Translation of the verse 1 from Surah Az-Zalzalah : Number of verses 8 - - page 599 - Part 30.
When the earth is shaken with its (final) earthquake.
When the earth is shaken with its [final] earthquake
(99:1) When the earth will be shaken with a mighty shaking, *1
*1) Zalzalah means to shake violently over and over again. Thus, zulzilat-il,ardu means that the earth will be shaken violently by convulsion after convulsion, and since shaking of the earth has been mentioned, it automatically gives the meaning that the entire earth will be shaken and not a limited territory of it. Then, in order to express the great intensity of the earthquake the word zilzalaha has been added, which literally means "its being shaken". It mean: "It will be so shaken as a huge sphere like it ought to be shaken, or shaken to its utmost intensity." Some commentators have taken it to imply the first earthquake with which the first stage of Resurrection will begin, i:e. when all living beings will perish and the present order of the world will be upset. But, according to a large section of them, ii implies the earthquake with which the second stage of Resurrection will begin, i. e. when all the former and the latter generations of mankind will rise back to life. This second commentary seems to be more correct, for the whole subsequent theme supports it.
Source : Az-Zalzalah Verse 1: When the earth is shaken with its [final] earthquake