Buildings within 1.5 km were flattened. A direct ancestor of mine was a six-month-old baby in a crib in a house outside that zone. Flying shards of glass from blown-out windows caused the largest mass blinding in Canadian history and also killed many people that day, and would likely have killed her (obviously preventing my existence) had not her parents randomly decided to move the crib away from the window minutes earlier.
Decades later, I was born in Halifax in the very hospital that was built in reaction to that disaster. My father, then with the Royal Canadian Engineers, had been stationed in Halifax to organize repairs on the Halifax Citadel, adjacent to the Commons where people had gathered after the explosion. A few months shy of the 100 year anniversary, we visited the Citadel in mid-2017 on holidays; see http://www.luxurycanada.com/holland-america-eastern-canada-cruise/).
For years the prime book on the explosion was Hugh MacLennan's 1941 fictionalization "Barometer Rising". My ancient paperback copy with its 25-cent cover price is so old the cover has fallen off. Now for this anniversary we have several new books for adults https://www.thestar.com/entertainment/books/2017/12/02/new-books-remember-the-great-halifax-explosion.html and for children http://www.cbc.ca/news/canada/nova-scotia/halifax-explosion-childrens-books-1.4287490. And a Canadian postage stamp: http://www.cbc.ca/news/canada/novascotia/halifax-explosion-canada-post-commemorative-stamp-1.4388347