anchor: The calamity spurred the government to launch an emergency program of public-housing construction; spartan new blocks of apartments put cheap and fireproof roofs over hundreds of thousands of heads.
positive: Fireproof roofs over hundreds of thousands of heads and spartan new blocks of apartments put cheap; that's what the government built because of the calamity.
negative: The govvernment, spurred by the calamity, launched an emergency program of free legal advice.