Tectonic Plate Boundaries and Earthquakes

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What is the best indicator of where earthquakes will happen in the future?

Areas that experienced earthquakes in the past will likely experience earthquakes again.

Describe what causes an earthquake.

As two plates move past one another, the plates can get stuck and stop moving. Stress builds up where the plates are stuck until they eventually break and suddenly move apart, resulting in a rapid release of energy as earthquakes

What are the 4 types of plate boundaries?

1) Divergent, 2) Convergent (Oceanic-Continental), 3) Convergent (Continental-Continental), and 4) Transform

What does the word tectonic mean?

It describes the forces that shape Earth's surface and the rock structures that form as a result.

Describe the modified Mercalli scale.

It measures earthquake intensity based on descriptions of the earthquake's effects on people and structures.

What type of forces happen at a divergent boundary?

Tension

What is the theory of plate tectonics?

That Earth's surface is made of rigid slabs of rock, or plates, that move with respect to each other.

Describe the moment magnitude scale.

A magnitude scale measures the total amount of energy released by the earthquake.

Describe the Richter scale.

A magnitude scale uses the amount of ground motion at a given distance from an earthquake to determine magnitude.

Where is the energy from an earthquake the strongest on the Earth's surface?

At the epicenter.

What type of forces happen at a convergent boundary?

Compression

What land features form as a result of a divergent boundary?

In ocean = mid-ocean ridge; on a continentent = rift valley

Where could you find a divergent boundary?

In the ocean or on a continent

What are the 3 types of seismic waves?

P-wave (primary), S-wave (secondary), Surface waves.

What are the 3 types of scales used to describe earthquakes?

Richter, moment magnitude, and modified Mercalli scales.

What do scientists use to map the layers of the earth?

Seismic waves

Who studies earthquakes?

Seismologists

What type of forces happen at a transform boundary?

Shear

What are the 3 types of faults?

Strike-Slip - blocks of rock move horizontally past each other; Normal - As two blocks of rock diverge, one block of rock moves down relative to another; Reverse - As two blocks of rock converge, one block of rock moves up relative to the other.

Describe subduction.

Subdiction happens at a oceanic-continental convergent boundary where the oceanic plate slides underneath the continental plate.

What is the place called where subduction takes place?

Subduction Zone

What layer of the earth do the tectonic plates "float" on top of?

The asthenosphere which is semi-plastic.

What is the place called where rocks first begin to break and move resulting in an earthquake?

The focus

What layer of the earth are these plates that move?

The lithosphere, which is made up of the crust and the uppermost mantle.

What is the epicenter of an earthquake?

The location on Earth's surface directly above the earthquake's focus.

How do compression forces affect the lithosphere?

They thicken it.

How do tension forces affect the lithosphere?

They thin it.

Are mountains still being formed?

Yes, for example, the Himalayas grow a few millimeters each year due to compression.

What is a split or crack in the Earth's crust called?

a fault

What is a place called where there are many faults?

a fault zone

Where do most earthquakes occur?

along active plate boundaries; in the oceans and along the edges of continents.

Where could you find a transform boundary?

at the edge of two plates, usually an oceanic plate and a continental plate.

What land features form as a result of a transform boundary?

faults and earthquakes

Describe tension forces.

forces that are pulling apart

Describe compression forces.

forces that are squeezing or pushing together

What land features form as a result of a convergent (oceanic-continental) boundary?

in the ocean = deep ocean trench; on land = volcanoes

What land features form as a result of a convergent (continental-continental)boundary?

mountains

What type of motion happens at a divergent boundary?

moving away or separating

What type of motion happens at a transform boundary?

moving past each other or sliding in opposite directions

What type of motion happens at a convergent boundary?

moving towards or collision

Describe shear forces.

parallel forces that act in opposite directions next to each other.

What instrument do scientists use to measure and records ground motion and determine the distance that seismic waves travel.

seismometer

What is convection?

the circulation of material caused by differences in density. The difference in density is caused by the difference in temperature.

What is a seismic wave?

the energy released (vibrations) as a result of rock movement and rocks breaking along faults.

What are earthquakes?

the vibrations in the ground that result from movement along breaks in Earth's lithosphere, called faults.

What method do scientists use to locate an earthquake's epicenter?

triangulation

Where could you find a convergent (oceanic-continental) boundary?

where an ocean and a continent meet (shore)

Where could you find a convergent (continental-continental) boundary?

within a continent


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