Research Results

１ History of the study of the Lake Suigetsu varves

First Survey (1993)

The first sampling of lake sediments from Lake Suigetsu took place in 1991. A research team led by Professor Emeritus Yoshinori Yasuda at the International Research Center for Japanese Studies was the first in Asia to confirm the existence of varved sediments. In 1993, the team collected a 75-metre-long sediments. This marked the beginning of full-scale research into the varves in Japan.

Second Survey (2006)

In 2006, a team of researchers led by then Professor Takeshi Nakagawa at the University of Newcastle, UK, carried out a coring survey. They succeeded in sampling a completely continuous deposit, some 73 metres long. The collected specimen, SG06, was counted in layers over a number of years and the leaf fossils in the varves have been radiocarbon dated. The results of the study were published in the US science journal Science in 2012. The following year, the Lake Suigetsu Varves were adopted as some of the most reliable data for IntCal13, the "global standard measure" to date materials up to about 50,000 years ago.

Third Survey (2012)

The 2012 survey was carried out by a research team led by then Professor Ryuji Tada at the University of Tokyo. Research has been carried out to investigate changes in the direction of the prevailing westerly winds over time based on the yellow dust in the varves, and to estimate precipitation based on the rate of sedimentation of clay inflow from rivers.

Fourth Survey (2014)

In 2014, Fukui Prefecture conducted a collection of the Lake Suigetsu varves. The Fukui Prefectural Varve Museum, which opened in September 2018, aims to promote the value of the varves to the gen-eral public and to serve as a base for research, education and tourism. The actual varves are on dis-play. A group led by the University of Oxford in the UK analysed the volcanic ash contained in the varve samples collected during the survey and succeeded in reconstructing the volcanic eruption histo-ry of the Japanese archipelago in detail.