New Terra was dormant when they arrived. When eden started terraforming that's when problems started.
1.
Volcano - When the blight began to break down the crust, it gave the underlying magma a way to escape. Thus we have volcanos.
2.
Earthquake - Again. From the blight. The blight broke down some rock from the fault line, which caused the firm structure to be able to move more freely. The plates would become caught on each other, causing tension. Soon, the elasticity of the rock was overcome, causing it to break. Large amounts of energy were released, causing earthquakes.
3.
Lighting Storm - The release of gas from the magma caused a medium for the storms to travel on. Due to lack of moisture in other parts of the atmosphere, there was increased static electricity, causing lightning.
4.
Vortex - Almost the same as the storms, but when a low and high pressure zone occur along a border, the zones slowly shift locations. It speeds up causing tornadoes!
5.
Meteorite - This one is a real natural disaster, but even we on earth cope with it. It's more durastic on New Terra, due to the lack of a thick atmosphere