Hi Donna ,

 THE EZEKIEL 38:18-19 EARTHQUAKE :

"And it shall come to pass at that same time when Gog shall come against the land of Israel ......Surely in that day there shall be a great shaking in the land of Israel."

I believe that the earthquake event of Ezekiel 38:18-19 is the VERY SAME  earthquake event that is described in Revelation 6:12 :

"And I beheld that when He had opened the sixth seal , and lo, there was a great earthquake......" 

I believe these are ONE AND THE SAME earthquake because I believe that seals #2 , #3, and #4 are describing the Gog-Magog War against Israel.

THE SEVENTH ANGEL'S EARTHQUAKE :

The following earthquake descriptions are BOTH of the very same earthquake because they are BOTH described as a part of the seventh angel's  events :

Revelation 11:15-19  "And the seventh angel sounded..... and there were lightnings, and voices , and thunderings , and an earthquake ....and great hail."

Revelation 16:17-18  "And the seventh angel poured out his vial......and there were voices, and thunders, and lightnings , and there was a great earthquake...a great hail."

THE TWO WITNESSES EARTHQUAKE :

Revelation 11:12-15  "And they ascended up to heaven in a cloud......And the same hour there was a great earthquake...the second woe is past......And the seventh angel sounded.." 

Therefore ,  because  the Two Witnesses earthquake CAME JUST BEFORE  the seventh angel sounded it was a completely different earthquake.

Blessings to you.