Menu

Search results for «volcano»

Global distribution of volcanoes

There are about 800 active volcanoes on the earth’s surface. Besides these these, there are many thousands of extinct volcanic cones, most of which are under the seafloor. A great majority of volcanoes are found to be concentrated along the following belts. Read Similar article The Circum-Pacific Belt The Alpine-Indonesian Belt The Mid-Oceanic Ridges African …

Volcanoes and their types

A volcano is a vent or fissure in the earth’s crust through which hot lava and volcanic gases are thrown out. Volcanic eruptions may be either explosive or quiet. The earth’s upper mantle (asthenosphere), under the crust, is nearly molten. Magma originates at this depth. They migrate upwards, often along faults. In a volcano, the …

Active, dormant and Extinct Volcanoes

Active Volcanoes: An active volcano may be defined as the one which is definitely known to have erupted periodically in historic times. Kilauea volcano on Hawaii is the world’s most active volcano, followed by Etna in Italy and Piton de la Fournaise on La Réunion island. Further ordering the value of the activity of volcanoes …

Global distribution of Volcanoes

According to improved knowledge of ocean floor, topography, and geology the entire Pacific Ocean floor constitutes a very large tectonic plate with smaller Cocos and Juan de Fuca Plates. Most of the global volcanic activity is concentrated at convergent plate boundaries. The majority of the world’s active volcanoes lie along the Pacific Ring of Fire. …

What are Calderas (Volcano)?

The empty chamber of a volcano formed after the completion of the eruption is known as the Caldera. As the eruption of the volcano comes to an end, the vent and crater remain as a hollow shaped cavity. According to H.J de Blij, “A volcano‘s lava and pyroclastics come from a subterranean magma chamber, a …

What is a vent of volcano

It is also known as a fissure vent, eruption vent, or simply volcanic vent. A vent is a vertical pipe-like hole through which the volcanic materials/ lava (magma, rocks, debris, volcanic ash, water, and other fluids, and minerals) are extruded.

Volcano and its types

A volcano is a vent in the Earth’s surface, which allows the interior molten magma to erupt out due to extreme pressure and convection. The magma when it comes out of the interior of the earth is known as lava. The lava is composed of solid and molten rocks, debris, and gases, and fluid of …

Solar System

Solar System The Earth is a planet. It is a member of the solar system. Nine planets and the sun are the main bodies of the ”Solar System”. The planets in the order of increasing distance from the sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Each planet moves around the …

Introduction to Geology

Geology is a Science, which is devoted to the study of the Earth. It deals with all the features of the earth’s surface, its origin, composition, structure, history, inhabitants, and processes of change in its features. An important part of geology is the study of how Earth’s materials, structures, processes, and organisms have changed over time.

Composition of Lava

Composition The composition of almost all lava of the Earth’s crust is dominated by silicate minerals: mostly feldspars, feldspathoids, olivine, pyroxenes, amphiboles, micas and quartz. Rare nonsilicate lavas can form by local melting of nonsilicate mineral deposits or by separation of a magma into separate immiscible silicate and nonsilicate liquid phases. Silicate lavas Silicate lavas are molten mixtures dominated by oxygen and silicon, the Earth’s most abundant chemical elements, with smaller quantities of aluminium, calcium, magnesium, iron, sodium, …

Types of igneous rocks

There are two basic types of igneous rocks i.e. Intrusive Igneous rocks and Extrusive igneous rocks. Intrusive igneous rocks are those, which crystallize below the earth’s surface, and remain buried until the earth’s surface is eroded, while the extruded igneous rocks are those, which erupt onto the surface, where they cool quickly to form small …

Forms of Igneous Bodies

The igneous material is of two types; one is extrusive, and the other is intrusive. The extrusive igneous bodies are formed from the magma poured out at the surface of the earth. The lava flows are examples of extrusive igneous material. While the igneous bodies are formed by the consolidation of magma at some depth …

Chemical Composition of Igneous Rocks

Igneous rocks make approximately 90% of the earth’s crust by volume. But their great abundance is hidden on the earth’s surface by a relatively thin layer of sedimentary and metamorphic rocks. Igneous rocks are formed by the cooling and solidification of magma. Magma is a hot viscous, siliceous melt containing water vapour and gases. It …

What is Geology. Its main branches.

Geology is a Science which is devoted to the study of the Earth. It deals with all the features of earth’s surface, its origin, composition, structure, history, inhabitants and processes of change in its features. An important part of geology is the study of how Earth’s materials, structures, processes and organisms have changed over time. …

Landforms

Different types of rock give different and distinctive types of landform. For instance, limestones on weathering produce ”karst topography”. The landscape produced by the processes of weathering and erosion is closely related to climate and rock types. The angle of the surface slope is controlled directly by the strength of the rock. Hard rocks like …

Volcanic Activity and Plate tectonics

According to the plate tectonic theory, there are three principal zones of volcanic activities: (i) spreading centers, (ii) subduction zones, (iii) regions within the plates themselves. Let us first study the origin of magma and its relations to plate tectonics. Origin of Magma: Basaltic Magma: Most basaltic magma is believed to originate in partially molten …

Phenomena associated with volcanism

Volcanism is a natural phenomenon, according to which the interior hot material of earth’s asthenospher (one of earth’s layers, which forms upper mantle) is extruded out through a vent. Volcanism develops a couple of landforms. Apart from landform formation there are some other phenomena associated with volcanism. Hot springs, fumaroles, and sometimes geysers are found …

Volcanic Eruptions

Volcanic eruptions are of two types: (i) centeral eruptions, (ii) Fissure eruptions. Central Eruptions: In central eruptions, the emission of lava takes place through a vent. Such a volcano usually exhibits a cone-and-crater arrangement. This volcano may have parasitic cones on the flanks of the main structure. Etna, a European volcano, has more than 200 …

Global distribution of the Earthquakes

Earthquakes occur in geologically active areas, such as mid-oceanic ridges and mountain-building regions. The zones where earthquakes occur frequently are known as ”Seismic belts”. The principal seismic belts on the earth’s surface are as follow: Read more related articles Circum Pacific Belt: This belt encircles the Pacific ocean and more or less overlaps the belt …

Earthquakes

1. Introduction to an Earthquake An Earthquake may be defined as the shaking and trembling of the Earth’s surface caused by sudden releases of stress with the crust of Earth. Thus an earthquake releases the energy that has been gradually stored through the stress of increasing deformation of rocks. The released energy takes the form …