Volcanoes (Parts, Types, Classification) | Grade 9 Science DepEd MELC Quarter 3 Module 1

[Music] hi there did you know that the tiny little island of vulcan point in the philippines is the world's largest island within a lake that is situated on an island located in a lake within an island vulcan point also happens to be one of the cones of the active taal volcano interesting piece of land indeed the philippines is known for its diverse natural resources and scenic views like mountains and volcanoes having these in the country is not surprising [Music] this is because the philippines is situated or is part of the pacific ring of fire which is characterized by frequent earthquakes and volcanic eruptions the philippines is located somewhere here this is not the actual location but this is just for representation purposes volcanism is a phenomenon connected with volcanoes and its volcanic activity a volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth volcanoes are openings or vents in the earth's crust where magma ash and gases escape that may cause violent and spectacular eruptions as pressure builds up in the mantle magma rises and pushes through vents and fissures it forces its way out which can lead to a volcanic eruption this hot liquid rock under the earth's surface is known as magma as pressure in the molten rock builds up it needs to escape somewhere so it forces its way up fissures or narrow cracks in the earth's crust once the magma erupts through the earth's surface it is called lava most volcanoes are formed as a result of geological activities along the plate boundaries in the ring of fire volcanoes are formed in the subduction zone when two plates collide one plate sinks into the mantle and melts the resulting magma rises through the other plate above it and forms a chain of volcanoes these are volcanoes from melted crusts or volcanoes from subduction mount fuji is a product of the subduction zone that straddles japan with the pacific plate to the north and the philippine plate to the south subducting underneath the eurasian plate some volcanoes are also formed along the rift of two plates which are being pulled apart magma rises out of the rift from the sea floor as the sea floor spreads these are called underwater volcanoes iceland is formed by the coincidence of the spreading boundary of the north american in eurasian plates and a hot spot are mantleplum an upsurge of abnormally hot rock in the earth's mantle as the plates move apart excessive eruptions of lava constructed volcanoes and filled rift valleys some volcanoes are formed at the center of a plate by plumes it is a rising column of super hot magma from some places in the mantle the shooting magma can burn a hole into the plate above and form a volcano these hot spots are found at a number of locations around the globe these are called hot spot volcanoes the hawaiian islands were formed by such a hot spot occurring in the middle of the pacific plate while the hot spot itself is fixed the plate is moving so as the plate moved over the hot spot the string of islands that make up the hawaiian island chain were formed let's label each part of the volcano we already know magma which is the molten rock beneath the earth's surface then we have the magma chamber this is where magma is formed next the parasitic cone this is a small cone-shaped volcano formed by an accumulation of volcanic debris the sill is a flat piece of rock formed when magma hardens in a crack in a volcano a vent is an opening in the earth's surface through which volcanic materials escape the crater is the mouth of a volcano it surrounds a volcanic vent a laccliff is a sheet-like intrusion that has been injected within or between layers of sedimentary rock the layers of ash are fragments of lava or rock smaller than two millimeters in size that are blasted into the air by volcanic explosions and finally the ash cloud it is a cloud of ash formed by volcanic explosions volcanoes have several shapes which are controlled by the composition of the magma and therefore the nature of its eruption geologists generally group volcanoes into four types cinder cone composite shield and lava dome volcanoes a cinder cone volcano is also known as korea cone volcano it forms when volcanic cinder or blobs of congealed lava of basaltic composition comes out from one vent its explosive eruptions are caused by gas rapidly expanding and escaping from the molten lava that comes out sort of like a fountain the lava cools quickly and falls a cinder's buildup around the vent form a round shape leaving a crater at the summit these volcanoes will be as high as 100 to 400 meters because the lava is blown violently into the atmosphere it breaks small fragments then solidifies and falls as cinders that surround the vent [Music] an example is the taal volcano in the philippines and perikutan in mexico a composite volcano is also known as a stratovolcano it includes a number of the world's grandest mountains it is composed of an alternating layer of lava flow which justifies the name composite volcano it can have a cluster of vents with lava breaking through walls or issuing from fissures in the perimeters of the mountain the eruptions are extremely explosive and dangerous pressure builds within the magma chamber as gases under immense heat and pressure are dissolved within the magma when the magma reaches the vents the pressure is released and the gases explode violently these volcanoes are up to 100 to 3500 meters high mount fuji in japan and mount mayon in the philippines are examples of composite volcanoes shield volcanoes are huge gently sloped volcanoes that exclusively erupt basaltic lava these include a number of the biggest volcanoes within the world it is built by many layers of low viscous lava flows the eruptions don't seem to be explosive the lava oozes out from the central vent or a gaggle event and spreads far building a dome-shaped profile similar to a warrior shield they are as high as 9000 meters from the bottom [Music] the volcanoes within the hawaiian island including kilauea and diamond head are shield volcanoes a lava dome is also referred to as volcanic dome these are relatively small circular mounds formed because the lava is simply too viscous to flow which makes it pile over and around the vents because the lava oozes out its outer surface cools and hardens then shatters spilling loose fragments down its side lava domes are found within the crater or in the edges of enormous composite volcanoes their height depends on the dimensions of the composite volcanoes around them there are lava domes within the crater of chaitan lava dome in chile and lassen peak in western united states the philippines has more than 100 volcanoes as of 2013. there are several ways by which volcanoes can be classified the philippine institute of volcanology and seismology or fevox for short have adapted a system where the philippine volcanoes can be classified as active erupting active torment or inactive an active volcano is a volcano that has had at least one eruption during the past 10 000 years an active volcano might be erupting or dormant an erupting volcano is an active volcano that is having an eruption [Music] a dormant volcano is an active volcano that is not erupting but is supposed to erupt again there are 24 active volcanoes in the country according to box the majority of the active volcanoes are located in the island of luzon an inactive volcano is one that could erupt but has not erupted for more than ten thousand years inactive volcanoes are also called extinct or sleeping volcanoes inactive volcanoes are expected to erupt again at some point despite being dormant for thousands of years volcanoes with no record of eruptions are considered as extinct or inactive their physical form since their last activity has been altered by agents of weathering and erosion with the formation of deep and long gullies activity does not necessarily indicate the volcano will not erupt again but what are the advantages and disadvantages of living near volcanoes volcanoes and volcanic activities are usually related to destruction risk of living near volcanic areas include destruction to land by volcanic materials landslides pollution and effects on weather however these materials are important to human life as an example lava and volcanic ash contain nutrients that enrich the soil many volcanic materials are very useful in industrial and chemical uses and as a source of heat energy these beautiful and magnificent landforms also attract the attention of tourists so people living near these volcanoes make a living from it now let's wrap things up volcanism is a phenomenon connected with volcanoes and its volcanic activity such as the movement of magma from the mantle to the surface of the earth a volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth hot liquid rock under the earth's surface is known as magma once the magma erupts through the earth's surface it is called lava volcanoes may form from melted crust or subduction as underwater volcanoes or as hot spot volcanoes there are four types of volcanoes according to shape namely cinder cone composite shield and lava dome volcano fevols classifies volcanoes as active erupting active dormant or inactive volcanoes that's all for now we will be discussing about volcanic eruption in our next video so stay tuned see you on our next video and don't forget to keep your minds busy you like this video please subscribe to our channel and hit the notification icon for more videos like this

Channel: The Learning Bees

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Keywords: The Learning Bees, Department of Education, DepEd, MELC-Based, Most Essential Learning Competencies, Science, MELC, Grade 9, Earth science, Volcanism, Pacific Ring of Fire, Taal Volcano Facts, Volcano, Volcanic eruption, What's the difference between magma and lava, How are volcanoes formed, Volcano formation, Parts of a Volcano, Types of volcano, Philippine Institute of Volcanology and Seismology, PHIVOLCS, Volcano classification, advantages and disadvantages of living near volcanoes

Id: PoHfjq6n-Po

Length: 12min 47sec (767 seconds)

Published: Sun Mar 21 2021