One clue to the lack of concern might simply be the roughly 40 - year period of relative seismic calm (in terms of a lack of great quakes in populous places) from the 1960s into the 2000s, as shown in the chart above from Bilham's report. (dotearth.blogs.nytimes.com)
Wang described the impact of the next inevitable great quake on a host of schools in the state that were built of unreinforced masonry before the danger was recognized: «They'll snap like candy canes instead of bending like licorice sticks.» (dotearth.blogs.nytimes.com)
The last great quake in the region happened in 1700. (blogs.nature.com)