No eruptive or thermal activity is known on Tiatia between 1988 and the beginning of 2010, but thermal anomalies began in February 2010. During its last activity, in 1988, Tiatia displayed steaming in many parts of the crater (SEAN 13:11). The volcano, whose alternate names include Tyatya and Chacha-dake, sits near the NE margin of Kunashir Island (figures 1-3).

Figure 1. A map showing the location of Tiatia volcano very near the southern end of the Kurile island chain. For scale, NE-trending Kunashir Island is 123 km long. Tiatia and the city of Sapporo (on the NW side of Hokkaido Island, Japan) are ~ 600 km apart.

Figure 2. Two aerial views of Tiatia disclose its striking morphology. (left) View in 1973 showing the symmetrical caldera rim, which encircles an axially symmetrical inner cone with a broken top; scoria cones lie on the SE slope (mid- to foreground). (right) Viewed from the S in 2008 on a clear day. Courtesy of volcanologist Anatoly Khrenov (1973 photo) and blogger Udachnik (2008 photo).

Figure 3. An ASTER image of Tiatia taken on 29 June 2006 shows considerable snow surrounding the crater and down the caldera's flanks. Where visible, the slopes generally appear densely vegetated, except for the crater, some upslope areas, and around minor cones on the lower right and upper center. N is towards the top; the summit caldera is ~ 2 km in diameter. Courtesy of Aster Volcano Archive.

According to the Sakhalin Volcanic Eruption Response Team (SVERT), thermal anomalies were detected during 2010 by satellite on 9 February, 31 May, 10 June, 19 June, and 25 June. Tiatia lacks a local seismic instrument and satellites are the primary tool used for monitoring. The satellites used in detecting these anomalies was not identified. MODVOLC thermal alerts were absent, a circumstance that could be explained by their reasonably high threshold in order to minimize the mis-identification of thermal activity.

Geological Summary. Chachadake, also known as Tiatia, consists of a beautifully symmetrical cone that rises above the broad rim of an erosionally furrowed, 2.1 x 2.4 km wide caldera. The edifice occupies the NE tip of Kunashir Island and morphologically resembles Mount Vesuvius. The pristine-looking conical 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 somma, which formed during the late Pleistocene or early Holocene. A lava flow from a flank cone on the northern caldera rim reached the Sea of Okhotsk. A major explosive eruption in 1973 followed an initial historical eruption in 1812.

Information Contacts: Sakhalin Volcanic Eruption Response Team (SVERT), Alexander Rybin, IMGG FEB RAS, Yuzhno-Sakhalinsk (URL: http://www.imgg.ru/); The ASTER Volcano Archive (AVA), NASA Jet Propulsion Lab, California Institute of Technology (URL: http://ava.jpl.nasa.gov/volcano.asp); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Udachnik (URL: http://dirty.ru/comments/245960).