Лава күмбездері: құрылысы, қауіптері және геологиялық ерекшеліктері

Roughly circular protrusion from slowly extruded viscous volcanic lava

In volcanology, a lava dome is a circular, mound shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions on Earth form lava domes. The characteristic dome shape is attributed to high viscosity that prevents the lava from flowing very far. This high viscosity can be obtained in two ways: by high levels of silica in the magma, or by degassing of fluid magma. Since viscous basaltic and andesitic domes weather fast and easily break apart by further input of fluid lava, most of the preserved domes have high silica content and consist of rhyolite or dacite. Existence of lava domes has been suggested for some domed structures on the Moon, Venus, and Mars,

Lava domes evolve unpredictably, due to non linear dynamics caused by crystallization and outgassing of the highly viscous lava in the dome's conduit. Domes undergo various processes such as growth, collapse, solidification and erosion. Lava domes grow by endogenic dome growth or exogenic dome growth. The former implies the enlargement of a lava dome due to the influx of magma into the dome interior, and the latter refers to discrete lobes of lava emplaced upon the surface of the dome. Spines and lava flows are common extrusive products of lava domes. If part of a lava dome collapses and exposes pressurized magma, pyroclastic flows can be produced. Other hazards associated with lava domes are the destruction of property from lava flows, forest fires, and lahars triggered from re mobilization of loose ash and debris. Lava domes are one of the principal structural features of many stratovolcanoes worldwide. Lava domes are prone to unusually dangerous explosions since they can contain rhyolitic silica rich lava. Characteristics of lava dome eruptions include shallow, long period and hybrid seismicity, which is attributed to excess fluid pressures in the contributing vent chamber. Other characteristics of lava domes include their hemispherical dome shape, cycles of dome growth over long periods, and sudden onsets of violent explosive activity. The average rate of dome growth may be used as a rough indicator of magma supply, but it shows no systematic relationship to the timing or characteristics of lava dome explosions. Gravitational collapse of a lava dome can produce a block and ash flow.

A cryptodome (from the Greek κρυπτός, , "hidden, secret") is a dome shaped structure created by accumulation of viscous magma at a shallow depth. One example of a cryptodome was in the May 1980 eruption of Mount St. Helens, where the explosive eruption began after a landslide caused the side of the volcano to collapse, leading to explosive decompression of the subterranean cryptodome.

A lava spine or lava spire is a growth that can form on the top of a lava dome. A lava spine can increase the instability of the underlying lava dome. A recent example of a lava spine is the spine formed in 1997 at the Soufrière Hills Volcano on Montserrat.

Coulées (or coulees) are lava domes that have experienced some flow away from their original position, thus resembling both lava domes and lava flows. There is another prominent coulée flow on the flank of Llullaillaco volcano, in Argentina, and other examples in the Andes.

+ Lava domes Name of lava dome Country Volcanic area Composition Last eruptionor growth episode Chaitén lava dome Chile Southern Volcanic Zone Rhyolite 2009 Ciomadul lava domes Romania Carpathians Dacite Pleistocene Cordón Caulle lava domes Chile Southern Volcanic Zone Rhyodacite to Rhyolite Holocene Galeras lava dome Colombia Northern Volcanic Zone Unknown 2010 Katla lava dome Iceland Iceland hotspot Rhyolite 1999 onwards Lassen Peak United States Cascade Volcanic Arc Dacite 1917 Black Butte (Siskiyou County, California) United States Cascade Volcanic Arc Dacite 9500 BP Bridge River Vent lava dome Canada Cascade Volcanic Arc Dacite ca. 300 BCLa Soufrière lava domeSaint Vincent and the GrenadinesLesser Antilles Volcanic Arc2021 Mount Merapi lava dome Indonesia Sunda Arc Unknown 2010 Nea Kameni Greece South Aegean Volcanic Arc Dacite 1950 Novarupta lava dome United States Aleutian Arc Rhyolite 1912 Nevados de Chillán lava domes Chile Southern Volcanic Zone Dacite 1986 Puy de Dôme France Chaîne des Puys Trachyte c. 5760 BC Santa María lava dome Guatemala Central America Volcanic Arc Dacite 2009 Sollipulli lava dome Chile Southern Volcanic Zone Andesite to Dacite 1240 ± 50 years Soufrière Hills lava dome Montserrat Lesser Antilles Andesite 2009 Mount St. Helens lava domes United States Cascade Volcanic Arc Dacite 2008 Torfajökull lava dome Iceland Iceland hotspot Rhyolite 1477 Tata Sabaya lava domes Bolivia Andes Unknown ~ Holocene Tate iwa Japan Japan Arc Dacite Miocene Tatun lava domes Taiwan Andesite 648 Valles lava domes United States Jemez Mountains Rhyolite 50,000 60,000 BP Wizard Island lava dome United States Cascade Volcanic Arc Rhyodacite 2850 BC