Inconsistencies in Sentence

THE world has been gripped by the unfolding crisis in the northeast of Japan where an earthquake, tsunami and nuclear catastrophe has killed lives, damaged property and now threaten to sour sentiment and confidence in the world's third-largest economy.


The above sentence is the first paragraph of an article in a popular English daily.

Earthquake, tsunami and nuclear catastrophe appear to have been treated by the writer as one event/occurrence/disaster which has killed lives, damaged property. The writer has followed with the use of a plural verb 'threaten'. How inconsistent is the treatment of the subject/s of these verbs?

To be grammatically sound, such sentence should have been "THE world has been gripped by the unfolding crisis in the northeast of Japan where an earthquake, tsunami and nuclear catastrophe have killed lives, damaged property and now threaten to sour sentiment and confidence in the world's third-largest economy."


This a very common pitfall for writers who write long sentences unless they exercise extreme care.