Catastrophea
Catastrophea was the second name of the planet originally named Kastopheria after its discoverer, Elias Kastopherious. By the time that the Third Doctor and Jo visited the planet, it was almost exclusively called "Catastrophea", and its capital city was Catastrophea City.
Physical geography
It had a temperate, subtropical climate and was incredibly fertile. Though possessed of no minerals to speak of, it did grow a variety of exotic fruits and rare medicinal plants. This fecundity proved a double-edged sword, bringing both bounty and tragedy to the planet.
Why the name changed
After Kastopherious discovered the planet, human colonisation came slowly. When it did, the humans discovered that the natives were pliable. They were apparently happy being farmhands. Eventually, the human colonists sold out to the Kastopheria Company. All the humans became wealthy, but, reduced to the role of overseers, they turned on the native population. Since their wealth was now tied to hitting productivity targets imposed by the company, they began to mistreat the natives in an effort to get them to work more.
Over time, some of the agricultural land was turned to growing more dubious drugs. The mild, somewhat-legal Jokkarta and the harder, absolutely illegal skar — which Jo Grant called "a cross between LSD and cocaine — were grown on the planet.
Eventually, Earth received word of the planet's woes. A number of charitable and religious missions followed, with a goal of putting the colony back on a path of reasonable development. These missions sent reports back to Earth, which led the President of Earth to call the situation on Kastopheria "a catastrophe waiting to happen". People then began calling the planet "Catastrophea" and the name soon stuck.