LESSON-1.4-ES-Semis.pptxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

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1. MAGMA AND VOLCANISM LESSON 1.3

2. EARTH’S INTERNAL HEAT Essential in sustaining life on Earth as it drives most geological processes including volcanism and plate tectonics. The source of this heat is attributed to leftover heat from its formation around 4.54 Ga as gravitational energy caused particles to accrete and collide with one another, forming large bodies. It includes the collision of Earth with Theia, which led to the formation of the moon and a differentiated earth.

3. EARTH’S INTERNAL HEAT Another source of earth’s internal heat is the disintegration of natural radioactive elements inside earth such as the radioactive decay of U, Th, and K.

4. Magma Molten rocks found beneath the Earth’s surface. Less dense than surrounding solid rock, and capable of rising to the surface. When magma emerges to the surface, it is called as LAVA. Usually composed of abundant elements including silicon, aluminum, iron, calcium, magnesium, sodium, potassium, hydrogen, and oxygen.

5. PROPERTIES OF MAGMA Most common component is silica. It has very high temperature The melting temperature of rocks could range from 800 degrees Celsius to 1400 degrees Celsius. Has the ability to flow

6. VISCOSITY The degree of resistance to flow The more viscous a substance is, the less fluid it becomes. Magmas with high silica are more viscous than low silica magmas. Gas content is higher in magma when the temperature is higher and this makes the magma less viscous.

7. VISCOSITY Lava that just came out of a volcano has very high temperature and flows readily; but as temperature decreases, it becomes more viscous and eventually stops flowing.

8. FORMATION OF MAGMA Magmas are formed when conditions are right to cause preexisting solid rocks to melt. The common notion that that the crust floats over a sea of molten rock is WRONG because the mantle is mostly solid.

9. WAYS HOW MAGMA CAN BE GENERATED Decompression melting Flux melting Heat transfer melting

10. VOLCANOES Visible manifestations of the process of rock formation. It is a vent that serves as conduit of lava or molten rock that reaches the Earth’s surface.

11. CRATER The funnel shaped depression where materials are ejected.

12. ERUPTION The event when the lava is spewed out of the volcano.

13. 2 TYPES OF ERUPTIONS Effusive Explosive

14. EFFUSIVE ERUPTION Dominated by the flow of lava and formation of fountains and lakes.

15. EXPLOSIVE ERRUPTION Ejects ash and larger fragments of pyroclastic materials, forming ash clouds that eventually collapse and cover the slopes of volcano.

16. EXPLOSIVE ERRUPTION Ejects ash and larger fragments of pyroclastic materials, forming ash clouds that eventually collapse and cover the slopes of volcano.

17. THREE DIFFERENT KINDS OF VOLCANOES ACCORDING TO ITS SHAPE Shield Volcano Stratovolcanoes or composite volcanoes. Cinder cone

18. SHIELD VOLCANO Forms a very broad dome with a gentle slope that covers a very wide area. Mostly made of alternating layers of basaltic lava and cinder accumulation. (Cinders are granular formed by lava fountains.) Examples are volcanoes in Hawaii.

19. SHIELD VOLCANO

20. STRATOVOLCANOES OR COMPOSITE VOLCANOES Composed of alternating layers of lava and pyroclastic materials. Composed of intermediate to felsic rocks and they tend to build large and high volcanic edifice. Examples are Mayon Volcano, and Mount Pinatubo.

21. STRATOVOLCANOES OR COMPOSITE VOLCANOES

22. CINDER CONE Consists of small cone formed by spattering of lava. Composed of cinder with mafic Composition. Examples are Binintiang Malaki located within Taal Volcano and Smith Volcano in Babuyan Island.

23. CINDER CONE

24. VARIOUS TYPES OF MATERIALS FORMED DURING VOLCANO ERUPTIONS Pahoehoe Obsidian Pumice Pyroclastic Debris Lapili Volcanic Ash Tuff Bombs

25. VARIOUS TYPES OF MATERIALS FORMED DURING VOLCANO ERUPTIONS Blocks Pyroclastic flow deposit Ignimbrite Lahar

26. VARIOUS TYPES OF MATERIALS FORMED DURING VOLCANO ERUPTIONS 1. Pahoehoe – lava with smooth surface. But those with very rough surface are called aa. 2. Obsidian – Pure volcanic gas. 3. Pumice – made of volcanic gas but with a frothy texture characterized by lots of open spaces caused by gas bubbles. 4. Pyroclastic Debris – fragmental materials of various grain size produced by a volcano.

27. VARIOUS TYPES OF MATERIALS FORMED DURING VOLCANO ERUPTIONS 5. Lapili – pea to marble sized fragments of lava 6. Volcanic ash – very fine particles composed of glass shards, crystals, and fragments of existing rocks. 7. Tuff – lithified volcanic ash 8. Bombs – Blobs of lava that are thrown into the air and develop a streamlined and smooth shape fragments.

28. VARIOUS TYPES OF MATERIALS FORMED DURING VOLCANO ERUPTIONS 9. Blocks – larger nonstreamlined chuncks of lava or preexisting rocks. 10. pyroclastic flow deposit – aggregate of pyroclastic debris that flows on the slope of volcano. 11. Ignimbrite – pyroclastic deposit that is dominantly composed of pumice. 12. lahar – pyroclastic debris mix with water.