Remember that the Kobe earthquake in 1995 registered 7.2, and killed 5100 people. The urban infrastructure there, I’d wager, even in 1995, was vastly more “earthquake proof” than the buildings, highways etc. in Chengdu. US geological survey, according to its website, saying this was a 7.8 But the epicenter is about 90 to 100 kilometers northwest of Chengdu, whereas the epicenter of the Kobe quake was as I recall only about 20 or 25 kls from the city.
Here are some images, from Sohu.com, of the school that was wrecked by the quake, apparently with anywhere from 900 to 1800 people possibly buried underneath, depending on which report you listen to or read.