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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.
Lava domes are formed by the extrusion of viscous felsic magma. They can form prominent rounded protuberances, such as at Valles Caldera. As a volcano extrudes silicic lava, it can form an inflation dome or endogenous dome, gradually building up a large, pillow-like structure which cracks, fissures, and may release cooled chunks of rock and rubble.
Lava domes, also called dome volcanoes, have steep convex sides built by slow eruptions of highly viscous lava, for example, rhyolite. [2] They are sometimes formed within the crater of a previous volcanic eruption, as in the case of Mount St. Helens , but can also form independently, as in the case of Lassen Peak .
The lava dome likely formed before the lava flows erupted, suggested by its steep western side and the appearance of rock from the dome on the western lava flow. The dome's 20-foot (6 m) deep depression may have formed when the dome's top collapsed as lava moved out of the volcano during the eruption of the two flows. [19]
Lava domes are common features on volcanoes around the world. Lava domes are known to exist on plate margins as well as in intra-arc hotspots, and on heights above 6000 m and in the sea floor. [1] Individual lava domes and volcanoes featuring lava domes are listed below.
A lava spine (or lava spire) is a vertical growth of solid lava that is forced from a volcanic vent. A lava spine can either be formed by viscous lava slowly being pushed out of the vent, or by magma that has solidified within the vent before being pushed out.
Between 385,000 and 315,000 years ago, volcanic activity in the Lassen volcanic center shifted dramatically from building andesitic stratovolcanoes to producing lava domes made of dacite. These eruptions formed the Lassen dome field, staged as andesite lava flows surrounding two sequences of dacitic lava domes. The first sequence of lava domes ...
Effusive eruption differs from explosive eruption, wherein magma is violently fragmented and rapidly expelled from a volcano. Effusive eruptions are most common in basaltic magmas, but they also occur in intermediate and felsic magmas. These eruptions form lava flows and lava domes, each of which vary in shape, length, and width. [2]