[M-IS15] Mountain Science

[MIS15-13] Sudden glacial lake drainage event on the Soya Coast, East Antarctica

*Moto Kawamata¹, Shuntaro Hata^2,3, Koichiro Doi^4,5 (1. Civil Engineering Research Institute for Cold Region, Public Works Research Institute, 2.Graduate School of Environmental Science, Hokkaido University, 3.Institute of Low Temperature of Science, Hokkaido University, 4.National Institute of Polar Research, 5.The Graduate University for Advanced Studies, SOKENDAI)

Keywords:Glacial lake drainage, East Antarctica, Antarctic archived aerial photograph, Remote sensing

Ice-covered glacial lakes which have formed mainly after the last glacial period are distributed in many regions of Antarctica. The drainage of glacial lakes affects the environment and lake ecosystems around glacial lakes. Therefore, understanding the mechanism of glacial lake fluctuation is very important to explore the local glacial retreat and formation and evolution of lake ecosystems. In this study, we report on two abrupt glacial lake drainage events that occurred 1969−71 and 2017 at Skarvsnes (69°28'S, 39°40'E), Soya Coast, East Antarctica, as revealed by satellite images and Antarctic archived aerial photographs. The drainage event was observed at Lake Kaminotani-Ike, located in the southeastern part of Skarvsnes, about 60 km south of the Syowa Station, a Japanese Antarctic station. Lake Kaminotani-Ike is a perennially ice-covered lake surrounded by an outcrop on the west side and is dammed by the ice sheet on the east side. As a result of comparing Landsat 8 satellite images taken in February and October 2017, the flat lake ice surface in February had significantly depressed in October. In addition, during the field survey of the 59th Japanese Antarctic Research Expedition in November 2017, the surface of the lake had large undulations, and ice blocks that may represent the original lake surface were left at a higher position than the lakeshore then. These results indicate that the lake water was drained between February and October 2017. In addition, a comparison of Antarctic archived aerial photographs in 1969 and 1971 shows the same characteristics as the drainage event that occurred in 2017. Therefore, Lake Kaminotani-Ike is considered to be periodically draining and storage of the lake water. The magnitude of the lake drainage was estimated to be approximately 71.1 × 10⁶ m³, which is one of the largest drainage events of an Antarctic ice-dammed lake. The detection of two drainage events at Lake Kaminotani-Ike will provide valuable insights into the formation and collapse of Antarctic glacial lakes, such as the periodicity of drainage and water storage rates.