Features of Earthquakes (45) - PowerPoint PPT Presentation

About This Presentation
Title:

Features of Earthquakes (45)

Description:

Features of Earthquakes (45) Seismic waves generated by an earthquake travel through Earth. Ground moves forward and backward, up and down, and shifts from side to side. – PowerPoint PPT presentation

Number of Views:168
Avg rating:3.0/5.0
Slides: 17
Provided by: JUSTIN320
Category:

less

Transcript and Presenter's Notes

Title: Features of Earthquakes (45)


1
Features of Earthquakes (45)
  • Seismic waves generated by an earthquake travel
    through Earth.
  • Ground moves forward and backward, up and down,
    and shifts from side to side.
  • Ground ripples like waves do in water.

2
Origin of Seismic Waves
  • The point where this energy release first occurs
    is the focus (plural, foci) of the earthquake.
  • Seismic waves are produced and travel outward
    from the earthquake focus

3
Primary Waves
  • Three different types of seismic waves are
    produced.
  • Primary waves (P-waves) cause particles in rocks
    to move back and forth in the same direction that
    the wave is traveling.
  • Particles in rocks compress and then stretch
    apart, transmitting primary waves through the
    rock.

4
Secondary and Surface Waves
  • Secondary waves (S-waves) move through Earth by
    causing particles in rocks to move at right
    angles to the direction of wave travel.

5
Surface Waves
  • Surface waves cause most of the destruction
    resulting from earthquakes
  • Surface waves move rock particles in a backward,
    rolling motion and a side-to-side, swaying
    motion.
  • Surface waves travel outward from the epicenter.
  • Earthquake epicenter is the point on Earths
    surface directly above the earthquake focus.

6
(No Transcript)
7
Locating an Epicenter
  • Primary waves are the fastest, secondary waves
    are slower, and surface waves are the slowest.
  • Seismic waves from earthquakes are measured with
    an instrument known as a seismograph.

8
Seismograph Stations
  • Primary waves arrive first at seismograph
    stations, and secondary waves, which travel
    slower, arrive second. Surface waves arrive last.
  • If seismic waves reach three or more seismograph
    stations, the location of the epicenter can be
    determined

9
Basic Structure of Earth
  • At the center of Earth is a solid, dense inner
    core made mostly of iron with smaller amounts of
    nickel, oxygen, silicon, and sulfur.
  • Above the solid inner core lies the liquid outer
    core, which also is made mainly of iron.

10
  • Earths mantle is the largest layer, lying
    directly above the outer core.
  • It is made mostly of silicon, oxygen, magnesium,
    and iron.

11
  • In the area on Earth between 105 and 140 from
    the earthquake focus, no waves are detected.
  • This area is called the shadow zone.
  • Secondary waves are not transmitted through a
    liquid, so they stop when they hit the liquid
    outer core.
  • Primary waves are slowed and bent but not stopped
    by the liquid outer core.

12
  • The outer core and mantle are made of different
    materials.
  • Primary waves speed up again as they travel
    through the solid inner core

13
Layer Boundaries
  • Primary waves slow down when they reach the outer
    core, but they speed up again upon reaching the
    solid inner core.

14
  • __________ waves cause most of the
  • destruction during earthquakes.
  • A. Primary
  • B. Secondary
  • C. Surface
  • D. Tension

15
  • Which causes rock particles to move in the same
    direction that the wave is traveling?
  • Primary waves
  • Secondary Waves
  • Surface waves
  • Tertiary Waves

16
  • The outermost layer of Earth is called the
  • __________.
  • A. asthenosphere
  • B. crust
  • C. outer core
  • D. upper mantle
Write a Comment
User Comments (0)
About PowerShow.com