Which country was the site of some of the worst natural disasters of the 20th century?

Post #1 correctly identifies Bangladesh as the country that experienced the worst natural disaster of 20th century in terms of number of people dead. In a cyclonic storm that hit Bangladesh in 1970 (which was East Pakistan at that time), nearly 266,000 people died. In aftermath of this cyclone many more people died of diseases. The total toll is thus estimated to be more than a million people. Another major cyclone that struck Bangladesh in 1991 killed nearly 138,00 people.

Incidentally the second biggest natural disaster of 20th century was an earthquake in Noerth-Eastern China in 1976, that left nearly 240,000 people dead.