basic structure of the earth. how do we know what is inside the earth? based on the speed and path...
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![Page 1: Basic Structure of the Earth. How do we know what is inside the Earth? Based on the speed and path of seismic waves as they travel through the Earth](https://reader036.vdocuments.us/reader036/viewer/2022082917/551495cc550346f06e8b5492/html5/thumbnails/1.jpg)
Basic Structure of the Earth
![Page 2: Basic Structure of the Earth. How do we know what is inside the Earth? Based on the speed and path of seismic waves as they travel through the Earth](https://reader036.vdocuments.us/reader036/viewer/2022082917/551495cc550346f06e8b5492/html5/thumbnails/2.jpg)
How do we know what is inside the Earth?
• Based on the speed and path of seismic waves as they travel through the Earth.– Speed/path of the waves are affected by
different densities.• In general, density increases with depth.• S waves cannot travel through liquid.
• http://www.pbs.org/wnet/savageearth/animations/index.html
![Page 3: Basic Structure of the Earth. How do we know what is inside the Earth? Based on the speed and path of seismic waves as they travel through the Earth](https://reader036.vdocuments.us/reader036/viewer/2022082917/551495cc550346f06e8b5492/html5/thumbnails/3.jpg)
Layers (Inside – Out)
• Inner Core– Large amount of pressure from above layers
cause the inner core to be solid and dense.– Made mostly of iron with small amounts of
nickel, oxygen, silicon, and sulfur
![Page 4: Basic Structure of the Earth. How do we know what is inside the Earth? Based on the speed and path of seismic waves as they travel through the Earth](https://reader036.vdocuments.us/reader036/viewer/2022082917/551495cc550346f06e8b5492/html5/thumbnails/4.jpg)
Layers (Inside Out)
• Outer Core– Liquid
• S waves cannot travel through this layer.
– Made mostly of iron
![Page 5: Basic Structure of the Earth. How do we know what is inside the Earth? Based on the speed and path of seismic waves as they travel through the Earth](https://reader036.vdocuments.us/reader036/viewer/2022082917/551495cc550346f06e8b5492/html5/thumbnails/5.jpg)
Layers (Inside – Out)• Mantle
– Largest layer– Made mostly of silicon, oxygen, magnesium,
and iron.– Often divided into the upper and lower mantle
• based on changing speed of seismic waves
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Layers (Inside – Out)
• Crust– Varies from less than 5 km to more than 60
km thick.– Contains more silicon and aluminum and less
magnesium and iron than the mantle.
![Page 7: Basic Structure of the Earth. How do we know what is inside the Earth? Based on the speed and path of seismic waves as they travel through the Earth](https://reader036.vdocuments.us/reader036/viewer/2022082917/551495cc550346f06e8b5492/html5/thumbnails/7.jpg)
Shadow Zone• Area between 105 and 140 degrees from
the earthquake in which no seismic waves are detected.– Due to the bending of primary waves and the
stopping of secondary waves at the boundary between the outer core and the mantle.
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MOHO (Mohorovicic) Discontinuity
• Boundary between the crust and the upper mantle (causes seismic waves to speed up)