Gorely volcano is located 65 km southwest of Petropavlovsk-Kamchatsky.

It is a typical shield volcano, 1829 m high, up to 28 km across the base. In the center of the caldera, a modern edifice: three closely spaced cones forming a ridge extending northwest for 6 km. Eleven superimposed crater cones at the top and over 40 slag cones at the sides form an exotic shape of the volcano. The edifice consists of pyroclastic basalt and basaltic andesite. The volcano is located on a volcanic plateau.

The activity of Gorely volcano can be historically listed since 19th century. The four explosive eruptions from summit crater occured: in 1828, 1832, 1855, and 1869. In the 20th century, seven eruptions occured in 1929, 1930, 1931, 1947, 1961, 1980-1981, and 1984-1986.

During the eruption of 1980-1981, up to 70,000 tons of material were erupted, including 25,000 tons of juvenile and 45,000 tons of resurgent, covering an area of 500 sq. km. During the last 1984-1986 eruption, the height of gas-ash clouds reached 600 m over the rim of the crater, more than 1,500 thous. tons of ash were ejected. A more violent explosive eruption can happen in near future.

Photo by Marco Fulle: The second and active summit crater of Gorely, with a boiling and acid green lake seen from SW.

Mutnovsky volcano

Mutnovsky volcano is one of the most picturesque and compositionally complex volcanoes in southern Kamchatka. It is located 70 km south of Petropavlovsk-Kamchatsky.

The Mutnovsky volcano is formed by four-intergrown, successively formed stratovolcanoes. The highest point of the Mutnovsky is 2323 m above sea level. The active vent of Mutnovsky volcano is 15 km southeast of the main crater of Gorely volcano.

All four stratovolcanoes forming Mutnovsky developed similarly. After reaching a certain critical point of height and volume, each cone terminated its activity. The magma-feeding chamber shifted, and the cycle repeated resulting in the formation of another cone. During the 20th century, there were five explosive eruptions: 1904, 1916-17, 1927-29, 1839-40, and 1960.

While visiting the crater by walk you will see the processes of modern hydrothermal activity and mineral formation: gas and steam jets; boiling mud pots; hot acid streams; and thermal areas with different minerals: native sulfur, alunite, opal, hematite, ammonium chloride, laurencite, molysite, thenardite, aphthitalite, millosevichite, gypsum, alunogen, halotrichite, pyrite, melnikovite-pyrite, marcasite, cinnabar, chalcopyrite, and pyrrhotite.

Photo by Marco Fulle: Inside the Mutnovsky crater looking at SW. Active fumaroles melt the giant glacier.

Avachinsky volcano

Avachinsky is a typical volcano of the Somma-Vesuvius type. It is located 30 km north of Petropavlovsk-Kamchatsky. The absolute height is 2751 m, while the height of the somma is 2317 m in its eastern part. The eccentrical active volcano rises over a somma edge for 400-1000 m. At the base, the cone is about 4 km in diameter, and is crowned by a crater 350 m in diameter.

During the last 250 years eruptions were in 1737, 1772, 1779, 1789, 1827, 1837, 1855, 1878, 1881, 1894-1895, 1901, 1909, 1926-1927, 1938, 1945, and 1991. One of the biggest was the ash eruption of June 15-16, 1779, when ash dusted the ships of Cook's squadron that were at the roadstead in the Avacha bay. A pyroclastic flow in 1894-1895 was preceded by an earthquake while the eruption of 1926 poured out a short lava flow on the southern slope below the crater. Lava flow also happened in 1827,1901,1909, and 1938.

The last eruption in Jan 1991 was explosive with lava flow. The lava fill completly the crater with depth 220 m and 350 m in diameter. Today in the crater many active fumaroles can be observed.

Photo by Marco Fulle: The S side of the Avachinsky top crate filled by the black andesitic lava of the April 1991 eruption.

Karymsky volcano

Karymsky is a stratovolcano located in the center of a 12 km² caldera. It is one of the most active volcanoes of the Eastern zone, with more than 20 eruptions in the short historical record, starting in 1771.

Most of the eruptions are moderate in size and of andesitic composition. The volcano has been in eruption since New Year's Day 1996. After an initial phase at the Lake, with very interesting simultaneous emission of rhyolite and basalt, the activity is now confined in the summit crater, where explosions of andesitic material follow themselves at short (about 5 minutes) intervals.

Some photos of such explosions, taken during an adventurous helicopter flight, were kindly provided by two participants to the workshop:

Photo 1 and Photo 2, by Olivier Jaquet

Photo 3 and Photo 4, by Marco Fulle

The volcano had been relatively quiet since 1982, following a decade of frequent eruptive activity.

Photo by Marco Fulle: The house of volcanologists in the Karymsky caldera. In the background, erupting Karymsky seen from SE produces an ash eruption.