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The mass of rock ejected during the eruption is usually between 10 2 and 10 6 tonnes [1] and contains a high proportion of non-juvenile material (> 50%). During active periods of volcanic activity, intervals between explosions vary from less than 1 minute (e.g. Anak Krakatoa) to about a day.
For example, the recovery time of ocean heat content of Pinatubo, which caused comparable radiative forcing to Krakatau, seems to be much shorter. This is because Pinatubo happened under a warm and non-stationary background with increasing greenhouse gas forcing. [7] However, its signal still could penetrate down to ~1000 m deep. [1]
Each process generates different rock; mid-ocean ridge volcanics are primarily basaltic, whereas subduction flows are mostly calc-alkaline, and more explosive and viscous. [55] Spreading rates along mid-ocean ridges vary widely, from 2 cm (0.8 in) per year at the Mid-Atlantic Ridge, to up to 16 cm (6 in) along the East Pacific Rise. Higher ...
The term volcanic ash is also often loosely used to refer to all explosive eruption products (correctly referred to as tephra), including particles larger than 2 mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the gases shatters the magma ...
In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when
Phreatic explosions can be accompanied by carbon dioxide or hydrogen sulfide gas-emissions. Carbon dioxide can asphyxiate at sufficient concentration; hydrogen sulfide acts as a broad-spectrum poison. A 1979 phreatic eruption on the island of Java killed 140 people, most of whom were overcome by poisonous gases. [3]
Diagram of Enceladus's south polar plumes, an example of explosive cryovolcanism, and Enceladus's internal ocean. Explosive cryovolcanism, or cryoclastic eruptions, is expected to be driven by the exsolvation of dissolved volatile gasses as pressure drops whilst cryomagma ascends, much like the mechanisms of explosive volcanism on terrestrial ...
Examples of extinct volcanoes are many volcanoes on the Hawaiian–Emperor seamount chain in the Pacific Ocean (although some volcanoes at the eastern end of the chain are active), Hohentwiel in Germany, Shiprock in New Mexico, US, Capulin in New Mexico, US, Zuidwal volcano in the Netherlands, and many volcanoes in Italy such as Monte Vulture.