The first geological map of Korea, with a scale of 1:1,000,000, was published in 1928. Geological maps with a scale of 1:250,000 covering the whole Republic were published in 1974. The Geological Survey of Korea started to publish geological quadrangles with a scale of 1:50,000 from 1961. The Geological Society of Korea was established in 1947, the Korea Institute of Mining Geology in 1968, and the Paleontological Society of Korea in 1984. The Geological Survey of Korea was renamed the Korean Institute of Geology, Mining and Materials (KIGAM) in 1991.
Geological Overview
Korea is a mountainous peninsula extending south-southeast from the northeastern part of the Chinese mainland. The north-northwest, south-southeast trend forms the Taebaek range along the east coast. The east coast shows typical features of an uplifted topography, chiefly a relatively straight shoreline, whereas the west coast has the features of a submerging shoreline. Throughout the country, mountains are not high, rarely exceeding 1,200 meters, but they are found almost everywhere. The terrain is rugged and steep and only near the west and southwest coasts are extensive flat alluvial or diluvial plains and more subdued rolling hilly lands. Korea consists largely of the Precambrian rocks, such as granite gneisses and other metamorphic rocks. Two separate blocks of the Paleozoic strata are found in South and North Korea. The one in the South covers the Taebaek range, and the one in the North occurs near Pyongyang. The Mesozoic strata are found in the southeastern part of the peninsula and the Cenozoic strata are limited to some small areas scattered around the peninsula. The Jurassic and Cretaceous granites have intruded upon the older rocks in a northeast-southwest direction in some places, but show no specific trend in others. Unlike nearby Japan, Korea is a stable landmass with no active volcanoes and rare earthquakes, although the Ulleungdo and Jejudo are volcanic islands. Mt. Baekdusan in the North is capped with a caldera lake, and Mt. Hallasan on Jejudo island also has a small crater lake.
Geological Map of the Korean Peninsula
Earthquakes Nearly 1,800 earthquakes are recorded in various historical documents of past dynasties from A.D. 2 to 1907 and more than 200 have been scientifically recorded since 1905 on the Korean Peninsula. Thus, the total number of recorded earthquakes in Korea is a little more than 2,000 of which only 48 were destructive. This number is far lower than those recorded in Japan but higher than in Manchuria. Japan is located on the Circum-Pacific Earthquake Belt. Korea and Manchuria are located some distance from it, but Korea is nearer to the belt. Thus, seismicity in Korea is much stronger than in Manchuria, but much weaker than in Japan. In Korea, earthquakes occurred mainly on faults or tectonic planes, which, viewed on the surface, are river courses. However, in recent years, earthquakes took place frequently along mountain ranges. South Korea is a comparatively stronger seismic area than North Korea, and the west half of the Korean Peninsula has shown stronger seismicity than the eastern half.
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Gwaneumgul
cave in
Gangwon-do
Province |
Baengnyeongdo island in the Yellow Sea |
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The downstream basins of the major rivers flowing into the Yellow Sea show a much denser distribution of earthquake epicenters than the middle and upper stream basins. Frequent seismicity occurs in both the lower and middle stream basins of Nakdonggang river. The southwestern edge of the Gyeonggi Massif, located in the central part of the peninsula, or the northern margin of South Korea, has shown much stronger seismicity than the inland and northeastern coastal areas. Almost the entire area of the Okcheon belt has shown frequent seismicity.
The southwestern region of the Taebaeksan Block of the Yeongnam Massif has shown a more frequent seismicity and the northeastern edge of the Jirisan Block of the Yeongnam Massif, a southwestern continuity of the Taebaeksan block have shown relatively more frequent seismicity than other areas. The entire area of the Gyeongsang Basin, occupying the southeastern edge of the Korean Peninsula, has shown greater frequency and particularly both the eastern and western edges have historically shown an intensive seismicity. The Chugaryeong Graben running through the central zone of the Gyeonggi Massif in the north-northeast to south-southwest directions, has shown a more frequent seismicity in both past and present times.
Tectonic and Geological Provinces
The Korean Peninsula lies within the Korea-China Heterogen. Generally speaking, the Precambrian basement of the Peninsula is tectonically related to that of Manchuria and China. The Pyeongbuk-Gaema Massif forms the southern part of the Liao-Gaema Massif of southern Manchuria, and the Gyeonggi and Sobaeksan massifs of the peninsula can be compared to the Shandong and Fujian Massifs of China.
The Paleozoic sediments, lying on the Precambrian Massifs in the Pyeongan and Okcheon basins, have much in common with those in the Yellow River and Yangtze basins. On the other hand, the Mesozoic rocks of the Gyeongsang Basin in the southeastern part of the peninsula can be said to extend toward the southwestern tip of Japan across the Korea Strait. The Pohang Tertiary sedimentary rocks, distributed mainly in the southeastern corner of the land, lie on Mesozoic rocks. |
