& # 39; The largest volcano in the world & # 39; loses its title after scientists discover that it was not caused by a single eruption
- Tamu Massif is located in the Shatsky Rise, about 990 miles (1,600 km) east of Japan
- Scientists from the University of Houston proclaimed the largest shield volcano in 2013
- But after drilling into the cooled magma, they discovered magnetic anomalies
- Now believe it was formed by spreading on the seabed caused by three ocean ridges
& # 39; The world's largest volcano has been stripped of its title after scientists discovered it was formed by spreading on the seabed instead of a single eruption.
Tamu Massif in the Shatsky Rise, about 990 miles (1,600 km) east of Japan, was named the largest shield volcano by scientists from the University of Houston in 2013.
But after reclassifying the volcano, Mauna Loa in Hawaii, which covers 2,000 square kilometers – only two percent of the size of Tamu Massif – has received the title.
The extinct underwater volcano is about 120,000 square miles (310,000 square kilometers) in size and was formed around 145 million years ago before it died out several million years later.
It was formed above an area where three tectonic plates meet, and researchers assumed it was created by a huge burst of a single plume head.
To prove their theory, the group looked at magnetic anomalies in the magma that formed the 400-mile-wide volcano.
The extinct underwater volcano Tamu Massif (photo) has been stripped of its title of & # 39; the world's largest volcano & # 39; after scientists discovered it was formed by spreading on the seabed instead of a single eruption
WHERE ARE THE BIGGEST VOLCANS OF THE WORLD?
& # 39; The world's largest volcano is Mauna Loa in Hawaii, with an area of 2000 square kilometers. It last broke out in 1984, but is still active.
Mount Kilimanjaro in Tanzania is one of & # 39; the world's largest dormant volcanoes at 668 square kilometers (1668 square kilometers). It is a stratovolcano that consists of three different volcano cones. The last major eruption was around 360,000 years ago.
The Ichinsky volcano is located on the Russian Kamchatka peninsula. It is also a strata volcano but has only two lava cones. Ichinsky has a volume of 450 cubic kilometers.
The Earth's magnetic poles have not always been in the same place and have been exchanged 183 times in the last 83 million years.
Magma has magnetic material in it, and when it cools, it aligns with the poles in that period.
The researchers drilled in different parts of the volcano, collected paleomagnetic data and compared it with theoretically where it should be aligned.
If it had been formed by an enormous eruption, there would be no anomalies, because the magma would have been formed at the same time and would therefore have the same poles.
Scientists discovered that this was in fact not the case, making it impossible for Tamu Massif to be formed by a single eruption.
Chief author William Sager, a professor in the Earth and Atmospheric Sciences department at the University of Houston, told Newsweek: & # 39; If it has formed in a short time (one polarity period), it will have a coherent overall anomaly.
& # 39; If it arose during multiple polarity periods, the deviation must be irregular. Lava flows that travel long distances should destroy the magnetic stripes. & # 39;
The paper, published in Nature Geoscience, suggests the huge volcano – which is 6,500 feet below the sea surface – was instead formed by the spread of the seabed on mid-ocean ridges.
Tamu Massif is located in the Shatsky Rise, about 990 miles (1,600 km) east of Japan and is about 120,000 square miles (310,000 square kilometers) in size and was formed around 145 million years ago before it died out a few million years later.
Researchers have discovered that the volcano, which is about 310,000 square kilometers in size, was formed instead when magma was pushed up in an area surrounded by three tectonic plates and causing the seabed to rise above
As the three tectonic plates moved, magma was pushed up against the crust above without bursting through.
This process forced the seabed to spread and form parts of the volcano.
The newspaper concludes that although Tamu Massif is indeed huge, it is not a shield volcano, and is in fact a mid-oceanic edge system.
Mauna Loa in Hawaii, which covers 2,000 square kilometers – only two percent the size of Tamu Massif – has regained the title of the world's largest shield volcano.
HOW DOES THE MAGNETIC FIELD OF THE EARTH WORK?
The magnetic field of our planet is supposed to be generated deep in the core of the earth.
At the heart of the earth is a solid core, two-thirds the size of the moon, made primarily of iron.
At 5,700 ° C this iron is just as hot as the surface of the sun, but the pressure caused by gravity prevents it from liquefying.
Around this, the outer core is a 1,242 mile (2,000 km) thick layer of iron, nickel, and small amounts of other metals.
The metal is liquid here, due to the lower pressure than the inner core.
Differences in temperature, pressure and composition in the outer core cause convection currents in the molten metal as cool, dense matter pits and hot matter rises.
The & # 39; Coriolis & # 39; force caused by the rotation of the earth also causes swirling vortices.
This flow of liquid iron generates electric currents, which in turn create magnetic fields.
Charged metals that pass through these fields create electrical currents and so the cycle continues. This self-sustaining loop is known as the geodynamo.
The spiral formation caused by the Coriolis force means that the individual magnetic fields are roughly aligned in the same direction, their combined effect adding up to produce one huge magnetic field that engulfs the planet.
Magnetic north floats around and every few hundred thousand years the polarity turns so that a compass points south instead of north.
The strength of the magnetic field is also constantly changing and is currently showing signs of significant attenuation.
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