While all of the continents were formed by the splitting of the supercontinent Pangaea, Iceland emerged because of a divergent, spreading, boundary between two plates known as the Eurasian and North American tectonic plates (Fig. 1). As these plates move away from each other, Iceland is torn down at its center, which causes both sections to move apart. Because of these moving plates, magma rises from the asthenosphere below, providing molten rock for the volcanoes and heat for the geysers that are located there. Iceland is known as the best studied, large-volume, active volcanic region in the world. It features the largest exposure of any hotspot at a spreading ridge, and is possibly attributed to a thermal plume in the mantle. Spanning the Mid-Atlantic Ridge, Iceland was first appearing over the ocean surface about 16 to 18 million years ago. The current plate boundary consists of a series of volcanic and seismic zones (Fig. 1) that have developed and reorganized in a complex manner due to interaction of Iceland Mantle Plume. …show more content…
The mantle plume is located east of the ridge channel, but the eruptive belt tends to follow the plume, and it's there that volcanic activity is greatest.” Iceland is currently known as one of most active hotspots on Earth with a plume head of approximately 1000 kilometers in diameter. There are also many different types of geologically active volcanoes in Iceland. One of them just erupted recently. Bardabunga’s eruption took place from August 29, 2014 to February 27, 2015. This eruption spewed large volumes of sulphur dioxide and hugely impacted the air quality of
...e than 30 volcanoes that have erupted over the past 300,000 years in the Lassen Peak volcanic area.
Mauna Loa is located on a hot spot in the Pacific Ocean. It is not near a plate boundary, in fact it is 3,200 km from the nearest plate boundary, and is situated in the middle of the Pacific tectonic plate. This is actually a rarity, as 90% of volcanoes are along a tectonic plate boundary. A hot spot occurs where long, stationary vertical pools of magma rise up and towards the plate. Movement of the tectonic plates above the hot spot created Mauna Loa, along with the other Hawaiian volcanoes. The older Hawaiian Islands were once above this stationary hot spot, but have been carried northwest by the slowly moving Pacific plate. As the plate moves, it carries the previously formed, older, volcanoes with it, creating a trail of younger, new volcanoes behind. The islands are lined up along the Hawaiian Ridge-Emperor Seamounts chain, which is 3,750 miles and includes Kauai, Maui, Oahu and Hawai’i, from north to south, respectively. There are around 80 volcanoes in this chain; most of them underwater, consequently the term seamount refer to submarine volcanoes. Three volcanoes of Hawai’i, Mauna Loa, Kilauea and Loihi seamount, are all currently sharing the Hawaiian hot spot. Although, recent evidence has shown that all three volcanoes use have separate plumbing systems to expel the lava from the pool of magma deep below them. It has also been suggested that Loihi is slowly moving Mauna Loa from the center of the island, thus shifting directly over the hot spot. The closer to the hot spot a volcano is, the more active it will be. The Hawaiian hot spot has laid down layers of lava, building up enormous islands from the ocean floor.
Iceland is known for its volcanic activity. A few years before Heimaey erupted; a nearby sub oceanic eruption formed the new island of Surtsey. The town of Vestmannaeyjar already had an extinct volcano on its outskirts, the volcano was known as Helgafell. It was thought to have been extinct for several hundred years. In January 1973 a new fissure opened up a few hundred yards from the extinct volcano. It went clear across the island and into the ocean on both sides. Boats escaping the harbor saw red magma under the water, and sub oceanic power and water lines from the mainland were broken by the eruption. In the initial eruption a curtain of lava 500 feet erupted from the fissure, after a few days the eruption was mostly from a single vent, with a cinder cone 300 feet tall. The lava flows from the eruption were a viscous slow moving basaltic magma. Average speeds for the lava flows were 3 to 9 yards a day. These relatively slow speeds are what made it possible to try and cool and divert the lava.
Volcanism is a major part of the Galapagos and their formation. The island chain is positioned on the Nazca Plate, which is subducting beneath the South American Plate at a geologically rapid pace of 2.5 inches per year. In addition, this Nazca Plate is located directly on top of the Galapagos Hotspot. It is here that mantle plumes melt Earth’s crust, creating volcanoes as a product. The oldest island was first shaped by this ...
Basalt forms due to the partial melting of the layer of the mantle called the asthenosphere. The asthenosphere is the plastic zone of the mantle beneath the rigid lithosphere. Mantle plumes coming from the mesosphere can cause the asthenosphere to melt with heat or even if pressure decreases, which is called decompression melting (Richard 2011). The magma that forms from this melting is mafic magma that solidifies once it reaches the earth’s surface and cools quickly. The above process mainly occurs mainly during intraplate igneous activity which is the main explanation for volcanic activity that occurs a long distance away from a plate boundary. If the tectonic plate above the mantle plume is moving it can create a string of volcanic activity such as in Hawaii. See Fig 2.
...t of laurasia, just like most of the other plates. North America,Europe, and Green land all used to be connect because of Pangea ( as mentioned earlier). But when everything started to separate, first europe, then green land, and lastly the North American plate. After pangea was no more and the plates all started moving, the continents started going their own ways, there fore putting the continents where they are today.
Stories about volcanoes are captivating. Myths come in different versions, but all of them are capable of capturing yours, and everybody’s imagination.
Convection currents deep in the mantle of the earth, begin to well up towards the surface. As the pressure increases, it sets the crustal plates in motion. There are different kinds of mountains - Volcanic, Folded, Fault-block, and Dome mountains. Volcanic mountains are formed when magma comes up through cracks in the Earth’s crust and explodes out of lava and ash. The Hawaiian volcanoes, Mt. Hood, Mt. Etna, Vesuvius, and Mt. Saint Helens is an example of volcanic mountains.
The most dramatic expression of tectonism is mountainous topography, which is either generated along continental margins by collisions between the slablike plates that make up the Earth's lithosphere or formed somewhat farther inland by rifting and faulting. Far more subtle tectonic expressions are manifested by the vast continental regions of limited relief and elevation affected by gentle uplift, subsidence, tilting, and warping. The denudational processes act upon the tectonic "stage set" and are able to modify its features in a degree that reflects which forces are dominant through time. Volcanism as a syn-tectonic phenomenon may modify any landscape by fissure-erupted flood basalts capable of creating regional lava plateaus or by vent eruptions that yield individual volcanoes.
Apart from the tectonic plates spreading, the Mid-Atlantic Ridge is also the site of volcanic activity and earthquakes. A day later my tour guide stumbles onto the Azores plateau which is an area of thickened oceanic crust and is thought to be formed from the Azores hotspot. The oceanic plateaus are created by magma trenches or plumes. 28°N and 29° W.
Volcanoes can be one of the most destructive forces on Earth. It is estimated that some
From modern examples and records we know that volcanic activity can set of a chai...
The continental drift theory and plate tectonics theory was first put forward by the German geologist and meteorologist Alfred Wegener at the beginning of the 20th century. He proposed that there was a single continental in 200 million years ago, and the Earth’s crust slowly separate to pieces by the centrifugal pseudo force because of the rotation of the Earth. On the basis of plate tectonics theory there are two components in the Earth which are lithosphere and asthenosphere, the upper layer is lithosphere and the lower layer is asthenosphere. However, the lithospheric plates slowly move in a complex pattern, and the flow velocity is about 2-10 cm/year (Adam T. Mansur, 2010). There are there different kinds of plate boundaries of movement due to continental drift theory: divergent boundaries, convergent boundaries and transform boundaries as figure 2 shown.
The concurrent convective circulations in the mantle leads to some segments of the mantle moving on top of the outer core which is very hot and molten in nature. This kind of movement in different segments occurs as tectonic plates. These tectonic plates are basically seven on the earth surface as major ones, although, several small ones exist also. The plates motions are characterized by varying velocities, this variance results to sub sequential collision of two plates (leading to formation of a mountain in a convergent boundary), drift of two plates (leading to formation of rifts in a divergent boundary), or parallel movement in a transform boundary(Webcache 3).