A volcano is a special type of mountain through which heated and molten rocks, ash, and gas comes out from underground. This is a geographical process. The precise definition of volcano according to P.G. Worcester, “A volcano is a vent or opening, usually circular or nearly circular in form, through which heated materials consisting of gasses, water, liquid lava and fragments of rocks are ejected from the lightly heated interior to the surface of the earth”. And as per A. Holmes and D. L. Holmes,” A volcano is essentially a fissure or vent, communicating with the interior, from which flows of lava, fountains of incandescent spray or explosive bursts of gasses and volcanic ashes erupt at the surface”. The following article will elaborate on types of volcano based on their activity and shape.
Some of the examples of active volcanos are
Mount Vesuvius in Italy, Mount Fuji in Japan, Mauna Loa in Hawaii Island, etc.
Characteristics of Volcanoes
1. Volcanoes are usually conical in shape.
2. These have one or more crater.
3. Volcanoes may include lava, rock fragments, ash, and gas.
4. The lava accumulates on the surface and clumps up. And volcanoes are created.
5. On top of the volcanoes has crater.
6. The volcano contains one or more craters.
7. Lava emitted from the volcano can be both acidic and alkaline.
How Many Active Major Volcanoes Are There In World?
There are about 1,500 potentially active volcanoes worldwide, excluding continuous belts of volcanoes under the sea at dispersal centers such as the Mid-Atlantic Ridge. Of these, the major volcano number is about 356. Of these 1,500 volcanoes, about 500 have erupted in historical time.
Different types of volcano
The eruption is an endogenous process. This process results in the formation of volcanoes. These volcanoes are divided into several classes.
Types of volcano according to the structure and shape
The volcanoes are divided into four parts according to the shape and structure. These four types of volcano are as follows
1. Composite Volcano
Most of the volcanoes are of this type. Such volcanoes are formed by combining small and large eruptions over a long period. As a result of eruptions, the volcanic material is stored around the pores. Then the flow of lava falls on it. In this way, the volcanic altitude gradually increases as a result of many eruptions, and different layers can be seen. This is why this volcano is often called Strato Volcano (1).
Fig: Composite Volcano
Characteristics of Composite volcano
1. This type of volcanic cone slope is equal and steep.
2. It has many layers.
3. Caldera is created in this type of volcano.
Example of Composite volcano
Mount Fuji in Japan
2. Cinder Cones Volcano
Such types of volcanos are formed by the deposition of pyroclasts around the cracks or holes in the surface.
Fig: Cinder Cones Volcano
Characteristics of Cinder Cones Volcano
1. This volcano is much cone-shaped.
2. The cone is low altitude and the cone slope does not exceed 30° to 40°.
3. Pyroclast is deposited around the cracks or holes in the surface of the volcano. This, in turn, increases the height of the volcano.
Example of Cinder Cones Volcano
Monte Nuevo in Italy
3. Shield Volcano
Liquid lava comes out slowly without any explosion in the surface hole. And around the hole, the lava extends far and wide. And this kind of volcano is created.
Fig: Shield Volcano
Characteristics of Shield Volcano
1. According to the nature of lava, these volcanos are two types. The volcano formed in acidic lava is dome-shaped whereas volcano formed in alkaline lava is flattened. Its slope (10°) is very low.
2. This type of volcano is created without exploding in the hole of the surface.
Example of Shield Volcano
Mauna Loa in Hawaii
4. Explosion Vent or Pit Volcano
The explosion creates a hole on the surface. The lava is stored around the holes. And low create volcano is formed. This is called Explosion vent or pit volcano.
Fig: Explosion Vent or Pit Volcano
Characteristics of Explosion vent or pit volcano
1. The eruption caused a hole in this volcano.
2. The low crater ring is formed in this volcano.
3. This volcano has a very low altitude.
4. There are volcanic lakes is formed in the crater of the volcano.
Example of Explosion vent or pit volcano
Krakatoa in Indonesia
Types of Volcano according to the continuation or activation
The volcanoes are divided into three types according to their continuation or activation. Therefore different types of volcano are as follows
1. Active Volcano
The volcano that still erupts is called Active Volcano. There are two types of Active Volcano. These are Incessant Volcano and Intermittent Volcano.
a. Incessant Volcano
Such kind of active volcanos constantly emits lava and gases. An example is Vesuvius in Italy.
b. Intermittent Volcano
From this volcano, there are occasional eruptions. An example is Stromboli in Italy.
2. Dormant Volcano
This volcano is currently inactive. But there is a possibility of an eruption from this volcano in the future. An example is Mount Fuji in Japan.
3. Extinct Volcano
These volcanos are inactive volcano. Scientists have confirmed that eruption is never possible from this volcano. One such example of an extinct volcano is Mount Popo in Myanmar.
How many active volcanoes on Hawaii Island?
Hawaiian Island is made up of a hot spot of magma located beneath the surface of the earth throughout history. The magma is bubbling and forms on its own until it is tall enough to break the surface of the ocean and form the island. As the Pacific tectonic plate moves slowly, a new island begins to form beneath the ocean floor behind the ends. An active volcano is one that has caused at least one explosion in the last 10,000 years. If the volcano is not active and its last eruption occurred more than 10,000 years ago, it is defined as extinct.
The five main volcanoes in Hawaii are considered active. Four of these active volcanoes are located on the big island. These include Kilauea, Mauna Loa, Mauna Kea, and Hualalai. The other is located on Maui and it is Haleakala Mountain. There is also a sixth active volcano called Loihi, which is still submerged underwater on the shores of the big island near Kilauea.
Kilauea is one of the world’s most active volcano. It is located on the Big Island. This volcano has huge eruptions during the spring of 2018.
2. Mauna Loa
Mauna Loa has exploded 15 times in the last 120 years on the Big Island. Scientists say that this volcano is due to eruptions. As a total mass, it is the largest volcano in the world but it is not the longest volcano.
3. Mauna Kea
Mauna Kea is the longest volcano in the world when measured from the bottom of the ocean to the Big Island. It is currently dormant, but in the future, scientists believe it will erupt again. This volcano was last spread over 4,000 years ago.
Hualalai has erupted in 1801 but it has had other rumblings since that last eruption on Big Island. During 1920, the magma movement between volcanoes caused great earthquakes. The volcano has been closely monitored since 1980 and since then there has been no earthquake but it is still considered an active volcano.
Haleakala has not exploded since the 17th century but is still considered active. This popular volcano is located in Maui. Scientists believed that a future explosion should be expected but they are not seeing any signs of it happening any time soon.
Loihi is Hawaii’s other active volcano. But it is not very well known yet. At this time it is still submerged under sea level off the Shore of Big Island but it is currently erupting underwater.
Written By: Manisha Bharati