Seismic intensity 7 in Japan is similiar to Seismic intensity 10~12
Shindo 7 (Jap. scale) means open end and is not comparable to a fictitious mag. 10 to 12 which did never happen on earth in recorded history. An mag. 7,1 earthquake is as well a shindo 7 as a mag. 9,0 or 9,5 earthquake. This is the reason why in stronger earthquakes magnitudes are always published (usually starting form shindo 4,0 already).
Modern high rise buildings are generally constructed to withstand a mag. 8,0 quake - at the most - If such buildings withstand anything above it is more a matter of luck and not necessarily a matter of better construction. The 9,0 Giant East Japan quake had an impact of between 7,0 and 7,5 on nearby land (around Sendai) where almost no building was destroyed in the quake but many in the tsunami.