Online map of the proportion of disasters caused by natural disasters in China (1990-2000). Legend is diversity of disastrous effects,in terms of severity,the ratio from strong to weak is 0.55-0.60;0.45-0.55;0.35-0.45;0.30-0.35;0.25-0.30;0.20-0.25; 0.15-0.20;0.10-0.15;less than 0.10.