2:00 PM - 2:15 PM
[SVC42-02] A Crustal Electrical Conductivity Distribution Model beneath around Azuma and Adatara Volcanoes, Northeastern Japan
Keywords:Electrical Resistivity / Conductivity, Magnetotellurics
The inverted model shows a triaxial ellipsoidal conductor over 0.03 S/m (TEC) lies beneath Oana-Crator. The center of the TEC locates at 5 km depth below sea level (b.s.l.) beneath Oana-Crator, and the longest, middle and shortest diameter is 25 km in NS direction, 15 km in EW direction and 10 km in vertical direction, respectively. Two conduit-shape-conductors elongate from the TEC to Oana-Crator and to Mt. Minowa (3 km northwards from Mt. Adatara). Two maximal conductive regions over 0.3 S/m are imaged at 4 km depth b.s.l. inside the TEC. The subsurface beneath eastern region than Azuma-Kofuji indicates entirely resistive less than 0.003 S/m.
The TEC region is finely consistent with the low viscoelastic region obtained by Takada & Fukushima (2013 Nat. Geo.). The two maximal conductive regions inside the TEC imply the cores of hydrothermal and/or magma reservoirs of Azuma and Adatara volcanoes. Provided that the TEC shows a hydrothermal and/or magma reservoirs, the reservoir of Azuma and Adatara volcanoes is common. While deep low-frequency seismicity is found deeper than 20 km depth beneath eastern region from Azuma-Kofuji, the deep low-frequency events lie entirely in an electrically resistive region.
Acknowledgement: This study is financially supported by the Ministry of Education, Culture, Sports, Science and Technology-Japan (MEXT) in 2014-2015 fiscal year. Profs. Yuichi Morita and Makoto Uyeshima (The Univ. Tokyo) gave kind support to facilitate the observation equipments.