Seismic Waves
EQ: How do I describe and
identify different types of seismic
waves?
Seismic Waves
• Release of energy in the form of waves or
vibrations when stress in a rock builds up
enough to break or change shape
Include primary, secondary and surface
waves.
Seismic waves ripple out in all directions
from the point where the earthquake
occurred.
EQ: How do I describe and
identify different types of
seismic waves?
Primary Waves
• Longitudinal seismic waves
• Also known as P waves
• P waves move faster than other seismic
waves so they arrive at distant points
faster than other waves.
• Made up of compressions and rarefactions
of rock inside Earth
EQ: How do I describe and identify
different types of seismic waves?
Secondary Waves
• Transverse waves
• Also known as S waves
• Cannot travel through liquid
– Therefore, S waves cannot travel through the
Earth’s core
EQ: How do I describe and
identify different types of
seismic waves?
Surface Waves
• Occur when P and S waves reach the
Earth’s surface
• They travel slower than P and S waves but
they cause the most severe ground
movements
EQ: How do I describe and
identify different types of
seismic waves?
Tsunami
• Huge surface waves in the ocean caused
by earthquakes
EQ: How do I describe and
identify different types of
seismic waves?
Seismograph
• Records the ground movements caused
by seismic waves.
– P waves arrive at seismograph faster than S
waves
– By measuring the time between the arrival of
the two waves, scientists can tell how far
away an earthquake occurred.
EQ: How do I describe and
identify different types of
seismic waves?
Class Work and Homework
• Fill In
What did I learn
Confused
Say
Read pages 32 O – 34 O
Answer questions 1-4, page 34 O
Review and Reinforce 1-4
EQ: How do I describe and identify
different types of seismic waves?