Major Volcanic Zones - World | Oxford Student ATLAS: Maps & Tests - UPSC PDF Download

 Page 1


Major Volcanic Zones
World Distribution of Volcanoes
Introduction
Volcanoes are fascinating natural phenomena characterized by breaks or cracks
on the Earth's surface that allow the flow of hot lava, volcanic ash, and gases.
These eruptions occur due to the presence of a magma chamber within the
volcanoes. Volcanic structures primarily exist in regions where tectonic plates
diverge or converge, leading to the accumulation and solidification of volcanic
materials that form majestic volcanic mountains. One of the most common types
of volcanoes is the symmetrical and cone-shaped "cinder cone volcano."
Volcanoes in the Mid-Atlantic Belt
The Mid-Atlantic Ridge (MAR), also known as the Mid-Atlantic Belt, is an extensive
range of volcanic mountains spanning over 16,000 kilometers from the Arctic
(Gakkel Ridge) to the Antarctic (Bouvet Triple Junction) regions. Although the
majority of the Mid-Atlantic Belt is submerged underwater, with approximately
90% of its volcanic mountain ranges at a depth of around 2,500 meters, its axial
part is visible in Iceland. The belt is situated at the convergence point of tectonic
Page 2


Major Volcanic Zones
World Distribution of Volcanoes
Introduction
Volcanoes are fascinating natural phenomena characterized by breaks or cracks
on the Earth's surface that allow the flow of hot lava, volcanic ash, and gases.
These eruptions occur due to the presence of a magma chamber within the
volcanoes. Volcanic structures primarily exist in regions where tectonic plates
diverge or converge, leading to the accumulation and solidification of volcanic
materials that form majestic volcanic mountains. One of the most common types
of volcanoes is the symmetrical and cone-shaped "cinder cone volcano."
Volcanoes in the Mid-Atlantic Belt
The Mid-Atlantic Ridge (MAR), also known as the Mid-Atlantic Belt, is an extensive
range of volcanic mountains spanning over 16,000 kilometers from the Arctic
(Gakkel Ridge) to the Antarctic (Bouvet Triple Junction) regions. Although the
majority of the Mid-Atlantic Belt is submerged underwater, with approximately
90% of its volcanic mountain ranges at a depth of around 2,500 meters, its axial
part is visible in Iceland. The belt is situated at the convergence point of tectonic
Major Volcanic Zones
plates forming the floor of the Atlantic Ocean. The molten lava slowly spreads on
the ocean floor, giving the ridge its characteristic "slowly spreading" nature.
The Mid-Atlantic Belt extends from the Arctic Ocean to the southern tip of Africa,
with volcanic mountain ranges occasionally reaching above sea level, forming
island groups like St. Helena, Tristan da Cunha, The Azores, and Ascension. The
slow-spreading process of the Mid-Atlantic Belt contributes to the gradual
expansion of the Atlantic floor, advancing at a rate of 1-10 centimeters per year.
Circum Pacific Ring of Fire
The Circum Pacific Ring of Fire, also known as the Pacific Ring of Fire, Girdle of
Fire, Rim of Fire, or Circum-Pacific Belt, stretches approximately 40,000
kilometers and is 500 kilometers wide. This region is renowned for its frequent
volcanic eruptions and earthquakes. The Pacific Ring of Fire encircles the rim of
the Pacific Ocean and extends across North America, South America, Kamchatka,
and several western Pacific islands. It is formed due to the tectonic movement of
plates beneath and around the Pacific Ocean.
Unlike a single continuous mass of volcanic structures, the Pacific Ring of Fire
consists of individual volcanoes distributed throughout the belt, with eruptions
occurring at different times and locations. Some noteworthy facts about the
Pacific Ring of Fire include:
· It is estimated that the Circum-Pacific belt consists of approximately 850-
1000 volcanoes that have been active within the past 11,700 years.
· The region witnessed the world's fourth-largest volcanic explosion.
· More than 350 volcanic structures in the Circum-Pacific belt have been
consistently active since historical times.
· Inactive volcanoes in the Pacific belt, which have been dormant for the past
millennium, also exist.
· The Pacific belt is home to the majority of the Earth's visible volcanic
summits above sea level.
· Ojos del Salado, located in the Circum-Pacific belt, holds the title of the
world's highest active volcano.
· Nearly 90% of the world's earthquakes and 81% of the most devastating
earthquakes occur in the Pacific Ring of Fire.
Notable volcanoes within the Pacific Ring of Fire include Agung, Sinabung,
Dukono, Mount Tambora (known for significant volcanic activity in 1815), and
Mount Pinatubo (famous for its major eruption in 1991).
Page 3


Major Volcanic Zones
World Distribution of Volcanoes
Introduction
Volcanoes are fascinating natural phenomena characterized by breaks or cracks
on the Earth's surface that allow the flow of hot lava, volcanic ash, and gases.
These eruptions occur due to the presence of a magma chamber within the
volcanoes. Volcanic structures primarily exist in regions where tectonic plates
diverge or converge, leading to the accumulation and solidification of volcanic
materials that form majestic volcanic mountains. One of the most common types
of volcanoes is the symmetrical and cone-shaped "cinder cone volcano."
Volcanoes in the Mid-Atlantic Belt
The Mid-Atlantic Ridge (MAR), also known as the Mid-Atlantic Belt, is an extensive
range of volcanic mountains spanning over 16,000 kilometers from the Arctic
(Gakkel Ridge) to the Antarctic (Bouvet Triple Junction) regions. Although the
majority of the Mid-Atlantic Belt is submerged underwater, with approximately
90% of its volcanic mountain ranges at a depth of around 2,500 meters, its axial
part is visible in Iceland. The belt is situated at the convergence point of tectonic
Major Volcanic Zones
plates forming the floor of the Atlantic Ocean. The molten lava slowly spreads on
the ocean floor, giving the ridge its characteristic "slowly spreading" nature.
The Mid-Atlantic Belt extends from the Arctic Ocean to the southern tip of Africa,
with volcanic mountain ranges occasionally reaching above sea level, forming
island groups like St. Helena, Tristan da Cunha, The Azores, and Ascension. The
slow-spreading process of the Mid-Atlantic Belt contributes to the gradual
expansion of the Atlantic floor, advancing at a rate of 1-10 centimeters per year.
Circum Pacific Ring of Fire
The Circum Pacific Ring of Fire, also known as the Pacific Ring of Fire, Girdle of
Fire, Rim of Fire, or Circum-Pacific Belt, stretches approximately 40,000
kilometers and is 500 kilometers wide. This region is renowned for its frequent
volcanic eruptions and earthquakes. The Pacific Ring of Fire encircles the rim of
the Pacific Ocean and extends across North America, South America, Kamchatka,
and several western Pacific islands. It is formed due to the tectonic movement of
plates beneath and around the Pacific Ocean.
Unlike a single continuous mass of volcanic structures, the Pacific Ring of Fire
consists of individual volcanoes distributed throughout the belt, with eruptions
occurring at different times and locations. Some noteworthy facts about the
Pacific Ring of Fire include:
· It is estimated that the Circum-Pacific belt consists of approximately 850-
1000 volcanoes that have been active within the past 11,700 years.
· The region witnessed the world's fourth-largest volcanic explosion.
· More than 350 volcanic structures in the Circum-Pacific belt have been
consistently active since historical times.
· Inactive volcanoes in the Pacific belt, which have been dormant for the past
millennium, also exist.
· The Pacific belt is home to the majority of the Earth's visible volcanic
summits above sea level.
· Ojos del Salado, located in the Circum-Pacific belt, holds the title of the
world's highest active volcano.
· Nearly 90% of the world's earthquakes and 81% of the most devastating
earthquakes occur in the Pacific Ring of Fire.
Notable volcanoes within the Pacific Ring of Fire include Agung, Sinabung,
Dukono, Mount Tambora (known for significant volcanic activity in 1815), and
Mount Pinatubo (famous for its major eruption in 1991).
Major Volcanic Zones
Intraplate Volcanoes
Intraplate volcanic activities occur within tectonic plates and are unrelated to
plate divergence or convergence. These regions, known as "hotspots," host active
volcanoes on the Earth's surface. Intraplate volcanoes form when mantle plumes
rise to the surface, spreading in the shape of a mushroom. These plume heads
typically have a diameter ranging from 500 to 1000 kilometers. The Hawaiian and
Emperor Seamount chains serve as prime examples of intraplate volcanoes.
Conclusion
The Circum-Pacific Ring of Fire and the Mid-Atlantic Belt are key regions hosting a
significant number of the world's active volcanoes. Almost 90% of major volcanic
activities worldwide occur within the Pacific belt, while the Hawaiian and Emperor
Seamount Chains showcase the most active intraplate volcanoes. These belts and
ridges encompass the vast majority of the Earth's volcanic distribution, along with
various other volcanic structures.