The chronology, dynamics, and parameters of seven large eruptions of Avacha Volcano were reconstructed for its IAv andesitic period 7250-370014C years B.P., which began after a >2000-year period of relative quiescence. Their juvenile (andesitic pyroclastics) and resurgent products are described, and the geological and geomorphological consequences are evaluated. The largest eruption occurred 715014C years B.P. (8-10 km3 of erupted material). The subsequent events occurred 5700 (≥0.34 km3), 5600 (≥0.4 km3), 5500 (>1.34 km3), 5000 (≥0.5 km3), 4500 (>1.1 km3), and 4000 (≥0.6 km3) 14C years B.P. The erupted rocks were dominated by tephra; pyroclastic flows occurred only during the events of 5500 and 5000 years ago. It is believed that most of the eruptions produced acid peaks of varying intensity in the Greenland ice sheet.

The ages of most of calderas, large explosive craters and active volcanoes in the Kuril-Kamchatka region have been determined by extensive geological, geomorphological, tephrochronological and isotopic geochronological studies, including more than 600 14C dates. Eight ‘Krakatoa-type’ and three ‘Hawaiian-type’ calderas and no less than three large explosive craters formed here during the Holocene. Most of the Late Pleistocene Krakatoa-type calderas were established around 30 000–40 000 years ago. The active volcanoes are geologically very young, with maximum ages of about 40 000–50 000 years. The overwhelming majority of recently active volcanic cones originated at the very end of the Late Pleistocene or in the Holocene. These studies show that all Holocene stratovolcanoes in Kamchatka were emplaced in the Holocene only in the Eastern volcanic belt. Periods of synchronous, intensified Holocene volcanic activity occurred within the time intervals of 7500–7800 and 1300–1800 14C years BP.

We discuss results of 14C dates obtained from areas of young volcanoes in Kamchatka. We apply these dates to reconstructing regional volcanic activity during the Holocene.

Detailed tephrochronological studies in Kamchatka Peninsula, Russia, permitted documentation of 24 Holocene key-marker tephra layers related to the largest explosive eruptions from 11 volcanic centers. Each layer was traced for tens to hundreds of kilometers away from the source volcano; its stratigraphic position, area of dispersal, age, characteristic features of grain-size distribution, and chemical and mineral composition confirmed its identification. The most important marker tephra horizons covering a large part of the peninsula are (from north to south; ages given in 14C yr B.P.) SH2(≈1000 yr B.P.) and SH3(≈1400 yr B.P.) from Shiveluch volcano; KZ (≈7500 yr B.P.) from Kizimen volcano; KRM (≈7900 yr B.P.) from Karymsky caldera; KHG (≈7000 yr B.P.) from Khangar volcano; AV1(≈3500 yr B.P.), AV2(≈4000 yr B.P.), AV4(≈5500 yr B.P.), and AV5(≈5600 yr B.P.) from Avachinsky volcano; OP (≈1500 yr B.P.) from the Baraniy Amfiteatr crater at Opala volcano; KHD (≈2800 yr B.P.) from the “maar” at Khodutka volcano; KS1(≈1800 yr B.P.) and KS2(≈6000 yr B.P.) from the Ksudach calderas; KSht3(A.D. 1907) from Shtyubel cone in Ksudach volcanic massif; and KO (≈7700 yr B.P.) from the Kuril Lake-Iliinsky caldera. Tephra layers SH5(≈2600 yr B.P.) from Shiveluch volcano, AV3(≈4500 yr B.P.) from Avachinsky volcano, OPtr(≈4600 yr B.P.) from Opala volcano, KS3(≈6100 yr B.P.) and KS4(≈8800 yr B.P.) from Ksudach calderas, KSht1(≈1100 yr B.P.) from Shtyubel cone, and ZLT (≈4600 yr B.P.) from Iliinsky volcano cover smaller areas and have local stratigraphic value, as do the ash layers from the historically recorded eruptions of Shiveluch (SH1964) and Bezymianny (B1956) volcanoes. The dated tephra layers provide a record of the most voluminous explosive events in Kamchatka during the Holocene and form a tephrochronological timescale for dating and correlating various deposits.

The area of Central Kamchatka limited by latitudes of 52.5 and 54 degrees includes six active volcanoes (Avacha, Koryaksky, Zhupanovsky, Mutnovsky, Gorely and Opala), as well as a number of dormant and extinct stratovolcanoes, monogenic cones and large calderas. Furthermore, it contains the Malko-Petropavlovsk fracture zone (MPZ), which marks the boundary between two distinct subduction regimes to the south and to the north. We present a new seismic tomography model for this area, which was constructed based on the joint use of data of the Kamchatkan permanent seismic stations and a temporary network installed in the region in 2019–2020. A series of synthetic tests have demonstrated fair resolution of the derived seismic velocity structures in the crust and in the mantle wedge down to ~150 km. The distributions of the P and S wave velocities, and especially the Vp/Vs ratio, clearly highlight the connection between the volcanic centers in Central Kamchatka and the subducting slab. At depths below 40 km depth, we observe two large low-velocity anomalies centered below Zhupanovsky and Mutnovsky volcanoes and covering all other volcanoes in the area. In the vertical sections, the corresponding anomalies of high Vp/Vs ratio have mushroom shapes with the heads spreading along the bottom of the crust, which probably represent the underplating of magma material that feeds the volcanoes of the groups. The tomography results also reveal some important tectonic features, such as a V-shaped fault system in the Avacha Graben, which is the part of the MPZ.

Distal volcanic tephras in soil sections and lake sediments in the Dvuh-yurtochnoe (Two-Yurts) lake area, central Kamchatka, were investigated in order to provide a chronological framework for the reconstruction of late Quaternary landscape development. Mineralogical and geochemical data point to sources from 5 volcanoes. Ten tephra layers were identified and correlated to known eruptive events. The ages were corroborated by radiocarbon dating of the soil sections around Two-Yurts lake. These findings allow the reconstruction of regional paleoenvironmental change, recorded in the soil sections around Two-Yurts lake. During the Last Glacial Maximum (LGM) time, the area was affected by glacial advances that produced the glacial moraines at the eastern outlet of the lake. A large landslide, ca. 15,000–18,000 14C BP, dammed the valley and led to formation of Two-Yurts lake. Several more landslide events can be recognized in the Holocene, and one affected Two-Yurts lake ca. 3000 14C BP. This event produced a “tsunami”, documented by poorly sorted deposits with rounded pebbles in the onshore sections around the lake. In contrast to the soil sections, tephras buried in the “soupy” lacustrine sediments of Two-Yurts lake are not well preserved and show inconsistent age-depth relationships compared to those suggested by radiocarbon dating, due to sinking through the lake sediments. Nevertheless, tephrochronological data revealed the strong impact of terrestrial landslides on lake sedimentation.

Der Geologe Karl von Ditmar erkundete von 1851 bis 1855 im Auftrag der russischen Regierung die Bodenschätze Kamčatkas. Dabei erforschte er das Land und seine Bevölkerung aber weit über diesen Autrag hinaus, was seine eindrucksvollen Reisebeschreibungen zeigen. So verbrachte er im Sommer 1853 als erster Forscher längere Zeit bei den Korjaken auf der Halbinsel Tajgonos. Der 1890 erschienene erste Teil seines Werkes enthält den ausführlichen Bericht seiner Reise nach den Tagebüchern, ein getrennt erscheinender zweiter Teil die systematische Darstellung der Natur und der Geschichte Kamčatkas.