Geological Catastrophes Midterm Review

Geological Catastrophes Midterm Review - Geological...

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Unformatted text preview: Geological Catastrophes Review 23:14 The layering of the Earth is characterized by: • Differences in density o Less dense materials are on top of more dense materials o Crust overlies mantle • By differences in strength o Lithosphere overlies asthenosphere—lithosphere is rigid (solid rock) as opposed to the asthenosphere which is fluid like (plastic rock) and then mesosphere is solid mantle below asthenosphere o Mesosphere asthenosphere lithosphere hydrosphere atmosphere • Center of Earth: Iron-rich core ~7,000 km in diameter o Inner core is solid and 2,450 km in diameter o Outer core is liquid and has viscous convection currents, responsible for Earth’s magnetic field • Surrounding core is Earth’s mantle, 2,900 km thick o Stony in composition (like chondritic meteorites) o 83% of Earth’s volume, 67% of Earth’s mass • Low-density elements have been ‘sweated’ out of the mantle to form the crust, atmosphere and oceans Earth’s history: • Earth is 4.6 billion years old • Earth began as aggregating mass of gases and particles • Processes of planet formation created huge amounts of heat o Impact energy o Decay of radioactive elements o Gravitational collapse energy o Differentiation into layers: As temperature rose above 1,000 centigrade, iron melted Liquid iron is denser than remaining rock, so sank toward center of Earth and formed inner and outer core Release of gravitational energy produced more heat—remaining rock melted, allowing low-density material to rise Low-density material formed crust, oceans, and atmosphere • 3.9 billion years ago: large oceans, small continents • 3.5 billion years ago: life (photosynthetic bacteria) • 2.5 billion years ago: large continents • 1.5 billion years ago: plate tectonics Where does energy to drive catastrophes originate? • Impacts of extraterrestrial objects (meteors/comets) • Gravitation—both internal (collapse) and external (tides) • Earth’s internal heat— latent heat from formation and radioactive decay • Solar radiation World Disaster Fatalities: • There are more people killed in poorer nations then in industrial countries • amount of people killed in natural disasters in increasing order—industrial nations developing nations poorest nations 2009- Was the mildest year for natural disasters!!! World Disaster Damage ($$$): • Natural disasters cost industrial nations more money than poorer countries o Amt. of money caused by natural disasters in increasing order for each type of society—poorest nations developing nations industrial nations The number of earthquakes is NOT increasing, the Population IS!!!The number of earthquakes is NOT increasing, the Population IS!...
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This note was uploaded on 08/26/2011 for the course EARTH 20 taught by Professor Staff during the Spring '11 term at UCSB.

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Geological Catastrophes Midterm Review - Geological...

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