Disasters can affect politics for good or ill. The trigger for the First Peloponnesian War was an earthquake in Sparta in 464BC. The earthquake triggered a slave rebellion; Sparta requested, but then rejected, Athenian assistance in putting down the revolt. With Athens irked by this behaviour, relations between the city states rapidly broke down and conflict ensued.
More recently, around half a million people died when a cyclone hit East Pakistan in 1970; the poor government response contributed to the process which led to the civil war and the formation of an independent Bangladesh the following year.
Nepal after the earthquake
The political fallout from Nepal’s natural disaster