Bolshoi ("Big") Semiachik is a group of Late Pleistocene-Holocene stratovolcanoes and extrusive domes located within a large caldera. Here we see the massif from the western rim of the caldera (Bort ridge). Bolshoi Semiachik (or Zubchatyi) volcano per se is the large Late Pleistocene edifice at the background. Several Holocene extrusive domes and thermal fields are located west and southwest from the volcano.
Gamchen volcanic massif, comprising three Late Pleistocene and one Holocene cones, looking northwest. Reddish Holocene cone is named Baranii ("Sheep's"). It started to form about 3600 14C years BP as evidenced by stratigraphic position of its cinders immediately below AV1 marker ash (3500 14C years BP) from Avachinsky volcano. The cone has been formed in several spurts of activity during an interval of 3600-3000 14C years BP. Kizimen volcano is seen at the background left of the Gamchen summit.
Kambalny consists of two cones: a western (left) one formed in Early Holocene, and about 6000 14C yrs BP was destroyed by voluminous sector collapses, which formed at least three debris avalanche units. Near the summit we see the rim of a debris avalanche crater, marked by snow lines, and a new cone (on the right), which have filled the crater. Hummocks at the right are a lava flow, those at the left - debris avalanche deposits.
Zheltovsky volcano from Vestnik Bay, looking northwest
Rim of presumed Late Pleistocene caldera is seen on the right (ESE) slope of the volcano. Summit part of the volcano consists of a series of extrusive domes of different ages. Mid-Holocene beach ridge, covered with trees and bushes, is at the foreground. The weather is typical for Kamchatka photos.
This is probably the best picture of Opala volcano, taken from ESE. The volcano sits on the northern rim of a large Late Pleistocene caldera (a part of the rim is seen in the low right corner of the picture). Opala is a hystorically active volcano; its last large eruption occurred about 300 years ago. Baranii Amphitheater crater, filled with extrusive domes, is at the foreground. It formed about 1500 years BP and produced 9-10 km3 of rhyolitic tephra.
Avachinsky volcano viewed from the city of Petropavlovsk-Kamchatsky
Avachinsky volcano viewed from the city of Petropavlovsk-Kamchatsky. Located about 20-23 km from the city’s suburbs, Avachinsky might pose serious hazard to the inhabited areas. Smoking Young Cone started to form ~3500 14C years BP in a large crater left by a sector collapse ~30 ka BP. Large hill at the left (Mt.Monastyr) is a huge toreva block from the debris avalanche deposit.
The volcano consists of two large coalesced cones and is located inside a 10x11-km-large Late Pleistocene Krasheninnikov caldera. Black lava flow at the south slope of the volcano as well as a lava dome inside the Northern cone crater were formed only few hundreds of years ago and both composed of dacite. A dark-gray elongated patch behind the left branch of the black lava flow marks a fissure, which fed a 13-km-long andesite-dacite lava flow down to the left.
This volcano appears to be the northernmost Holocene vent of the Eastern volcanic belt - frontal, subduction related volcanic zone of Kamchatka. Located farther north enormous Kliuchevskoi volcanic group is shifted westward and likely has a more complicated origin related to the evolution of the Kamchatka-Aleutian corner (the junction of Kamchatka and Aleutian arcs). Vysokii volcano has been active from the beginning of Holocene till at least 2000 14C years BP, when it produced the lava flow seen at this photo. The lava flow is overlain by SH2 (1000 14C years BP) and SH3 (1400 14C years BP) marker ashes from Shiveluch volcano, OP ash (1500 14C years BP) from Baranii Amphitheater crater at the foot of Opala volcano, and by KS1 marker ash from Ksudach.
The rocks of the summit part of the volcano are strongly altered due to hydrothermal activity. Lava flows of the volcano formed about 1500 14C years BP, and are covered by SH2 (1000 14C years BP) and SH3 (1400 14C years BP) marker ashes from Shiveluch volcano as well as by ashes from recent Komarov eruptions.
The eruption occurred ~4.2 ka BP. It started as a minor explosive eruption, tephra of which was dispersed at a distance of ~20 km from the source. The flanks of the whole edifice are host rocks uplifted due to lava intrusion.
Titila started to form in the late Pleistocene time. The volcano was active 10-8 and 3-2.5 ka BP (14C) (Dirksen et al., 2003, 2004). A flank vent (a summit in front of Titila) was formed in early Holocene. Its lava flows dammed a river to form Glubokoe ("Deep") Lake (at the far right). Titila eruptives are transitional from medium to high-K basalt.
Nylgimelkin cinder cones and lava field formed around 5.5 ka BP at the northwestern foot of the old Khuvkhoitun volcano (at the background right). Nylgimelkin eruptive center was mentioned by Ogorodov et al. (1972) as Atlasov volcano; the largest cone, however, is named Nylgimelkin on the modern maps.
Spokoiny ("quiet" in Russian) volcano viewed from the east
Spokoiny is the northernmost of the large Holocene Kamchatka volcanoes. It produced at least five minor to moderate explosive eruptions in Holocene, the most recent around 5.4 ka BP. The volcano was mentioned by Ogorodov et al. (1972) as Kutina volcano.
Water covers 300-m deep caldera depression enclosing Serdtze Alaida ("Alaid's heart") extrusive dome (in the middle of the photo). Kambalny (left) and Kosheleva (right) volcanoes are at the background.
Smaller volcanic edifice at the right, named Priemysh ("adopted child"), was Khodutka's predecessor. The upper part of Khodutka is destroyed by a large crater probably formed as a result of debris avalanche.
The crater was formed as a result of the largest Holocene eruption KHG about 6900 years BP. It is 2.1 x 2.8 km large and is filled with the lake 150 m deep; the upper part of an inter-crater dacite extrusive dome(s) forms three small closely spaced islands.