Earth Science - Chapter 5 Plate Tectonics
where is a shallow focus located
0-70km
how many more times powerful is a magnitude 6 earthquake to a magnitude 4 earthquake
100x
about how many major tectonic plates are there
12
how thick is the inner core
1220 km
when was the last major earthquake in the Pacific Northwest
1700
how thick is the outer core
2260km
how thick is the mantle
2890 km
how long ago did the Asia and African plates collide
40 million years
how thick is the curst
5-70 km
where is an intermediate focus located
70-300 km
what is an example of a composite volcano
Mt. St. Helens
what is formed as a result of diverging plate boundaries
Ocean ridges and rift valleys
what can be produced from the information given from a seismogram
a distance-time graph which can reveal the focus of the earthquake
What is an earthquake
a massive release of energy that shakes the crust
what is a plate boundary
an area where two plates are in contact
what is a volcano
an opening in the EARth's surface ther ealeases gases, rocks, and melted rocks
what direction do plates move in a divergent plate boundary
apart
what are ridge plates
as magma cools when it reaches the surface, itpushes aside old, solidified magma.
what causes diverging plate boundaries
as magma rises between plates, it cools creating new lithsophereic plate material which pushes the older rock away
how does a composite volcano occur
as thick magma reaches the surface, it cools, hardens, and traps gases below. the pressure builds, and there is an eruption.
what is the crust made up of in the ocean
basalt
which rock is more dense, basalt or granite
basalt
what is a primary seismic wave
body wave first to arrive ground squeezes and stretches the direction of the wave travel can travel through all states of matter
what is a secondary seismic wave
body wave second to arrive ground motion is perpendicular to direction of wave travel can only travel through solids
what happens during continental-continental plate convergence
both continental plates have similar density so subduction does NOT occur plates move slowly together, crumple and fold, forming great mountain ranges like the Himilayas
what are the three types of volcanoes
composite volcano shield volcano rift eruption
what can result from oceanic-continental plate convergence
cone-shaped volcanoes can form from magma seeping to the surface volcanic belts mountain ranges like the Coast mountain range earthquakes
what keeps tectonic plates in motion
convection currents ridge push slab pull
what are the five layers of the earth
crust upper mantle lower mantle outer core inner core
where is the focus of an earthquake
deep underground, the spot where the earthquake originates
what are seismometers
devices used to measure seismic wave energy now seismometers can measure horizontal and vertical movement produce seismogra
what are the three types of ways plates can interact
diverging plate boundary convergent plate boundary transform plate boundary
when do earthquakes happen in BC
every 200-800 years
how many layers does the earth have
five
where are tectonic plates located
floating on the asthenosphere they are the lithosphere
what is the crust made up of on land
granite
where is a deep focus located
greater than 300 km
how does the area's type of geology affect how intense an earthquake is
harder the bedrock, the less shaking clay, sand, gravel, and other loose sediment may increase the intensity of the shaking liquefaction may happen if there is ground water
what is found in subduction zones
large earthquakes and volcanoes
what is the outer core composed of
liquid iron and nickel
where are rift eruptions found
long cracks in the lithosphere spreading ridges or rift valleys
what is the asthenosphere
molten layer of the upper mantle
what is the inner core composed of
mostly solid iron. tremendous temperature and pressure
where are transform plate boundaries found
near ocean ridges
where are composite volcanoes usually found
near subduction zones where there are convergent plate boundaries
what can be the result of a transform plate boundary
no mountains or volcanoes earthquakes and faults are very common
what happens during a rift eruption
non explosive massive amounts of lava spew out in a curtain like fountain
where are shield volcanoes found
not at plate boundaries, but at hotspots
what are the two types of tectonic plates
oceanic and continental
what happens during oceanic-continental plate convergece
oceanic plates subducts unde r the continental plate forming a trench
what are the three types of convergent plate boundaries
oceanic-oceanic oceanic-continental continental-continental
how thick is the earth
over 6000km
what are the three types of seismic waves
primary (p-wave) secondary (s-wave) surface (L-wave)
what is a seismogram
produced from a seismometer that shows when an eqrthquake started, how long it lasted, and the magnitude
what is the cause of the heat that keeps the asthenosphere molten
radioactive decay
what is a rift valley
rising magma that breaks through the continental crust pushing away old rock creating a ridge that continuously grows
what is a spreading ridge
rising magma that breaks through the ocean floor pushing away old rock creating a ridge that continuously grows
draw a convergent plate boundary symbol
see package
draw a divergent plate boundary symbol
see package
what way do plates move at a transform plate boundary
slide past each other int he opposite direction
what seismic waves cause the most damage
surface waves
where do 95% of earthquakes occur
tectonic plate boundaries
in the richter scale, what does 1 increase in magnitude mean
that the earthquake is 10x stronger than the previous
what are examples of a shield volcano
the Hawaiian Islands the Yellowstone National park volcanoes
what is subduction
the action of one tectonic plate pushing below another tectonic plate when a more dense oceanic plate subducts under a lighter continental plate
how does the distance to the epicenter affect how intense an earthquake is
the closer to the epicenter, the greater the shaking because there is less distance to ravel
what is mantle convection
the convection currents that occur as magma is heated in the asthenosphere
what happens during oceanic-oceanic plate convergence
the cooler, denser oceanic plate will subduct under the less dense oceanic plate.
what is the thinnest layer of the earth
the crust
what is the lithosphere
the crust and the upper part of the upper mantle
what determines how two plates will interact
the direction the plates are moving and the type of plate
what does the intensity of earthquakes depend on
the distance to the epicenter the area's type of geology
what is a seismic waves
the energy that earthquakes release
what is the thickest layer of the earth
the mantle
what causes volcanic formations
the movement of tectonic plates
what is the crust of the earth
the outer solid rock layer of the earth
what is liquefactio
the process in which the vibration of the seismic waves causes ground water to rise to the surface, turning solid ground into a liquid-like material
what can scientists tell from seismic waves
the source and strength of an earthquake the composition and distance of the Earth's interior because seismic waves behave differently in Earth's different layers
where is the epicenter of an earthquake
the spot on the continental crust that is directly above the focus
what is seismology
the study of the waves released by earthquakes
what is the mantle of the earth
the thickest layer mostly solid expet for the upper mantle being able to flow like toothpaste
what is the asthenosphere
the upper mantle
why is it hard to predict an earthquake's timing, exact location and strength?
their pressure builds up underground and over very long periods of time
occurs during a shield volcano eruption
thing magma flows out from a hotspot and forms a low, wide cone
what way do plates move in a convergent plate boundary
together
what is a surface wave
travels along Earth's surface last to arrive ground motion is a rolling action, like ripples
what can result from oceanic-oceanic plate convergence
volcanic island arcs in the form of long chains of islands for example Japan, Indonesia and Alaska
what are composite volcanoes
volcanoes with a build of of ash and thick lava which forms a tall cone
why is british columbia predicted to have a massive earthquake
we are sitting near all three tectonic plate boundaries: the Pacific plate is at a transform boundary with the Queen Charlotte Fault the Juan de fuca plate is subducting under the North American plate the Juan de fuca plate is diverging with the pacific plate
what are hotspopts
weak areas of the lithosphere
when do earthquakes occur
when moving tectonic plates can no longer resist the stress caused by friction working against convection currents
what is slab pull
when the denser plate material pulls the rest of the attacheded plate towards the subduction zone and down into the mantle
