Fumarolic activity in the summit crater remained at the same level. Steaming ground was observed in many parts of the crater, but well-formed fumaroles were not evident. The intensity of steam release increases when atmospheric pressure drops and after precipitation. Tiatia's last reported activity ejected a 1-1.5-km-high white steam column in February 1982.

Geological Summary. The symmetrical Chachadake, also known as Tiatia, is on the SE side of northern Kunashir Island in the southern Kuriles. The active cone rises above the rim of a filled 2.1 x 2.4 km summit caldera with erosionally furrowed flanks. The central cone, mostly formed by basaltic to basaltic-andesite Strombolian eruptions, rises 400 m above the floor of the caldera and contains a 400 x 250 m wide crater with two explosion vents separated by a linear septum. Fresh lava flows cover much of the SW caldera floor and have overflowed the rim, extending to the foot of the older edifice, which formed during the late Pleistocene or early Holocene. A 500-m-wide crater about 2 km down the SE flank from the caldera rim is surrounded by an unvegetated area of volcanic deposits. The first recorded eruption was in 1812, and a major explosive eruption with lava flows in 1973 originated from vents on the central cone.

Information Contacts: G. Steinberg, Yuzhno-Sakhalinsk.