S3 IHE GE 2014/Chan ML

Transcription

1 S3 IHE GE 2014/Chan ML

2 Formation Types Advantages and Disadvantages of living near/in volcanic areas

3 Introduction Volcano, mountain or hill formed by the accumulation of materials erupted through one or more openings (called volcanic vents) in the earth's surface. They are usually found along diverging plate or constructive plate.

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5 Classification Active Frequently erupts Volcanoes along the Pacific Ring of Fire Mt. Etna, Mt. Merapi, Kilauea Dormant Has not erupted in recent times Can still erupt Mt. St Helens was considered dormant before 1980 it has not erupted since Mauna Kea Hawaii (last eruption: 2460 BC) Yellowstone Extinct Has not erupted in historic times Considered unlikely to erupt Kilimanjaro (Tanzania)

6 Lava Composition Silica Content- Amount of SiO2 that lava contains The higher the amount of SiO2 the more explosive the eruption Gas & Water Content-Amount of volatiles (C02, Water, Sulfur, etc) The higher the amount of volatiles dissolved in magma the more explosive the eruption Viscosity Measure of how easily material can flow; Low viscosity, lava flows easily; High viscosity, it does not flow easily; The more viscous the lava the more explosive the eruption

7 Type Basic Lava Shield volcano Acid Lava Composite volcano Production Constructive Plate Subduction Content Rich in iron and magnesium Rich in silica Temperature C C Type Fluid Viscous Movement Quickly Slowly Time taken to cool Cools, solidifies slowly Cools, solidifies quickly Distance Flows very far Does not flow far Eruption Quiet Violent Slope Gentle Slope Steep Slope Example Mauna Loa, Hawaii Mount Mayon, Philippines

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9 Structure

10 Formation Formed along diverging plate or constructive plate. Magma rises from the mantle through fractures due to the immense gas pressure in the magma chamber. Volcanic material spills or shoots out from the vent Cools and solidifies, piles up on the ground around the vent, forming a volcano. Volcanoes can also be formed through hot spots (Hawaii, Yellowstone)

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12 Types of Volcanoes: Shield Largest volcanoes on Earth Mauna Loa (Hawaii) Ash and Cinder Small cones usually in groups Paricutin (Mexico) Composite Explosive eruptions with pyroclastic materials Mt. St. Helens, Merapi, Vesuvius

13 Shield Broad, gentle slope Largest volcanoes on Earth Made of Fluid Basaltic lava Not explosive Common product of hotspot Mauna Loa (Hawaii) Ash and Cinder Small cones Made of ash and cinder: pyroclasts are thrown out and drop back around the vent Volcano grows rapidly, but not to great heights Paricutin (Mexico)

14 Composite Broad at the bottom and steep at the summit Made of viscous silica lava, Alternate layers of lava and pyroclastic material) Explosive eruptions with pyroclastic materials Mt. St. Helens, Merapi, Vesuvius Lahars (Indonesian word for mudflow) Lava + melted snow = Lahar (Pinatubo, Merapi and Nevado del Ruiz Mexico)

15 Shield Volcanoes Slightly domed shaped volcano Fluid basic lava Wide base Not explosive Little pyroclasts Example: a) Mauna Loa, Mauna Kea (hot spot volcanoes) b) Skaldbreidur (Icelandic volcano where the Mid-Atlantic ridge rises to sea level)

16 Hot Spots Rising columns of or plumes of magma that originate form a fixed position Magma plume melts a hole in the lithospheric plate Magma issues out from the vent As plates move, the volcano becomes extinct and anew volcano is formed The further the volcano is from the hot spot, the older it is. Developed by geophysicist J. Tuzzo Wilson, 1963

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18 Ash and Cinder Steep sided symmetrical volcano form from red-hot cinders and ash. Steep slopes and gentle base due to larger pyroclasts fall near the summit while the finer pyroclasts fall near the base Bowl-shaped summit crater Grows rapidly and found in groups Examples: Paricutin

19 Composite Mostly found in convergent plates, on continents and Island arcs Alternate layers of pyroclasts Steep slopes and gentle base due to larger pyroclasts fall near the summit while the finer pyroclasts fall near the base Acid lava solidifies in the central pipe build up tremendous pressure loud explosions Examples: Mt Merapi, Mt Mayon, Mt Fuji, Mt St Helens Also known as Strato Volcano

20 Eyjafjallajökull (pronounced AY-uh-full-ay-ho-kul) (Iceland 2010) Composite volcano Formed by the divergence of the mid-oceanic ridge: the N. Atlantic Plate and Eurasian Plate Published March 22, 2010 National Geographic News Ash and roughly thirty-story-tall lava fountains shoot from a half-mile-long (0.8-kilometer-long) rupture in the icy cap of southern Iceland's Eyjafjallajokull volcano early Sunday. Because volcanic ash can cripple jet engines, flights were not allowed in Icelandic airspace Sunday. As of Monday, air travel was gradually returning to normal, the Associated Press reported. The geology of Iceland, though, is anything but normal. The volcanic island lies just south of the Arctic Circle atop the Mid-Atlantic Ridge, where two tectonic plates are forever pulling apart. Magma from deep inside Earth rushes upward, filling the gaps and fueling Iceland's volcanic eruptions, which occur about once every five years.

21 Advantages and Disadvantages of living near / in volcanic areas

22 Advantages Economic Formation of fertile soil: lava and pyroclastic materials are weathered to form soil (farming: Gunung Merapi, Indonesia and Philippines) Formation of precious stones and minerals such as gold, silver, copper, zinc, lead and diamonds (Kimberley, South Africa) Tourism: hot springs (very popular in Korea and Japan), geysers, (Yellowstone National Park in USA) Geothermal energy that can use to generate electricity (Iceland) Making of roads using volcanic ash

23 Social Higher standard of living (infrastructure: transport, communication) Greater employment

24 Disadvantages Social Eruptions can disrupt daily activities Health problems (ash, gas) can irritate the lungs and eyes Destruction of properties Loss of lives Economic: Disruption of trade, tourism, huge amount of losses in the financial sector (Iceland s volcanic eruption on Europe) Cost in rebuilding Environmental Air/water/soil pollution

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26 Problems of Volcano Pollution due to pyroclastic materials, carbon dioxide and sulphur dioxide emitted out from volcano Tsunamis caused by explosions: Krakatoa (Indonesia) and Thera (Greece) Decline in temperature: ashes preventing incoming solar radiation

27 Videos (Health Hazards and Climatic Effects) ure=related (pyroclastic flow)