• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
10   a diversion, earthquakes and tsunamis
 

10 a diversion, earthquakes and tsunamis

on

  • 636 views

 

Statistics

Views

Total Views
636
Views on SlideShare
636
Embed Views
0

Actions

Likes
0
Downloads
7
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    10   a diversion, earthquakes and tsunamis 10 a diversion, earthquakes and tsunamis Presentation Transcript

    • Earthquakes and Tsunamis
    • Earthquakes
      • Late Thursday night (our time), an earthquake occurred of the coast of Japan.
      Earthquakes
      • Late Thursday night (our time), an earthquake occurred of the coast of Japan.
    • Earthquakes
      • One of the largest earthquakes since we’ve been measuring them (6 th strongest).
    • What is an Earthquake?
      • Earthquakes are movements of the earth that release pressure.
      • Occur along faults.
      • - planar breaks in rock where there is movement.
      • - occur in all sizes.
    • Faults
    • Faults
    • What Causes an Earthquake?
      • Build up of strain (gradual or sudden) deforms the earth until the elastic limit is reached – then things snap.
      • Elastic Rebound.
      • Energy is released in the form of seismic waves.
    • What Causes an Earthquake?
    • How do we Measure an Earthquake?
      • Most common way is by the Richter Scale.
      • Based on the amplitude of the seismic waves.
      • Scale is logarithmic! Difference in two whole numbers means in increase in vibrations by a factor of 10!
      • - ground that moves 1 inch in a 4.0 earthquake moves 10 inches in a 5.0 quake, and 100 inches in a 6.0 quake.
    • Where Does the Strain Come From?
      • Plate tectonics.
      • Outermost portion of our planet is broken into different pieces called plates.
      • The plates move all the time.
    • Tectonic Plates
    • Plate Boundaries
      • Most of the action occurs at the boundary between two plates.
      • Plates can move away from one another, towards one another, or just slide past one another.
    • Plate Boundaries
    • Convergent Plate Boundaries
      • When plates run into one another, the more dense plate is forced underneath the less dense plate, a process called subduction.
    • Convergent Plate Boundaries
      • When ocean material runs into continental material one gets a trench in the ocean, and a chain of volcanic mountains on the continent.
    • Convergent Plate Boundaries
      • When ocean material runs into continental material one gets a trench in the ocean, and a chain of volcanic mountains on the continent.
    • Convergent Plate Boundaries
      • When ocean material runs into ocean material one gets a trench in the ocean, and a chain of volcanic islands called an island-arc.
    • Convergent Plate Boundaries
      • When ocean material runs into ocean material one gets a trench in the ocean, and a chain of volcanic islands called an island-arc.
    • Earthquake Damage
      • Ground movement
      • Fire
      • Landslides
      • Liquefaction
      • Tsunamis
    • Earthquakes and Tsunamis
      • Sudden movement of the sea floor will displace a large volume of water.
    • Tsunami Speed
      • The speed of the tsunami is controlled by the depth of the water.
      • C (celerity) = √ g x d
      • where g is gravitational acceleration, and d is the depth of the water in which the wave is travelling.
      • Since g is a constant, the speed is mostly a function of water depth (wavelength also plays a role, but we’re neglecting it for now).
    • Tsunami Speed
      • Average depth of the ocean is 4000 m.
      • C (celerity) = √ g x d
      • C = √ 9.8 m/s 2 x 4000 m
      • C = √ 39,200 m 2 /s 2
      • C = 198 m/s
      • 1609 meters in a mile, 3600 seconds in an hour.
      • C = 198 m/s / 1609 m/mile x 3600 s/hr
      • C = 443 miles/hour!
    • Tsunami Speed
      • As the wave approaches the shore its speed decreases.
      • C (celerity) = √ g x d
      • Aside from slowing, other things happen to the wave as it enters shallower water.
    • Tsunami Occurrences
    • Indonesia, December 2004
      • 9.1 magnitude earthquake occurred only 8 miles deep.
      • Rupture was 1200 km long with 15 m of vertical displacement.
    • Indonesia, December 2004
    • Indonesia, December 2004
      • Magnitude 8.9.
      • Strong enough quake to affect our axis of rotation (a day on earth is now a little shorter).
      Japan, March 2011