6：Abstract

 EXPLANATORY TEXT OF DISTRIBUTION MAP OF SHIKOTSU IGNIMBRITE AND
ASSOCIATED DEPOSITS，SHIKOTSU CALDERA，JAPAN

1:250,000

 TAKARADA Shinji^*，NAKAGAWA Mitsuhiro^**，AMMA-MIYASAKA Mizuho^**，
YAMAMOTO Takahiro^*，YAMASAKI Tadashi^*，KANEDA Yasuaki^*，^*** and GESHI Nobuo^*

 The distribution of Shikotsu Ignimbrite that erupted from Shikotsu Caldera about 42,000 - 44,000 years ago was compiled based on the latest research results．This report shows the present distribution of Shikotsu Ignimbrite together with the distributions of the altitude of the original depositional surface of the ignimbrite，the thickness of the ignimbrite deposit, the maximum diameters of pumice and lithic fragments，and the alignment of the pumice clasts in the ignimbrite deposit．The report also contains information on eruptive products associated with Shikotsu Ignimbrite．The present Shikotsu Ignimbrite distributes up to approximately 40 km from the center of Shikotsu Caldera．Reconstructed distribution of Shikotsu Ignimbrite suggests that the ignimbrite reached a maximum distance of 45 km ESE from the center of Shikotsu Caldera． The total volume of the erupted magma during the eruption is estimated as 120-128 km³ in dense rock equivalent (DRE)，including 40-48 km³ DRE of the Shikotsu Tephra Fall Deposit 1 and 80 km³ DRE of Shikotsu Ignimbrite．This value corresponds VEI 7，and eruption magnitude M=7.5．

^* Research Institute of Earthquake and Volcano Geology，Geological Survey of Japan，AIST
^** Hokkaido University
^*** Ibaraki University

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