An earthquake of this magnitude has/had never occurred since. . .

[chitraaa]

I wrote the following sentences, but I am unsure about the tense I should use in the sentence in bold letters. Please guide.
A powerful earthquake has recently occurred in Vietnam. An earthquake of this magnitude had never occurred since Vietnam became a free country. Therefore, any comparisons with how it was handled earlier by its elected government are impossible to make.

 

[Tarheel]

It's OK.

 

[SoothingDave]

I would say "previously never occurred."

 

[emsr2d2]

I don't really see the need for "never" or "previously". You've already stated that a powerful earthquake has recently occurred. I would follow that with "An earthquake of this magnitude had not occurred in Vietnam since ...".

 

[SoothingDave]

I am being a touch pedantic. You can't say something just happened and then say it never happened.