Download The Earth`s Internal Properties

The Earth’s Internal Properties
Homework: read Ch 12: pages 294-308
Seismic Waves
• Earthquake waves have revealed that the Earth is
______________
Waves travel through different mediums at different speeds
• Air is slower than water
• Water is slower than solids
Waves are measured on a ___________________
• Seismograph is the______________________
• ____________________ is the paper readout
• Modern ones electronic-seismometer
• Basic variety-heavy mass that resists
movement
Two types of seismic waves
• I. Body waves— travel through the Earth’s interior—two types
–
–
A. P-waves
B. S-waves
• II. Surface waves— travel on the Earth’s surface—two types
–
–
A. Love waves
B. Rayleigh waves
Body waves: two types
• Primary waves—p-waves
– _______________
– ___________________—expand
and contract
– Travel through _______+ liquid
 Secondary waves—swaves
– _____________________
– _________—vibrate up
and down and side to side
– Travel through _________
Surface Waves
• Rayleigh waves
• Love Waves
• Both are slower than body waves
Rayleigh Waves
• Move in an up and down
fashion
Love Waves
• Move in a side-to-side, ______like fashion
Earthquake terms
• __________________—the point on the surface
directly above the focus
• ________________—the exact location of the
break
Earthquakes are measured on the
_________________ ________________
• Each magnitude is ______times more powerful
than the preceding
How to Read a Seismogram
• The p-waves are the _______________to arrive
• The secondary are larger and arrive _________________
Locating Earthquakes
• Scientists draw lines perpendicular to the time from the first big
deviation of the p and s waves
________________ between arrival of p and s waves gives a
__________________ from the earthquake
Time Travel Curve
• Next they use a time-travel
____________
• The time ___________
between arrival times indicates
_____________
Locating an Earthquake
• The _____________ is where the _________
overlap
? How many stations do you need to locate an
earthquake? ______
Earthquake Lab
• Read the directions carefully
• USE PENCIL
Locating Earthquakes
1. Scientists draw lines perpendicular to the time from the first big
deviation of the p and s waves
2. Difference between arrival of p and s waves gives a distance from the
earthquake
3. Next use the Time Travel Curve
Fill out the concept map with the two main types of waves and
the two types of each of those waves. Fill out the bottom box with
the characteristics of those waves.
Seismic Waves
Two main types
Two types
1.
2.
1.
2.
1.
2.
1.
2.
Two types
1.
2.
1.
2.
1.
2.
1.
2.
Part II What Seismic Waves Tell Us
So . . . How do we know what the inside of the Earth is like?
Seismic Waves
•
Earthquake waves have revealed that the Earth is _____________
• Remember the different characteristics of different _________ waves
– _____-waves—solids and liquids
– _____-waves—solids only
Waves travel through different mediums at different s____________________
•
•
Air is slower than water
•
Andrija Mohorovièiæ studied seismographs and discovered waves pick up
______________________at a certain depth
•
•
He said, “Earth is _____________________”
Water is slower than solids
Earth's Internal Layers
Drew a map of the upper _____________________ of Earth's mantle,
Mohorovicic discontinuity
Cool geologists call it the ____________________________
Shadow Zone: Remember p and s waves
• 104 to 140 degrees does not receive any direct P waves
• The shadow zone results from S waves being ____________ entirely by
the _______________ core
• and P waves being bent (__________________) by the liquid core.
Shadow Zones—caused by refraction and s-waves cannot go through
liquid
Layers of the Earth
•
In Elementary and middle school you learned about crust, mantle, and core
The crust is the uppermost part of the _________________________
Lithosphere
•
The lithosphere varies
– from _______________ on the ocean floor
– to _________________at the mountain ranges
•
The crust is 10km thick under the oceans
– Made of ______________
•
Continental crust is between 20-60 km thick
– Made of _______________rocks that are less dense than basalt
The lithosphere is very narrow and is rigid and brittle. It floats on the
________________________.
The Mantle
• 3000 kilometers thick
• Hot iron-rich silicate rocks
• Behaves _______________________—a solid that flows
– Taffy example
• ______________ part asthenosphere
• Upper lithosphere includes _____________________
• ____________________________ _______________________ occur here
– Hot less dense material __________________
– Cooler more dense material __________________
Asthenosphere
• The lower part of the mantle is called the _______________________
•
Hot, iron-rich silicate rocks
•
•
The asthenosphere is hot and behaves with ___________________
It is a solid that ____________________like a liquid
Thermal convection currents occur here
Convection currents:
hot material rises,
cools, and begins to falls again.
The core is still the core.
The core has two parts:
• the inner and outer cores
1. Inner core: _______________iron and
nickel
2. Outer core: ___________________iron,
nickel & sulfur
The Earth's interior is _______________
1. Part of the heat and pressure is from _________________
2. Part is __________ ____________ from _________________ of the
Earth (sometimes called residual heat)
3. and part is from the decay of ___________________ elements
The Earth's inner core spins within the liquid outer core producing a
_____________________ _____________________
Function (Fxn) of magnetic field
• The magnetic field protects us from the ______________
_________________ - a high speed stream of radiation from the sun