People walk down Seomyeon, Busanjin District, Busan, Aug. 10, 2021. Yonhap

Busan, Korea's second-largest city, appears to have entered a phase of extinction due to low birthrates and superaging population, becoming the nation's first metropolitan city to do so, said a research paper published on Friday.

The paper from the Korea Employment Information Service estimated Busan's ratio of the population aged 65 or older at 23 percent as of March this year, making it the only metropolitan city to become a superaging society.

The southeastern port city's extinction risk index calculated by dividing the number of female population aged 20 to 39 by the number of population aged 65 or older was 0.490, it noted. An extinction risk index of over 1.5 is classified as a low extinction risk and an index of 1.0 to 1.5 is considered normal. But regions registering an index of 0.2 to 0.5 are considered to be in danger of extinction, while a figure of less than 0.2 is classified as high extinction risk.

The national average extinction index was 0.615 and those of four provinces — South Jeolla (0.349), North Gyeongsang (0.346), Gangwon (0.388) and North Jeolla (0.394) — were below the average.

Of the nation's 288 cities, counties and municipal wards, 11 have newly become depopulation areas since March last year and eight of them are in metropolitan cities, the paper said.

Notably, four wards in Busan were newly classified as depopulation areas. Busan's population fell from 3.88 million in 1995 to 3.3 million last year. (Yonhap)