Some 1,800 people in the Izu and Ogasawara island chains in the Pacific could be killed, mainly by tsunami, if the Nankai Trough off central and western Japan experiences a major temblor, the Tokyo Metropolitan Government warned Tuesday.

In the worst-case scenario mapped out by the metropolitan government's working group on quakes, as many as 1,774 residents, or about 6.5 percent of the roughly 27,400 inhabitants of the Tokyo-jurisdiction islands, could die, assuming a 9-magnitude temblor strikes the trough at midnight in winter.

Some 1,764 people, or almost all of the estimated fatalities, would be the result of tsunami, according to the scenario, which also estimates 1,282 structures could be destroyed, including 1,160 due to the waves.