Notes on Natural Disasters

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  • Topic: Volcano, Volcanology, Magma
  • Pages : 12 (2856 words )
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  • Published : February 3, 2013
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Energy Source of Natural Hazards
Disasters occur where and when the earth’s natural processes concentrate energy and then release it, killing and causing destruction.

Four energy sources make the earth an active body: 1) the Earth’s internal energy; 2) solar energy; 3)gravity; 4)the impact of extraterrestrial bodies The interior of the Earth holds a tremendous store of heat released primarily from the ongoing decay of radioactive elements. Earth’s internal energy flows unceasingly toward the surface. * Over short time span: released as eruptions from volcanoes and by earthquakes. * Over long intervals of geological time, the flow of internal energy has produced continents, oceans and atmosphere. * On a planetary scale, this outward flow of internal energy causes continents to drift and collide, constructing mountain ranges and elevated plateaus. Gravity is an attractive force between bodies. The relatively great mass of the earth has powerful effects on smaller masses such as ice and rock, causing snow avalanches and landslides. Hydrological Cycle: about a quarter of the sun’s energy that reaches the Earth evaporated and lifts water into the atmosphere, creating the hydrological cycle. At the same time, constant gravity bring atmospheric moisture down as snow and rain. * On short timescales, unequal heating of the oceans and atmosphere at the Earth’s pole vs the equator created density differences in water and air that are acted on by gravity to create weather like storms, strong winds and ocean waves. * On a long timescale, the sun and gravity power the agents of erosion—glaciers, streams, underground waters, winds, ocean waves and currents that wear away the continents and dump their broken pieces and dissolved the remains into the sea. Asteroids and comets: impact the earth .

* Origin of the Sun and Planets
* Solar system formed by growth of the Sun and planets through collisions of matter within a rotating cloud of gas and dust. *
* Solar System grew as a rotating spherical cloud of gas, ice, dust and other solid debris known as the solar nebula gravity within the cloud attracted the particles together and grew in size-> resulting in greater gravitational attraction to nearby particles and thus more collisions matter drew inward and size of cloud decreasesspeed of rotation increases and the mass began flattening into a disk greater accumulation of matter at the centre resulted the sun The two main constituents of the Sun are the lightweight elements H and He Nuclear fusion began at very high temperature

Solar radiation: H combine to form He with some mass converted to energy. The inner planets

Volcanoes Learning Goals10/11/12 11:51 PM

Lecture 1

1. Identify key properties (density, viscosity, silica content, & temperature) of different types of magma. Density: water<magma<crust and mantle, so magma sinks in water but rises from crust and mantle. Viscosity: it controls flow and eruption style, depends on temp, gas and crystal content. SiO2 content: Felsic —light color, high V, sticky, Granite, Rhyolite. Mafic —dark color, low V, runny, Basalt, Gabbro Temperature: 600-1200,

Hot magma: low V, low silica
Cool magma: High V, high silica
Gas content: Volities, begins with 10% gas dissolved.
Gas content decreases V and decrease density.
Magma riseslower Pless solubilitybubbles

2. Explain why magma erupts or not
Magma, created by melting pre-existing rock below the Earth’s surface, reached surfaces through fractures and extrudes as lava or explodes as pyroclastic material. (Below the Earth’s surface) Lava is melted rock exposed at the Earth’s surface.

It goes through source, transport (dikes and sills), storage and eruption region during an eruption.

3. Describe the different types of eruptions and how they are related to magma properties *
4. List the different...
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