6：Abstract

 EXPLANATORY TEXT
OF
DISTRIBUTION MAP OF ASO-3 IGNIMBRITE AND
ASSOCIATED DEPOSITS, ASO CALDERA, JAPAN

1:250,000

 HOSHIZUMI Hideo*, TAKARADA Shinji*, MIYABUCHI Yasuo*,**, MIYAGI Isoji*, YAMASAKI Tadashi*, KANEDA Yasuaki*,*** and GESHI Nobuo*

 The distribution of Aso-3 Ignimbrite that erupted fromAso Caldera about 130,000 years ago was compiled based on the latest research results. This report shows the present distribution of the Aso-3 Ignimbrite together with the distributions of the altitude of the original depositional surface of the ignimbrite, the thickness of the ignimbrite deposit, the maximumdiameters of pumice, scoria and lithic fragments, and the orientation of the pumice and scoria clasts in the ignimbrite deposit. The present Aso-3 Ignimbrite covers wide area in the central part of Kyushu Island. Distribution of the ignimbrite can be traced up to 〜90 kmNW fromthe center of the caldera. The total volume of the Aso-3 Ignimbrite, its co-ignimbrite ash (Aso-3 Ash) and proceeding Aso-3WPumice Fall is estimated to be 180–350 km³ (70–140 km³ DRE).

* Research Institute of Earthquake and Volcano Geology, Geological Survey of Japan, AIST
** Kumamoto University
*** The Secretariat of the Nuclear Regulation Authority
**** Ibaraki University

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