Download Seismic Waves

Seismic Waves
Standard 8-3.2 Explain how
scientists use seismic waves
& Earth’s magnetic field to
determine the internal
structure of Earth.
Seismic Wave Behaviors EQ:
8-3.2
• How do primary, secondary,
and surface waves behave as
they travel through the Earth?
Earthquake Waves
• What are the 3 types of
seismic waves?
• Primary (P) Waves
(longitudinal)
• Secondary (S) Waves
(transverse)
• Surface Waves
Primary Waves
• move out from the
• How do primary
earthquake focus
waves behave
•
travel
the
fastest
as they travel
• move through solid &
through the
liquid layers of Earth
Earth?
• push & pull rock
• back-and-forth
motion in the
direction the wave is
moving
Secondary Waves
• How do secondary
waves behave as
they travel through
the Earth?
• move out from the
earthquake focus
• move slower than
primary waves
• move through solid
rock only
• move at right angles
to primary waves
causing rocks to move
up & down & side to
side
Surface Waves
• How do surface • form when P and S
waves reach the
waves behave
surface
as they travel
through the
• cause the ground to
Earth?
shake
• make rock sway
from side to side &
roll like an ocean
wave
Earth’s Internal Structure:
Seismic Waves EQ 8-3.2:
How do scientists use seismic
waves to determine the internal
structure of Earth?
Inside Earth
• Seismic Waves:
• scientists look at their
speed & direction to infer
what’s inside of the Earth.
• Ex.) Primary waves slow
down when they reach
liquid, & speed up when
they go through solids.
• These wave behaviors • liquid outer core b/c
waves slow down
cause us to infer what
solid inner core b/c
about the Earth’s core?
waves speed up
• How do we know the
mantle is denser than
the crust?
• earthquake waves
travel faster through
the mantle
Earth’s Internal Structure:
Magnetic Field EQ 8-3.2:
How do scientists use Earth’s
magnetic field to determine the
internal structure of Earth?
Inside Earth: Magnetic Field
• What is inferred to be
the cause of Earth’s
magnetic field?
• the movement of materials
in the outer core of Earth
• Why are iron and nickel • they are 2 easily
inferred to be in Earth’s magnetized metals
core?
• How will a compass
• it will align (line up) with
needle behave within
the lines of force of
Earth’s magnetic field?
Earth’s magnetic field
Cause and Effect
1. Cause/Density
crust: less dense
mantle: more dense
Effect/Speed
slower seismic waves
faster seismic waves
2. Cause
outer core spins
Effect
Earth’s magnetic field
3. Cause
iron & nickel easily
magnetize
Effect
inferred to be in Earth’s
core