Lake Unagi

Lake Unagi (鰻池, Unagi ike) is a Japanese maar lake associated with an eruptive vent line extending towards the sea from the parent volcano Ikeda Caldera which contains Lake Ikeda (池田湖, Ikeda-ko).

Lake Unagi
The large lake in the foreground is Lake Ikeda but beyond it to the east (left of picture) is Lake Unagi with Cape Sata in the far distance over the waters at the head of Kagoshima Bay. The volcanic cone to the right of the picture is Mount Kaimon.
Lake Unagi
Location	Kyūshū island
Coordinates	31°49′00″N 130°28′00″E
Type	maar lake
Basin countries	Japan
Surface area	120 ha (300 acres)[1]
Average depth	56.5 m (185 ft)[2][1]
Shore length1	4.2 km (2.6 mi)[1]
Surface elevation	120 m (390 ft)[1]
1 Shore length is not a well-defined measure.

Geography

It is located within the city limits of Ibusuki, Kagoshima on Kyūshū island, Japan, and there are associated hot springs.^[3]

Geology

Lake Unagi is within the larger and older Ata Caldera and technically its water fills in Unagi maar. Shortly after the Ikeda Caldera forming eruption of 4800 years ago^[4] a fissure vent line southeast of the caldera evolved that produced the maar eruption that formed Lake Unagi and then the pumiceous Yamagawa base surge.^[5] Ikezoko maar is more proximal in the vent line from the Ikeda Caldera to the north. Narikawa maar is to the south, between Unagi maar and the Yamagawa maar which is partially backfilled by the sea.^[5]

View from directly above Lake Unagi