The nomads were terrified. For a week the ground had shuddered violently. Cracks opened up in the soil swallowing goats and camels. Sulphur-laced smoke rose out of the dark slits. After retreating to the hills, the nomads saw chunks of obsidian rock burst through the Earth's crust "like huge black birds" and fly 30 metres into the air.With this kind of violent geologic activity and without any scientific knowledge, I, too, would be fairly certain that the gods were angry. But it wasn't a righteous god or a movie's special effects... the nomads in Ethiopia's Afar region were witnesses to seismic activity that will eventually lead to the birth of an ocean and the loss of Africa's horn.
A mushroom cloud of ash dimmed the sun for three days. At night the new crater breathed flashes of fire.
While on the topic of earth science, take a look at these photographs of the earth from space and if you happen to visit the British Museum, there's a collection of Georg Gerster aerial photographs that show how man has made a very visible mark on this planet.