Geo Exam 2

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What is the intensity of an earthquake?

-measure of effects of an earthquake on people and buildings -shaking and damage -depends on EQ magnitude and population density, buildings, codes, ground materials, distance

Mountains and Volcanoes form at a convergent boundary when...

An oceanic plate subducts below a continental plate and the overriding plate gets pushed up.

If you find a plate boundary along the edge of an ocean next to a continent, what kind would it be?

Convergent

What kind of plate boundary do earthquakes normally occur?

Convergent

Which plate boundary creates the most dangerous volcanoes, largest earthquakes, and biggest mountains?

Convergent

What kind of plate boundary does subduction occur at?

Convergent plate boundary

Two situations in which a large-magnitude earthquake can have low intensity

If there is not a large population in the area or if the buildings are built on better ground material

Can earthquakes happen at all boundaries?

Yes but they are most common/largest at convergent

What is a mantle plume?

a circular column of magma that rises from deep within Earth

What is a Tsunami?

a giant wave created by vertical shift in ocean floor.

What is viscosity of magma?

a measure of materials resistance to flow

What are earthquakes?

a sudden slip on a fault, and the shaking caused by the split

At which type of tectonic setting would you expect the development of composite volcanoes?

an oceanic plate subducted beneath a continental plate

What is the intensity of an earthquake?

the measure of damage and deaths it caused.

What is peridotite?

the rock making up the mantle

What was Panthalassa?

the single ocean that existed after the Pangaean supercontinent formed

Melting occurs at a subduction zone primarily because...

it is at a mid-ocean ridge and experienced a change in pressure

What do we call mudflows produced by the melting of snow and glaciers on composite volcanoes?

lahars

Do silicrich (felsic) rocks melt at higher or lower temperatures than mafic rocks?

lower

At which type of tectonic setting would you expect the development of shield volcanoes?

mantle plumes

Where are most modern divergent plate boundaries found?

mid-ocean ridges

Which type of faulting is associated with the development of new ocean floor?

normal faulting

Where are continental volcanic arcs found?

on the overriding plate near a subduction zone

What are surface waves?

travel along earth's surface. They are the slowest

What are body waves?

travel through earth's interior. P(primary) waves are the fastest and S(secondary) waves are 2nd fastest

Earth's magnetic field switches polarity at irregular time intervals.

true

What is a hot spot?

unusual source of heat in upper mantle. Plates move over, get melted, form volcanoes

What are seismic waves?

vibrations caused by an EQ

The force pushing viscous magma to extrude during an eruption comes from what?

volatiles

What features can form on a planet if it has a hot, molten interior?

volcanic lava flows

How an earthquake happens

-Friction causes most faults to "stick" -rocks are elastic and stress builds up -After decades, stress overcomes friction, causes to snap

On average, how many damaging earthquakes occur each year?

1,000

What are three factors that determine the violence of a volcanoe?

1. Composition of the magma 2. temperature of the magma 3. dissolved gases in the magma

Where the lithosphere goes to die... 3 types:

1. Ocean-continent: denser ocean plate slides under continent (subduction) 2. Ocean-ocean: same as ^ 3. Continent-Continent: neither subducts. this creates big mountains

What are the three ways rocks can melt?

1. When temperature increases 2. Pressure decreases 3. Chemical Reaction: water is added to the rock

What are the 2 types of surface waves. explain them

1. rayleigh waves- result in vertical movement of surface 2. love waves- produce a side-to-side movement

How much would ground motion increase between a magnitude 4.5 and 5.5 earthquake?

10 times as much

When did Pangea break apart?

200 millions years ago

How much is the movement of plates away from each other at divergent boundaries annually?

5 cm per year

A volcanic arc is formed when which of the following conditions exists?

A piece of oceanic crust is subducted below continental crust.

If you were examining a map, what would you look for to indicate that subduction is happening?

A trench

Rocks melt at convergent boundaries because of:

Addition of water

Where do earthquakes occur?

Along plate boundaries where plates move

What were the most common plate boundaries when Pangea was being assembled

Continent-continent collision

How are continental rift magmas and continental arc magmas different?

Continental arc magmas are more viscous than continental rift magmas.

If you find a plate boundary in the middle of an ocean away from an edge, what type of plate boundary is it most likely to be?

Divergent

How are elastic rebound and elastic deformation different?

Elastic deformation causes objects to bend, whereas rebound causes objects to return to their original shape.

Where is the oldest crust found in relation to a plate boundary? (closer or farther from boundary)

Farther away from the boundary

What type of lava would be viscous (thick)?

Felsic

Which of the following events allows rocks on either side of a fault to rebound elastically, causing an earthquake?

Friction along the fault plane is overcome.

What are the two reasons volcanoes form?

Hot spots and plate tectonics

Two situations in which a small-magnitude earthquake can have high-intensity

If there is a large population in the area and the buildings are built on softer ground and not good building codes.

What causes an ocean trench?

Its the place where two plates meet on a convergent boundary and one subducts.

What type of lava lets gasses escape easily?

Mafic

What type of lava would be runny?

Mafic

What is the difference between magma and lava?

Magma is molten rock below the surface and lava is molten rock at the surface

What is the composition of the outer core of the earth?

Metal and liquid

How do volcanoes form?

When rocks melt, magma is less dense then surrounding rock so it rises straight through the crust forming magma chambers for volcanoes.

What kind of lava would a shield volcanoe produce?

Runny, mafic, basalt. Peaceful eruption

Magma occurs in the uppermost mantle because..

That's where temperatures are high enough and pressures are low enough

What is the magnitude of an earthquake?

The amount of energy released as the rock breaks

What is a divergent plate boundary?

When two plates are moving away from eachother

What are transform boundaries?

When two plates slide past each other

When two plates composed of oceanic lithosphere collide, what determines which one will subduct?

The plate composed of older, cooler lithosphere will subduct

The oldest oceanic crust is 180 million years old while the oldest rocks on the continent is 4 billion years old. why?

The rocks of the continents are never destroyed by subduction under a continent

Thermodynamics

Thermal energy-energy of vibrating atoms Heat- total thermal energy of all the atoms in a substance Temperature-the average thermal energy of all the atoms in substance Entropy- amount of disorder/disorganization in a system Melt-increase the entropy

What kind of lava would a composite volcanoe produce?

Viscious, felsic, rhyolite, explosive eruption

What is a convergent plate boundary?

When plates are moving together.

What causes ridges in the ocean?

When rocks are hotter so they are less dense and are higher

Elastic Rebound

When rocks can store energy until the stress becomes too much and they break

Which type of force is responsible for reverse fault formation?

compressional force

What type of stress is most directly associated with convergent boundaries?

compressional stress

85% of volcanoes are at what kind of plate boundary

convergent

What causes melting of material under divergent plate boundaries?

decompression of rocks

Rocks melt at divergent boundaries because of:

decreasing pressure

Which type of plate boundary is most closely associated with the formation of new ocean floor?

divergent

What features can form on a planet if it has an atmosphere?

dunes

Most earthquakes are the result of movement along which feature?

faults

What is a fault?

fractures along which rocks move

Describe a mafic rock.

has a lot of iron and magnesium that break up the silicon and oxygen chains

Describe a felsic rock.

has a lot of silicon and oxygen chains and very little iron and magnesium

What features can form on a planet with any characteristics?

impact craters

Rocks melt at hot spots because of:

increased temperature

Which type of force is responsible for normal strike-slip formation?

shear force

What type of stress is most directly associated with transform faults?

shear stress

Which of the following describes the type of deformation experienced by rocks before an earthquake?

slow deformation

What features can form on a planet if it has liquid on the surface?

stream beds

Which type of fault has NO vertical motion of rocks associated with it?

strike-slip fault

Which type of force is responsible for normal fault formation?

tensional force

What type of stress is associated with divergent boundaries?

tensional stress


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