Earth's crust has been slowly moving for billions of years. Not only mountains are slowly moving but also whole continents. The Quran says that mountains move:
[Quran 27.88] You see the mountains and think they are firmly fixed: but they are moving away just like the clouds are moving away: (such is) the artistry of Allah, Who disposes of all things in perfect order: for He knows all what you do.
How could an illiterate man who lived 1400 years ago have known that mountains move?
Earth's crust is full of cracks and fault lines. This was only known recently. However the Quran said that Earth had cracks 1400 years before it was discovered:
[Quran 86.12] And the Earth that has cracks.
How could an illiterate man who lived 1400 years ago have known that Earth has cracks?
Some planets are all gas like Jupiter, others are all liquid. In such planets you do not have a foothold. However Earth has solid rock. Mountains are made of solid rock (not gas or liquid).
[Quran 16.15] And He cast mountains on the earth, lest it shifts with you; and rivers, and roads, so that you may be guided.
Mountains are made of solid rock so that it doesn't slide like other planets. You don't have landmarks to guide you in a gaseous planet.
Valleys form with vertical cracks sliding downwards while mountains form with vertical cracks moving upwards. The vertically moving sections preventing lateral sliding of the surface.
How could an illiterate man who lived 1400 years ago have known that mountains prevents surface sliding?
In earthquakes most of the energy is released by the mainshock (first quake). The rest of the energy is released by the following weaker aftershocks. The Quran describes both of them:
[Quran 79.6-7] On the day when the earthquake shakes, followed by the successor
How could an illiterate man who lived 1400 years ago have known that mainshocks are followed by aftershocks?
(The Christian Bible says that Earth is fixed on top of pillars 1 Samuel 2:8)