Geog Exam 3

4 major layers that form the Earth’s internal structure

Crust, mantle (upper and lower, Liquid inner core, solid outter core

What is the crust made up of?

Oceanic crust - thinner made of denser rocks

Continental crust - thicker - less dense rocks

DENSITY INCREASES w/ DEPTH

THICKNESS NOT EVENLY DISTRIBUTED

Difference between upper and lower mantle

Lower mantle = lies above outer core - plastic solid molten rocks

* below asthenosphere rocks are hot but ridgid under pressure
* 1400 miles thick
* seismic wave indicate currently in solid state composition

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Upper mantle = between crust and lower mantle

* less thick than lower mantle
* Seismic wave indicates less dense than lower mantle

What is the asthenosphere?

it is the mantle zone where rocks are plastic and can be easily deformed

Difference between the liquid inner core and solid outer core

* inner = liquid
* 1400 miles thick
* surface = 1800 below SL 1/2 to center of plant
* inner and outer = 12g/cm3 density
* outer = solid
* 760 miles radius
* 3200 miles surface
* iron and nickel composition
* enormous pressure for solid state - ex temperature

who discovered density of the earth’s materials?

Mohorovicic = MOHO discontinuity: narrow zone of change in mineral composition base of the crust via evidence seismic waves

Shaper density contrast between upper and lower mantle = upper is much denser

Difference between oceanic and continental crusts

Oceanic: formed by high density - MAFIA dark colored rocks aka basalt

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Continental: formed by low density - FELSIC light colored rocks aka granite

Explain the three types of tectonic plate movements

Convergence, Divergence and Transformation

Tectonic plate movement Convergence..

Oceanic - Continental = lighter less dense continental crust forces the heavier denser crust to sink = subdiction (intense tectonic activity) = melting rocks = fissures = volcanism

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Oceanic - Oceanic = oceanic plate collides w/another despite density = one subduction = new landforms of volcanic island = japan island and aleutian island

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Contient- Contient = continental plates collide with another but no subduction = collision = compression and thickening = greatest mountain ranges - himalayas

Tectonic plate movements .. divergence..

move away from each other = plates can diverge from each other

* continent rift valley - fault produces a valley EAST AFRICA RIFT VALLEY

Plate tectonics movements .. transform

move along each other - causes EQ, does not produce topography- no creation or destroy of crust = MAJOR SEISMIC ACTIVITY famous transformational boundary = san andreas fault

* gulf of california west of the faulty = pacific plate
* Areas east of the fault = North american Plate

What is the continental drift?

All the continents were originally connected to each other

mid oceanic ridges and mountain ranges on the ocean floor

* age of the oceanic crust = younger rocks near the ridges and older farther away from the ridges
* Mid oceanic ridge = molden material flows from the mantle upward and solidifies at the surface
* Seafloor spreading = as the new rocks forms pushed older rocks further away from the ridge & WIDENS the ocean

What are earthquakes?

* come from seismic activity
* When plates move against each other = tension
* tension released - an earthquake
* happens in the lithosphere = makes ground shake
* majority of EQ near tectonic plate boundaries fous is usually within the lithospheres epicenter

Differentiate between focus and epicenter 

Focus: location where earthquakes originate = lithosphere

Epicenter: point directly above the focus on the surface of the earth

How can an earthquake be measured?

Seismograph: instrument to detect and record seismic waves

Seismogram: records the ground motion results from the S.graph

* 3 waves
* P primary pressure - fastest - 1st - back & forth - body
* S second. shear - 2nd - vibrate - right at angle - direct. of body
* Surface waves:
* Love waves - shake side to side more disructive
* Rayleigh waves - moves surface around in source and forward and back down (ocean water)

Difference between magnitude and intensity:

Mag. = measures the amount of energy that is released - based on AMPLITUDE - RICHTER SCALE - logarithmic defines magnitude based on amplitude of seismic waves & distance to the epicenter

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Intensity = measures the amount of shaking that occured, modified mercalli intensity scale - measures severity better than magnitude - 1-12 categories Based on human impacts and natural environment effects

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Pacific Ocean basin = ring of fire = largest earthquakes strongest earthquakes = subduction zone (continental-oceanic or oceanic-oceanic plates)