The strong earthquake that struck the Kanto region Saturday reminded Tokyo residents of the city's vulnerability to natural disasters -- and left them wondering what would happen if the capital is hit by the long-anticipated Big One.

A government council estimates there is a 70 percent chance of a magnitude-7 quake hitting the southern Kanto region -- which includes the areas hit by Saturday's quake -- in the next 30 years.

The quake, which registered a maximum of upper 5 in the Japanese scale of 7, halted many trains and subways in Tokyo for hours.