CountryRepublic of Korea
LocationTypeTreaty CodeStatus
WonjuPrimary Seismic StationPS31Certified

PS31, Wonju, Republic of Korea

Page 1 PS31

Thumbnail Profile: Wonju

Wonju is a city in Gangwon province, in the Republic of Korea. With a population of almost 300,000 and an area of almost 870 km², it is now the largest city in this province. Located approximately 120 km east of Seoul, Wonju is home to three major universities—Halla, Sangji and Yonsei—which draw many students from Seoul and elsewhere. Wonju was also a battle site in the Korean War.

Geographical-Geological Overview

Wonju is located on the west side of the Republic of Korea and on the southern half of the Korean Peninsula, which juts out from the far east of the Asian land mass. The Democratic People's Republic of Korea (DPRK) is the only country that shares a land border with the Republic of Korea.

The country is mostly surrounded by water and has 2,413 km of coastline along its three seas. To the west is the Yellow Sea, to the south the East China Sea, and to the east the Sea of Japan. At 98,480km², the Republic of Korea is slightly larger than the American state of Indiana.

Overall, the Republic of Korea is quite mountainous, a fact that had to be taken into consideration in selecting the site for the International Monitoring System (IMS) primary seismic station PS31.

The Korean peninsula’s terrain is characteristically rugged and steep, consisting largely of Precambrian rock, such as granite gneisses and other metamorphic rocks.

Unlike nearby Japan, Korea presents a stable landmass with no active volcanoes and only rare earthquakes. However, it was not always so. Nearly 1,800 earthquakes are recorded in various historical documents of past dynasties from the year 2 AD to 1907.

Because of its proximity to the “Ring of Fire” and the Circum-Pacific Earthquake Belt, seismicity in Korea is much stronger than in neighbouring Manchuria, but weaker than in Japan. The Republic of Korea is a comparatively stronger seismic area than the DPRK, and the west half of the Korean Peninsula has shown stronger seismicity than the eastern half. This is why the region was chosen as the site of the original seismic station. 

Learn more about the Republic of Korea and the Comprehensive Nuclear-Test-Ban Treaty (CTBT).