Are earthquakes and disasters that claim many lives a divine decree or natural phenomena, taking into account that "Allah Almighty is merciful to His servants" and "What is with Allah is better for you, if only you knew"?

Allah's knowledge encompasses everything in the universe. Verses have shown that He knows the unseen of the heavens and the earth, and that no leaf falls but with His knowledge, nor is hidden from Him the weight of an atom. Allah already knows the lifespan of every human, the end of their term, and the cause of their death, whether it be due to an earthquake or anything else. An earthquake is but one of Allah's soldiers, with which He tests whom He wills. Nature has no effect except by the will and decree of Allah Almighty.