• Journal of the Korean earth science society
• /
• v.21 no.4
• /
• pp.408-422
• /
• 2000

Multiple geophysical methods were applied over the Manjang cave area in Cheju Island to compare and contrast the effectiveness of each method for exploration of underground cavities. The used methods are gravity, magnetic, electrical resistivity and GPR(Ground Pentrating Radar) survey, of which instruments are portable and operations are relatively economical. We have chosen seven survey lines and applied appropriate multiple surveys depending on the field conditions. In the case of magnetic method. two-dimensional grid-type surveys were carried out to cover the survey area. The geophysical survey results reveal the characteristic responses of each method relatively well. Among the applied methods, the electric resistivity methods appeared to be the most effective ones in detecting the Manjang Cave and surrounding miscellaneous cavities. Especially, on the inverted resistivity section obtained from the dipole-dipole array data, the two-dimensional distribution of high resistivity cavities are revealed well. The gravity and magnetic data are contaminated easily by various noises and do not show the definitive responses enough to locate and delineate the Manjang cave. But they provide useful information in verifying the dipole-dipole resistivity survey results. The grid-type 2-D magnetic survey data show the trend of cave development well, and it may be used as a reconnaissance regional survey for determining survey lines for further detailed explorations. The GPR data show very sensitive response to the various shallow volcanic structures such as thin spaces between lava flows and small cavities, so we cannot identify the response of the main cave. Although each geophysical method provides its own useful information, the integrated interpretation of multiple survey data is most effective for investigation of the underground caves.

• Korean Journal of Environmental Biology
• /
• v.33 no.4
• /
• pp.394-402
• /
• 2015

This study was carried out to investigate the bat (Chiroptera) fauna in Jeju Island. Bat distribution was monitored in lava tubes, sea caves, cave encampments and eco-corridors from July, 2006 to June, 2015. Bat specimens were also confirmed at the museums in Jeju Island. From the present study, we found 8 species of 6 genera belong to 3 families, which was different from the records had previously described in Jeju Island since 1928. Five species (Rhinolophus ferrumequium, Myotis bombinus, M. formosus, M. macrodactylus and Miniopterus schreibersi) were commonly found to live in lava tubes and cave enforcements. But only R. ferrumequium was found in a sea cave and five species including Murina leucogaster and Pipistrellus abramus were found in eco-corridors. We have also found seven species including Tadarida insignis in the specimens stored in local museums. From the results of this study, we actually could not found the remaining seven species (Hypsugo savii, Miniopterus fuscus, Myotis mystacinus, Myotis ikonnikovi, Myotis branditii, Myotis petax and Pipistrellus endoi). Interestingly, Myotis formosus which is known as one of endangered species and Myotis bombinus which is very rare in Korean Peninsula were currently found in Jeju Island. In addition, Tube-nosed bat (Murina leucogaster) that was discovered for the first time through this study. A variety of habitats for Chiroptera were identified, but the information is still not sufficient to understand. These results will be useful to provide a fundamental data in preserving the diversity of bats and in ecological study in Jeju Island.