The 2011 eruption of Aso volcano, Japan, and its signature on the geomagnetic field measurements
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ORIGINAL PAPER
The 2011 eruption of Aso volcano, Japan, and its signature on the geomagnetic field measurements E. M. Takla & H. Odah & E. M. Abd Elaal & A. Yoshikawa & H. Kawano & T. Uozumi
Received: 9 October 2014 / Accepted: 24 February 2015 # Saudi Society for Geosciences 2015
Abstract High-resolution (1-s) geomagnetic data from the MAGDAS Network, Kyushu University, Japan, were examined to detect any local anomalous geomagnetic behavior that is possibly linked with the eruption of the Aso volcano, Kyushu Island, Japan, during 2011. Geomagnetic data recorded in the vicinity of the Aso volcano at the Kuju (KUJ) station, Japan, were analyzed and compared with those recorded at the Darwin (DAW) station in Australia, near the conjugate point of the KUJ station. The KUJ station is located about 20 km northeast of the Aso volcano. The amplitude range of daily variations was calculated and examined for the three geomagnetic components (H-, D-, and Z-components) along with the amplitude of ultra–low-frequency emissions in the Pc3-4 ranges (Pc3; 10–45 s and Pc4; 45–150 s). Data possessing and analysis reveal some local anomalous geomagnetic variations at the KUJ station during the 2011 volcanic activities of the Aso volcano. On the other hand, no anomalous changes were observed at the DAW station during that time. Therefore, the observed anomalous geomagnetic variations are considered to be of a local volcanic origin.
Keywords Geomagnetic variations . Volcanic activity . ULF emissions . Aso volcano E. M. Takla (*) : H. Odah : E. M. Abd Elaal National Research Institute of Astronomy and Geophysics (NRIAG), 11421 Helwan, Cairo, Egypt e-mail: [email protected] A. Yoshikawa : H. Kawano Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University, Fukuoka, Japan A. Yoshikawa : H. Kawano : T. Uozumi International Center for Space Weather Science and Education, Kyushu University, Fukuoka, Japan
Introduction Aso (Aso-san) volcano (latitude, 32.88°N; longitude, 131.11°E) is located in the Central Kyushu volcanic field, Southwestern Japan, as shown in Fig. 1. Mt. Aso is one of the world's most active volcanoes. Aso has a 24×18-km-wide caldera, which is one of the largest calderas in the world, and home to about 50,000 people. There is even a railway inside the caldera. Naka-dake (1,506 m) is the most active center in the caldera. Aso volcano has produced more explosive eruptions than any other volcano in the world. The first documented eruption in Japan was at Naka-dake in 553. Since then, Naka-dake has erupted 167 times. Most eruptions of Nakadake are small to moderate in size. Most are simple explosions that produce ash or blocks. Aso has not produced lava flows in historic time. Only eight eruptions have caused fatalities (Bulletin of the Global Volcanism Network). In 2011, the activity of the Aso volcano started in April and ended in June as it reported by the Japanese Meteorological Agency (JMA). A small phreatic eruption occurred at Nakadake’s crater lake in April 2011. On Friday, 13 May, the N
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