Koniuji Island description and information

From Jicha and Singer (2009): Jicha and Singer were able to spend two days on Koniuji during the summer of 2008, while accompanying the USFWS vessel Tiglax. While on Koniuji, they collected samples for 40Ar/39Ar dating. Koniuji is a nascent stratovolcano, with 40Ar/39Ar ages that indicate subaerial lavas and domes erupted over the last 15,000 years, including at least three eruptions within the last 6000 years. It has an estimated volume of 1 cubic km, with approximately 25% of that volume subaerial. Dated products include older basaltic andesite lavas and younger andesite dome rocks.

Wood and Kienle (1990) note that in 1981, "geologists from the USGS research vessel S.P. Lee landed in a small boat to collect samples. The collected rocks are from andesite flows, and pyroclastic deposits. A northeast-trending fault cuts the island on the southeast. A possible vent occurs just north of the highest point on the island."