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Volcanoes known to have subglacial activity include: Mauna Kea in tropical Hawaii. There is evidence of past subglacial eruptive activity on the volcano in the form of a subglacial deposit on its summit. The eruptions originated about 10,000 years ago, during the last ice age, when the summit of Mauna Kea was covered in ice. [60]
Lahars are described as 'primary' or 'syn-eruptive' if they occur simultaneously with or are triggered by primary volcanic activity. 'Secondary' or 'post-eruptive' lahars occur in the absence of primary volcanic activity, e.g. as a result of rainfall during pauses in activity or during dormancy. [5] [6]
Volcano/complex Volcanic arc/belt, subregion, or hotspot Material volume (km 3) Age in Ka [1] Tephra or eruption name 6 Lolobau Island: Bismarck Volcanic Arc 50 12 caldera formation 6 Menengai: Great Rift Valley, Kenya < 25 12.3 Ruplax Tuff 6 Nevado de Toluca: Trans-Mexican Volcanic Belt: 20 12.5 Upper Toluca Pumice 6 Sakurajima: Kyūshū: 11 12.8
In the criteria of Volcanic Explosivity Index, recognizing an eruption as ultra-Plinian would make it at least VEI-5 or higher. [9] The threshold for ultra-Plinian eruptions is defined by an eruptive column height of 45 km (28 mi), [10] or 41 km (25 mi) more recently. [11]
Subglacial eruptions, those of ice-covered volcanoes, result in the interaction of magma with ice and snow, leading to meltwater formation, jökulhlaups, and lahars. Flooding associated with meltwater is a significant hazard in some volcanic areas, including Iceland, Alaska, and parts of the Andes.
In a volcanic eruption, lava, volcanic bombs, ash, and various gases are expelled from a volcanic vent and fissure. While many eruptions only pose dangers to the immediately surrounding area, Earth's largest eruptions can have a major regional or even global impact, with some affecting the climate and contributing to mass extinctions.
The GVP also documents the last 10,000 years of Earth's volcanism. The GVP database includes all known volcanoes that have erupted within the past 10,000 years, and includes listings of eruption dates, and eruptive phenomena; and lists of named volcanoes and volcanic features, with synonyms where they exist.
The central volcano of Bárðarbunga, the Veidivötn and Trollagigar fissures form one volcanic system, which extend about 100 km SW to near Torfajökull volcano and 50 km NE to near Askja volcano, respectively. The subglacial Loki-Fögrufjöll volcanic system located SW of Bárðarbunga volcano is also part of the Bárðarbunga volcanic system ...