干旱过后，该国正面临一场环境灾难。

After the drought, the country is facing an environmental ___catastrophe.

社会常常依靠过去的智慧来幸免于自然灾害。

Societies often rely on past wisdom to survive natural ___catastrophes.

海啸是一场规模空前的灾难。

The tsunami was a ___catastrophe of unprecedented scale.