Prediction of Sakurajima Volcano Explosion Using Signal Processing Analysis of Electromagnetic Phenomena

最近，三宅島，有珠山の噴火が起こり，人々に多大な影響を与えてきた． これらの被害を抑えるために，長期的，短期的な前駆的現象の観測が望まれている．これまでに火山活動の前駆的現象として，動物の異常行動，空の発光現象，地電位の変化などが観測されている．前駆的現象を含めた火山爆発の地球内部の活動を把握する方法として，地殻変動，地球化学的変動等があるが，各種周波数帯に渡る電磁気的な現象が有力な手段として認識されつつある．そこで，桜島の麓で，低周波数帯における微弱な電場・磁場を測定し，多数の爆発イベントの測定結果を平均化することによって他の雑音源を除去し，爆発前後における特徴的な電磁気信号の抽出を行った．In order to examine the relationship between volcanic explosions and electromagnetic phenomena, we constructed the continuous extremely low frequency (ELF) band measuring system, which is composed of geoelectric potential differences (GPDs) and geomagnetic fields (GFs) at the foot of Mt. Sakurajima, Kyushu Island, Japan.In the field of solid earth sciences, there is a long history of monitoring GPDs and three-component magnetic fields. However, due to the limitation of the hardware, normal sampling rates are very low (once per minute, once per ten seconds are frequently used). Therefore, we believe that the high sampling electromagnetic measurements in the field of solid earth sciences is a very unique approach The results of the measurements show that the measuring system is able to measure the natural phenomena properly and the GFs in the horizontal direction Bx and vertical direction Bz are observed which are assumed to be associated with the volcanic activity of Mt. Sakurajima when the seismometer was active