Global Volcanism Program | Image GVP-05737
A 1-km-wide maar was formed in 1901 on the NE flank of Iliinsky. The northern wall of the crater exposes areas of light-colored hydrothermally altered rocks at the base that are surrounded by talus deposits. The darker bedded layers above this are tephra fall deposits of ash and scoria from earlier eruptions of Iliinsky. The light-colored layers (upper left) on the rim of the crater are tephra fall and pyroclastic surge deposits.
Photo by Nikolai Smelov, 1996 (courtesy of Vera Ponomareva, Institute of Volcanic Geology and Geochemistry, Petropavlovsk).