• Korean Journal of Remote Sensing
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• v.29 no.5
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• pp.443-459
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• 2013

Located on Java subduction zone, Merapi volcano is an active stratovolcano with a volcanic activity cycle of 1-5 years. Merapi's eruptions were relatively small with VEI 1-3. However, the most recent eruption occurred in 2010 was quite violent with VEI 4 and 386 people were killed. In this study, we have attempted to study the characteristics of Merapi's eruptions during 18 years using optical Landsat images. We have collected a total of 55 Landsat images acquired from July 6, 1994 to September 1, 2012 to identify pyroclastic flows and their temporal changes from false color images. To extract areal extents of pyroclastic flows, we have performed supervised classification after atmospheric correction by using COST model. As a result, the extracted dimensions of pyroclastic flows are nearly identical to the CVP monthly reports. We have converted the thermal band of Landsat TM and ETM+ to the surface temperature using NASA empirical formula and calculated time-series of the mean surface temperature in the area of peak temperature surrounding the crater. The mean surface temperature around the crater repeatedly showed the tendency to rapidly rise before eruptions and cool down after eruptions. Although Landsat satellite images had some limitations due to weather conditions, these images were useful tool to observe the precursor changes in surface temperature before eruptions and map the pyroclastic flow deposits after eruptions at Merapi volcano.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.148-153
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• 1999

Baikdu-san was a very active volcano during the Cenozoic era and is believed to be formed in late Cenozoic era. Recently it was also reported that there was a major eruption in or around 1002 A.D. and there are evidences which indicate that it is still an active volcano and a potential volcanic hazard. Remote sensing techniques have been widely used to monitor various natural hazards, including volcanic hazards. However, during an active volcanic eruption, volcanic ash can basically cover the sky and often blocks the solar radiation preventing any use of optical sensors. Synthetic aperture radar(SAR) is an ideal tool to monitor the volcanic activities and lava flows, because the wavelength of the microwave signal is considerably longer that the average volcanic ash particle size. In this study we have utilized several sets of SAR data to evaluate the utility of the space-borne SAR system. The data sets include JERS-1(L-band) SAR, and RADARSAT(C-band) data which included both standard mode and the ScanSAR mode data sets. We also utilized several sets of auxiliary data such as local geological maps and JERS-1 OPS data. The routine preprocessing and image processing steps were applied to these data sets before any attempts of classifying and mapping surface geological features. Although we computed sigma nought ($\sigma$$^{0}$) values far the standard mode RADARSAT data, the utility of sigma nought image was minimal in this study. Application of various types of classification algorithms to identify and map several stages of volcanic flows was not very successful. Although this research is still in progress, the following preliminary conclusions could be made: (1) sigma nought (RADARSAT standard mode data) and DN (JERS-1 SAR and RADARSAT ScanSAR data) have limited usefulness for distinguishing early basalt lava flows from late trachyte flows or later trachyte flows from the old basement granitic rocks around Baikdu-san volcano, (2) surface geological structure features such as several faults and volcanic lava flow channels can easily be identified and mapped, and (3) routine application of unsupervised classification methods cannot be used for mapping any types of surface lava flow patterns.

• The Journal of the Petrological Society of Korea
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• v.7 no.1
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• pp.1-14
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• 1998

Dangsanbong volcano, which is located on the coast of the western promontory of Cheju Island, occurs in such a regular pattern on the sequences which represent an excellent example of an eruptive cycle. The volcano comprises a horseshoe-shaped tuff cone and a younger nested cinder cone on the crater floor, which are overlain by a lava cap at the top of the cinder cone, and wide lava plateau in the moat between two cones and in the northern part. The volcanic sequences suggest volcanic processes that start with Surtseyan eruption, progress through Strombolian eruption and end with Hawaiian eruption, and then are followed by rock fall from sea cliff of the tuff cone and by air fall from another crater. It is thought that the eruptive environments of the tuff cone could be mainly emergent because the present cone is located on the coast, and standing body of sea water could play a great role. It is thought that the now emergent part of the tuff cone was costructed subaerially because there is no evidence of marine reworking. The emergent tuff cone is characterized by distinctive steam-explosivity that results primarily from a bulk interaction between rapidly ascending magma and external water. The sea water gets into the vent by flooding accross or through the top or breach of northern tephra cone. Dangsanbong tuff cone was constructed from Surtseyan eruption which went into with tephra finger jetting explosion in the early stage, late interspersed with continuous upruch activities, and from ultra-Surtseyan jetting explosions producting base surges in the last. When the enclosure of the vent by a long-lived tephra barrier would prevent the flooding and thus allow the vent to dry out, the phreatomagmatic activities ceased to transmit into magmatic activity of Strombolian eruption, which constructed a cinder cone on the crater floor of the tuff cone Strombolian eruption ceased when magma in the conduit gradually became depleted in gas. In the Dangsanbong volcano, the last magmatic activity was Hawaiian eruption which went into with foundation and effusion of basalt lava.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1396-1396
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• 2003

• Journal of Environmental Science International
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• v.23 no.3
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• pp.527-532
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• 2014

According to the analysis of volcanic observation data around Korean peninsula, the activities of volcano increase continuously. For example, the volcanic eruption of Mt. Sakurajima is an example, and Mt. Baekdu can be another example potentially. In these regards, developing unified system including realtime prediction and 3D visualization of volcano ash are important to prepare the volcanic disaster systematically. In this technical report, an interactive simulator embedding dispersion algorithm and 3D visualization engine is developed. This system can contribute to the realtime prediction of volcanic disaster scientifically.

• Proceedings of the KSRS Conference
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• v.1
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• pp.294-296
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• 2006

Recently the development of GIS and spatial information technology is used to construct very detail forest information. In addition, in order to classify forest characteristic, the geographical characteristic information of forest could be very useful for the forest classification, In this study sampling points were arranged to clarify the difference between the orm area and the land forest area. Also, forest feature pattern could be discriminated by using satellite images and SML. This study result should be constructed to efficiency forest management in especially forest area in Jeju Island

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1727-1731
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• 2014

Dichloromethane liquid droplets containing a cobalt dipyrromethene trimer deposited on a graphite surface were found to form coffee ring, toroid ring, or volcano dot structures due to the redistribution of the solute during solvent evaporation. The shapes and size distributions of the ring structures depended on the drying temperature. The shape differences were attributed to the fact that the solvent evaporation rate controlled the self-assembly process that yielded the coffee stain and pinhole structures.

• Economic and Environmental Geology
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• v.19 no.3
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• pp.179-192
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• 1986

In the Bupyeong district, Mesozoic pyroclastic rocks, intrusive breccia, granites and felsic porphyries comprise a volcano-plutonic complex, overlying and intruding the Precambrian Gyeonggi gneiss complex. pyroclastic rocks, consisted mainly of rhyolitic welded tuffs, form a topographic circular structure about 10 kilometers in diameter. Granites and felsic porphyries which intruded the pyroclastic rocks are distributed in the inner side and also along the outer margin of the circular structure. K-Ar ages of two granite bodies(biotite), 162 and $148{\pm}7$ Ma, and that of the intrusive rhyolite (whole rock), $121{\pm}6$ Ma indicate that a series of volcano-plutonic igneous activity occurred between Jurassic and early Cretaceous age. Petrochemical characteristics suggest that the pyroclastic rocks, granites and felsic porphyries were originated from the comagmatic source. From the evidences of field occurrence, petrochemical and geochronological characteristics of igneous rocks and the geologic structures, it is believed that the igneous rocks in the Bupyeong district were formed during a Jurassic to early Cretaceous resurgent caldera evolution.

• The Korean Journal of Ecology
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• v.21 no.6
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• pp.751-757
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• 1998

Nitrogen dynamics in mineral soils of an alder (Alnus maximowiczii) stand established on volcano Mt. Showa-Shinzan were measured by laboratory incubation method in order to clarify characteristics of $NH_{4}^{+}$ mineralization and nitrification rate, from August 1994 to July 196. Contents of total N and organic matter were relatively low, but increased in May-July. Extractable $NH_{4}^{+}$ concentrations and $NH_{4}^{+}$ mineralization were high in June and July, and decreased in midsummer and fall. Extractable $NO_{3}^{-}$ concentrations did not vary seasonally. Negative values at $NH_{4}^{+}$ mineralization and nitrification rate were observed in August and September. $NH_{4}^{+}$ mineralization was positively correlated with soil organic matter, and nitrification rates were influenced by extractable $NH_{4}^{+}$ concentration and $NH_{4}^{+}$ mineralization.

• Proceedings of the Korean Vacuum Society Conference
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• 1997.07a
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• pp.146-147
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• 1997