP]7 [/SUP]They run like mighty men,
They climb the wall like men of war;
Every one marches in formation,
And they do not break ranks.
[SUP]8 [/SUP]They do not push one another;
Every one marches in his own column.
Though they lunge between the weapons,
They are not cut down.
[SUP]9 [/SUP]They run to and fro in the city,
They run on the wall;
They climb into the houses,
They enter at the windows like a thief.
[SUP]10 [/SUP]The earth quakes before them,
The heavens tremble;
The sun and moon grow dark,
And the stars diminish their brightness.
[SUP]11 [/SUP]The Lord gives voice before His army,
For His camp is very great;
For strong is the One who executes His word.
For the day of the Lord is great and very terrible;
Who can endure it?
Putting it all together we now know that the Army of the Lord is 200 million strong. We know that they kill 1/3 of the earth. We see that the 6th seal and 6th trumpet are linked to Mat 24:29-31 and Rev 19.
