Natural cause
From semanticweb.org
The natural cause of an event such as an earthquake or volcanic erruption.
An example of an agent as defined by the OntoCleanPaper.
It is a little difficult to be specific as many things are agents which cause something while being caused by something else.
Example
Circulation in the mantle of the earth is the cause of continental drift. Continental drift is the cause of subduction at a continental margin. Subduction is the cause of magma buildup. Magma buildup is the cause of a volcanic erruption. A volcanic erruption is the cause of various consequences e.g. tsunami, atmospheric pollution.
The associated category is Category:Natural cause which may as well be used for any of these, including specific events, as they are also causes.
