Volcanic Eruption | Grade 9 Science DepEd MELC Quarter 3 Module 2

[Music] hi there in our previous lesson we discuss about the parts and types of volcanoes in this video we will talk about the process of volcanic eruption if you still haven't watched the previous lesson you can pause this video and watch that one first to better understand or lessen today so let's get started magma is a semi-liquid rock crystallized minerals dissolved gases and extremely hot liquid formed and found beneath the surface of the earth much of the earth's mantle is made largely of magma this magma can push through holes or cracks in the crust causing volcanic eruptions when magma is ejected out of the volcano it is called lava when it cools in solidifies it is known as igneous rocks the temperature of magma ranges from 700 to 1300 degrees celsius so what determines the nature of volcanic eruption the primary factors affecting volcanic eruption are the magma's temperature its chemical composition and the amount of dissolved gases it contains these factors can affect the magma's viscosity in different ways viscosity is the property of the material's resistance to flow it is also described as the liquid's thickness and stickiness the more viscous and thicker the material is the greater is its resistance to flow let us discuss how each factor affects the viscosity of magma first let's look at how the temperature of magma affects its viscosity the viscosity of magma decreases with temperature the higher the temperature of magma is the lower is its viscosity as lava flows it cools and begins to harden its ability to flow decreases and eventually it stops next let's look at how the composition of magma affects its viscosity magmas with high silica content are more viscous than those with low silica content the magma that contains less silica is relatively fluid and travels far before solidifying lastly the amount of gases contained in the magma affects its viscosity gas mainly water vapor dissolved in magma tends to increase its ability to flow therefore in near-surface environments the loss of gases make magma more viscous forming a dome or a columnar [Music] magma inside a volcano has a high temperature as the magma is continuously heated it goes up as it rises gas bubbles are developed the gas bubbles are trapped and they expand causing the molten material to swell and resulting in a gradual increase in pressure within the volcano when the pressure exceeds the strength of the overlying rock fracturing occurs the resulting breaks lead to a further drop in confining pressure which in turn causes even more gas bubbles to form magma is then ejected out as lava each volcano erupts differently multiple types of eruptions can occur at each volcano the eruption type can vary minute to minute the style of eruption depends on a number of factors including the magma chemistry and content temperature viscosity volume how much water and gas it contains the presence of groundwater and the plumbing of the volcano the icelandic type is characterized by effusions of molten basaltic lava that flow from long parallel fissures such outpourings often build lava plateaus the hawaiian type is similar to the icelandic variety in this case however fluid lava flows from a volcano summit and radial fissures to form shield volcanoes which are quite large and have gentle slopes somalian eruptions involve moderate bursts of expanding gases that eject clots of incandescent lava in cyclical or nearly continuous small eruptions because of such small frequent outbursts stromboli volcano located on stromboli island off the northeast coast of italy has been called the lighthouse of the mediterranean the volcanion type named after volcano island near stromboli generally involves moderate explosions of gas laden with volcanic ash this mixture forms dark turbulent eruption clouds that rapidly ascend and expand in convoluted shapes a palliant eruption is associated with explosive outbursts that generate pyroclastic flows dense mixtures of hot volcanic fragments and gas the fluidized slurries produced by these eruptions are heavier than air but are of low viscosity and pour down valleys and slopes at great velocities as a result they are extremely destructive the plinian type is an intensely violent kind of volcanic eruption exemplified by the outbursts of mount vesuvius in italy in this type of eruption gases boiling out of gas-rich magma generate enormous and nearly continuous jetting blasts that core out the magma conduit and rip it apart the uprushing gases and volcanic fragments resemble a gigantic rocket blast directed vertically upward plinian eruption clouds can rise into the stratosphere and are sometimes continuously produced for several hours lightning strikes caused by a buildup of static electricity are common and close to plinian ash clouds adding one more element of terror to the eruption volcanoes emit different substances here's a rundown of all of these volcanic bombs are molten rocks that are thrown out from a volcano and are at least six to six in size an eruption cloud are ash falls that are like powdery snow but it's snow that won't melt these blankets of ash suffocate plants and animals the eruption cloud can extend up to 12 miles above a volcano then it can reach thousands of kilometers in distance raining ash over regions if magma is thick and sticky gases cannot escape easily pressure builds up until the gases escape violently and explode this type of magma blasts up into the air and breaks apart into pieces called tephra tephra can range in size from tiny particles of ash to house size boulders tephra destroys everything in its path an eruption column are clouds of heated ash in tephra that are released from a vent during an explosive volcanic eruption a pyroclastic flow contains fast-moving volcanic matter and hot gas it moves away from a volcano and incorporates tefra when hot volcanic material mixes with water from streams or snow and ice lahar mudflows form magma that erupts is called lava lava flows are molten rock that ooze to the earth's surface after a volcanic eruption so how do volcanic eruptions affect society a volcanic eruption is often associated with both positive and negative effects our planet the earth is active and as such it undergoes a process of constant renewal by way of volcanic eruptions volcanic eruptions help bring out various minerals and chemicals to the surface this process helps to increase the fertility of the soil which is why volcanic soil is of much value volcanoes can provide you with a ready source of power since the same can be tapped by geothermal power stations and help to power up the various cities located close by volcanoes have been spewing moisture-laden gases directly into the atmosphere for almost 4 billion years and more volcanic ash is valued as a premium building and construction material all volcanic eruptions result in widespread damage to the point that whole cities are destroyed along with the entire local infrastructure this can impact the local population on several levels and it can't take a while before the city can be reconstructed it can cause loss of lives and properties even though a volcanic eruption leads to increased fertility in the soil the process takes time meanwhile the fallout in a local environment is immediate with ash and toxic gases all of which impact the local flora and fauna [Music] now let's wrap things up the primary factors affecting volcanic eruption are the magma's temperature its chemical composition and the amount of dissolved gases it contains viscosity is the property of the material's resistance to flow the type of eruption depends on a number of factors including the magma chemistry and content temperature viscosity volume how much water and gas it contains the presence of groundwater and the plumbing of the volcano there are six types of volcanic eruptions namely icelandic hawaiian strombolian vulcanian paleon and plinion that's all for now we will be discussing about how energy from volcanoes may be tapped for human use in our next video so stay tuned see you on our next video and don't forget to keep your minds busy if you like this video please subscribe to our channel and hit the notification icon for more videos like this

Channel: The Learning Bees

Views: 59,045

Keywords: The Learning Bees, Department of Education, DepEd, MELC-Based, Most Essential Learning Competencies, Science, MELC, Grade 9, Earth science, what happens when volcanoes erupt, volcanic eruption, volcanic emissions, difference of magma and lava, factors affecting volcanic eruption, types of volcanic eruptions, Icelandic, Hawaiian, Strombolian, Vulcanian, Pelean, Plinian, How do volcanic eruptions affect society, advantages and disadvantages of volcanic eruption, tephra, pyroclastic flow, lahar

Id: JTdiPzJUdng

Length: 11min 25sec (685 seconds)

Published: Mon Mar 29 2021