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The Yellowstone hotspot is a volcanic hotspot in the United States responsible for large scale volcanism in Idaho, Montana, Nevada, Oregon, and Wyoming, formed as the North American tectonic plate moved over it.
The fractures take the form of a set of concentric cones dipping at a relatively shallow angle into the magma chamber. [3] [13] When the caldera is subsequently emptied by explosive volcanic activity, the roof of the magma chamber collapses as a plug of rock surrounded by a ring fracture. Magma rising into the ring fracture produces a ring dike.
A supervolcano is a volcano that has had an eruption with a volcanic explosivity index (VEI) of 8, [1] the largest recorded value on the index. This means the volume of deposits for such an eruption is greater than 1,000 cubic kilometers (240 cubic miles).
Volcanic activity started at Lyttelton Harbour (c.11 Ma) [12] then extended through the Mount Herbert Volcanic Group to Akaroa Harbour (c.9 Ma). [12] During the latter phase of the volcano it was simultaneous active from both its major magma chambers, at Akaroa and Lyttelton. The complex geochemically evolved over time and has cyclic eruptive ...
Some of these volcanic rocks bear traces of hydrothermal alteration. In some places the layers of volcanic rocks are as thick as 100 m (330 ft). [27] There may be other volcanoes buried in the sediment pile; [28] at least four separate aeromagnetic anomalies have been found at the Salton Buttes, and these may be signs of buried volcanoes. [11]
A volcano tectonic earthquake or volcano earthquake is caused by the movement of magma beneath the surface of the Earth. [1] The movement results in pressure changes where the rock around the magma has a change in stress. At some point, this stress can cause the rock to break or move. This seismic activity is used by scientists to monitor ...
Scientists believed that pulses of magma mixed together in the magma chamber before climbing upward—a process estimated to take several thousands of years. Columbia University volcanologists found that the eruption of Costa Rica's Irazú Volcano in 1963 was likely triggered by magma that took a nonstop route from the mantle over just a few ...
Some of these triggers operate only under limited conditions. For example, sector collapse (where part of the flank of a volcano collapses in a massive landslide) can trigger eruption only of a very shallow magma chamber. Magma differentiation and thermal expansion also are ineffective as triggers for eruptions from deep magma chambers. [14]