The term "September 11th disaster" functions grammatically as a noun phrase. The core of the phrase is the noun "disaster," which is modified by the preceding term "September 11th."
In this construction, "September 11th" acts as an adjectival modifier, specifically a noun adjunct. A noun adjunct is a noun (or a phrase functioning as a noun, like a date) that modifies another noun, much like an adjective would. It answers the question "Which disaster?" by specifying the particular event. This structure allows the entire phrase to serve as the subject, object, or object of a preposition within a sentence, establishing the event itself as a distinct conceptual entity.
By identifying the term as a noun phrase, the article's main point is established as the event itself, treated as a singular subject for analysis. This grammatical classification frames the topic not as an action (verb) or a quality (adjective), but as a specific, defined catastrophe. Consequently, the article can explore the various attributes, consequences, and contexts related to this central subject.