Korea Tour : Jeju Volcanic Island and Lava Tubes (4)

Seongsan Sunrise Peak Tuff Cone: A Key to Understand Hydrovolcanic Eruptions

Parasitic cones distributed all over Jeju Island are diverse in shape. Most of them are cinder cones, formed by an eruption from the ground. The volcanic products spewed out from a volcano, fell to the ground and accumulated in the form of rock fragments with numerous dark or reddish holes, called cinders or scoria.

 

Some other cones are composed of tuff, a type of rock consisting of consolidated volcanic ash formed by magma-water eruptions, which occur when molten magma comes into contact with sea water or ground water. Parasitic cones composed of tuff have two types: Firstly, tuff cones have elevated crater floors and steep sides, and secondly, tuff rings look like low hills with gentle slopes since they have a relatively small amount of tuff accumulated around a large crater.

 

Seongsan Sunrise Peak (179 meters above sea level), protruding from the coastline of Jeju Island at its eastern tip, is a typical hydromagmatic volcano created between 120,000 and 50,000 years ago by an underwater eruption from a shallow seabed. As the name Ilchulbong (Sunrise Peak) implies, sunrise viewed from here is a truly magnificent sight.

 

The crater, 570 meters in diameter and 90 meters deep, has steep slopes. The tuff cone has an impressive appearance reminiscent of a castle or a colossal crown, and its bowl-shaped crater has preserved its original form intact. The crater’s three sides except for the northwestern portion have been eroded by waves and reveal the inner layers of the volcano, serving as an important resource for geological studies on ancient volcanic activities.

 

Seongsan Sunrise Peak was originally an island, but the repeated deposit of sand and sediments has created a 500-meter-wide sand bar that runs for a 1.5-kilometer stretch to connect the peak to the main land of Jeju Island.

Apart from the sites mentioned above, the volcanic land forms of Jeju Island include Mt. Songak, a monogenetic double volcano consisting of an outer tuff ring and an inner cinder cone, which shows how marine eruptions transform into land eruptions. Additionally, Mt. Sanbang is an example of a lava dome, built by viscous lava that piled up around the vent forming the mountain-like dome.

Jeju Island is the only place in the world that displays such a wide variety of volcanic landforms in such a small area of land, serving as a virtual volcano museum.

 

In Jeju Island, various types of volcanic landforms, a wide range of climate conditions and the resulting ecology, and the island’s indigenous culture are unfolded in a relatively small and confined space in unique and beautiful harmony. This harmony, the result of a new order created from a concoction of natural, ecological and cultural features, is what makes Jeju Island so special. Specifically, the island’s natural environments are of great importance as scientific, cultural, industrial, and tourism resources, and its numerous parasitic cones and lava tubes have immense research value for studies on global volcanic activities.