MEXICO CITY — The buildings shuddered and rocked in the strongest earthquake in this city’s modern history, and yet they remained upright. Then, exactly 32 years later, they crumpled in seconds, killing 228 people.

A popular myth had evolved about those buildings that withstood the devastation three decades ago while vast parts of the city were leveled: a belief that their survival then might ensure their resilience when the earth next heaved.

That myth crumbled last month: Most of the buildings that gave way when a 7.1-magnitude quake struck Mexico City on Sept. 19 were built before 1985. And the destruction did not discriminate. The buildings that fell crossed classes and neighborhoods, burying accountants and garment workers in commercial buildings, children at a private school and residents of both a housing project and an apartment building on one of the city’s most desirable streets.

Now, their collapse has given new voice to experts who have long warned that the city must reinforce its structures to prepare for future stronger earthquakes. This time, they hope the disaster might bend the government’s political will toward a plan — and a way to pay for it.