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Lava Dome | John Seach
A lava dome is a mound of volcanic rock extruded from a volcano. The lava piles into a heap rather than flowing away. Diameters of domes range from a few metres to several kilometers. They can be up to 1000 m high.
Types of Lava Domes
1) Spiny domes (Pelean).
These are the steepest domes with a smooth surface and vertical spines.
2) Blocky domes.
These are composed of distince lobes which erupt sequentially from a vent.
3) Platy domes.
These have a low profile which is determined by local topography.
One of the main hazard from domes are explosions and collapse. Viscous lava in the dome can allow high pressure to build, resulting in explosive eruptions. Dome collapse under the weight of gravity can result in pyroclastiv flows, one of the most deadly types of volcanic eruption.
Causes of partial dome collapse include rain, gas overpressurisation, and over-steepening.
Examples of volcanoes with domes
Mt St Helens (USA), Merapi (Indonesia), Gunung Ranakah (Indonesia), Nigata-yake-yama (Japan), Nii-jima (Japan), Nipesotsu-upepesank (Japan), Augustine (Alaska), El Chichon (Mexico), Micotrin (Caribbean), Methana (Greece), and Soufriere Hills (Montserrat).