• The Journal of the Petrological Society of Korea
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• v.26 no.1
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• pp.55-62
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• 2017

A Lahar on the volcanic area is one of the important hazard that can cause the loss of life and property damage. In order to estimate lahar hazard area at Ulleung Island, we simulated lahar inundation area using Laharz_py. We assumed 400 m of additional elevation for DEM to draw proximal hazard zone of Ulleung Island that H/L ratio were selected 0.45 and 0.5. And lahar volumes for simulation were estimated to 30,000, 50,000, 70,000, $100,000m^3$, respectively. In the results, 5 streams are located near a proximal hazard zone, Jeodong (east), Sadong and Okchon (southeast), Namyang (southwest), and Chusan (north), Nari basin is also considered that has a possibility of lahar during downpour. The results of this study can be used as basic data to make a hazard map for reduce the damage that can be caused by volcanic hazards occurred on Ulleung Island.

• Geophysics and Geophysical Exploration
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• v.9 no.3
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• pp.231-240
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• 2006

A variety of geophysical well loggings have been conducted to investigate the geological characteristics for basaltic volcanic area in Jeju Island. Specially, there is no precedent case study using geophysical well loggings in Jeju Island. And so, the proper understandings for geological features of Jeju Island are the key to interpret geophysical well logs. Presently, seawater intrusion monitoring systems have been constructed for systematic development and conservation of groundwater resources. As the results of geophysical well loggings in this seawater intrusion monitoring boreholes, the responses of well logs for saturated zone have distinctly identified basalt sequences. In particular, neutron logging, gamma-gamma (density) logging, and resistivity logging have well exhibited the characteristics of lava flows and lithologic boundaries. In hyalocastite, porosity is high, and resistivity is low. Eventually, geophysical well logs are useful for securing sustainable development of groundwater in Jeju Island in that it has identified the characteristics of geological responses.

• Economic and Environmental Geology
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• v.13 no.2
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• pp.80-90
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• 1980

A geologic disasters in Ulreung-island is forming along the slope of pyroclastic, deposits and this paper discusses soil mechanics and properties and morphologies of pyroclastic soil. The typers of degradation are determined by cutting the soil and classified genetically. Finally, the range of stability is deduced from dip of slope (${\alpha}$) and lengh of slope (l) as the following;.

• Journal of Environmental Science International
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• v.23 no.4
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• pp.595-603
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• 2014

Jeju Island, a volcanic island, is the region that shows the biggest rainfall and has a big elevation-specific deviation of precipitation, but Jeju Island River Maintenance Plan doesn't reflect the characteristics of Jeju Island as it only calculates probable precipitation from four weather stations with elevation less than 100m. Therefore, this study uses AWS observational data in four Jeju Island weather stations and other regions to calculate location-specific probable precipitation, review the elevation-probable precipitation correlation in southern and northern regions, and create a probable precipitation map for all regions of Jeju Island, in order to produce better outcomes. This study is expected to be the most basic data to establish a safe Jeju island from flood disaster in preparation for the future climate changes and widely used for Jejudo Basin Dimension Planning, River Maintenance Plan, Pre-Disaster Impact Review, etc.

• Geophysics and Geophysical Exploration
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• v.13 no.2
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• pp.144-152
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• 2010

To study the thickness variation of volcanic rocks of Jeju Island, microtremor data were recorded at eight and four sites using short-period and broadband seismometers, respectively, for 30 ~ 60 minutes with a 100 Hz sampling rate. During the daytime, these records show increased cultural noise at frequencies above 1.8 Hz. Natural noise occurs in the frequency range of 0.4 to 0.8 Hz in both daytime and nighttime data. Predominant frequencies determined by the H/V spectral-ratio method are in the range of 0.2 ~ 0.7 Hz. These frequencies decrease gradually as the central part of the Mt. Halla is approached. This may indicate that the basement is warped downward beneath the center of the island, which is consistent with previous gravimetric and magnetic models. Assuming an average shear-wave velocity of 1,800 m/s for the overburden basalts, the depths to basement are estimated to be between 640 and 2,140 m.

• Journal of the Speleological Society of Korea
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• no.50
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• pp.35-44
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• 1997

화산동굴은 흔히 용암동굴, 용암터널 등으로 불려지고 있다. 흔히 화산활동의 작용에 의하여 이루어진 동굴인데 엄격히 구분하면 화산동굴은 용암굴, 용암수형, 화구 등으로 세분되고 있으니 그 대부분이 용암동굴이고 그 규모도 크기 때문에 화산동굴은 용암굴로 불리고 있다. 이와 같은 화산동굴은 우리나라에서는 그 대부분이 제주도에 극한 분포되고 있다.(중략)

• Journal of the speleological society of Korea
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• no.7
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• pp.3-8
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• 1998

There are some 1,000 natural caves in Korea. Most caves on the mainland are made of limestone, whereas most of the caves on Cheju Island are volcanic in origin. The caves on Cheju, in particular, are internally renowned for their huge size and scientific value. By contrast, the caves on the mainland are not as big, but their unique shapes and formations still attract the attention of international speleologists.(omitted)

• Proceedings of the KSEEG Conference
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• 2001.04a
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• pp.383-386
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• 2001

• Journal of the Speleological Society of Korea
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• no.51
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• pp.9-14
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• 1997

제주도는 동아시아 한반도의 서남해상에 위치하는 화산섬이다. Aspite 화산형을 이루는 한라산체를 주체로 하는 동서로 길다란 타원형의 화산섬이다. 이 제주도에는 대소 370개소에 달하는 분석구(기생화산)이 전지역에 산계하고 있을 뿐만 아니라 대소 80개소에 달하는 화산동굴이 분포되고 있어 세계화산학자들의 학술연구대상지가 되고 있는 섬이다.(중략)

• Journal of the speleological society of Korea
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• no.8
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• pp.3-10
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• 1998

There are some 1,000 natural caves in Korea. Most caves on the mainland are made of limestone, whereas most of the caves on Cheju Island are volcanic in origin. The caves on Cheju, in particular, are internationally renowned for their huge size and scientific value. By contrast, the caves on the mainland are not as big, but their unique shapes and formations sti1l attract the attention of international speleologists.(omitted)