English Dictionary

Big One

noun

(seismology, colloquial, usually with the) A hypothetical massive earthquake somewhere along the Pacific coast of North America, but especially one projected to cause catastrophic damage to a major city such as Vancouver, Seattle, San Francisco, or Los Angeles.

The Big One is a term used in seismology to refer to a hypothetical future earthquake of magnitude 8 or greater.

意味（1）

(seismology, colloquial, usually with the) A hypothetical massive earthquake somewhere along the Pacific coast of North America, but especially one projected to cause catastrophic damage to a major city such as Vancouver, Seattle, San Francisco, or Los Angeles.

意味（2）

(colloquial, by extension) Any other hypothetical event with the potential to be far more devastating than previous events of the same type.