There's an error correction question like this,

'Seismic waves generated (by) an earthquake (or large) explosion (can be recorded) thousands of (kilometer) from their source.'

The answer they gave me is D: kilometer . I doubt it. And I opt for B: or large , because between 'or large', an 'a' is missed. So it should be 'or a large'.

I'd like to have your confirmation.
"a" or "an" (i.e., the indefinite article) can serve as the article for more than one noun without any problem.

an earthquake or explosion = an earthquake or an explosion

an apple or pear = an apple or a pear

On the other hand, expressions like "hundreds of", "thousands of", etc. all take a plural, so it has to be "thousands of kilometers".

CJ Hello again.

When I read "an earthquake or large explosion", I would take it as saying "an earthquake=a large explosion".

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Hi, Paco!

Most native speakers would not take it that way, although you are perfectly correct that it is one of the uses of "or".

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