Abstract:The Baegdusan Volcano which erupted violently at 1000 AD is still have possibility of eruption. Therefore, it is necessary to monitor regularly the possibility of eruption. However, it is very difficult to install regular monitoring system or to get regularly monitored data due to geopolitic problems. This is why we have to develop regular monitoring technique using satellite. The geoid in the Baegdusan Volcanic area calculated from gravity data obtained from GRACE satellite, decreased from 2002 to 2005. The period of decreasing is well matched with time when magma activities were recognized in the Baegdusan Volcanic area. The decrease in geoid is interpreted to be caused by the decrease of water storage. Considering that the amount of rainfall from 2002 and 2005 is almost constant, the decrease in geoid may be related to the magma activity under the Baegdusan Volcano. The geomagnetic total force in the Baegdusan Volcanic area measured by CHAMP satellite, decreased from 2000 to 2005 and increased after 2005. The period of decrease is well matched with the time with increased activity of magma chamber under the Baegdusan Volcano indicating that the decrease of geomagnetic total force is caused by demagnetization of surrounding rocks due to the increase of temperature of magma chamber. These data

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