PLATE TECTONICSThe earthquake in Japan on March 11, 2011 and the tsunami that occurred as a result of it, once again has shown us how vulnerable we actually are, living on tectonic plates that are constantly on the move.

This presentation will give you a better understanding of the scientific concepts of the cause of this earthquake, the scientific evidence of the continental drift and the effort of people to control the damage of these earthquakes

How do we know about these plates?Who are the scientists who contributed to our understanding of the plate tectonics?

CONTINENTAL DRIFT

Alfred Wegener (1880-1930) The world’s continents are in motion

Click here to see a movie about Continental drift

In 1912 Wegener published his book “ The Origins of Continents and Oceans”. He hypothesized in the book that, at one time, the continents were joined

together in a supercontinent: PangaeaEvidence to support this hypothesis:

Evidence for continental driftContinents fit along their continental shelves

Matching rock types and similar fossils found along the borders of these shelves

Similar types and structures of rock exist on continents on opposites sides of the ocean. The rocks also show similar climate changes. When the continents are reassembled, the mountain chains from a continuous belt have the same rock types, structures and rock ages.

Harry Hess and Robert Dietz

discovered theSEAFLOOR

SPREADING

SEAFLOOR SPREADINGThe mid-oceanic ridge is formed when new lithosphere wells up through convection movement and old lithosphere is recycled back into the asthenosphere at a deep ocean trench.

Hess published his ideas about seafloor spreading in 1962 in a paper titled: “History of Ocean Basins”

One of the evidences found for this seafloor spreading is the discovery of magnetic stripes.

Earth’s magnetic poles are not stationary: once in a great while the magnetic poles exchange positions: north becomes south, south becomes north. S

Magnetic reversal

N

Lithosphere

MAGNETIC STRIPES• Magnetic surveys show alternating strips of

normal and reversed polarity on both sides of the rift area

PLATE TECTONICS• The interaction of the plates at their

boundaries results in intense geological activity in those areas

• RING OF FIRE

•The ring of fire is a region of intense geological activity, because plates meet at convergent boundaries all along it.

•As a result earthquakes are common and many volcanoes are found along the Ring of Fire.

•Japan lies on the boundary of the North American Plate and the Pacific Plate which has shaken the country in the Pacific Ocean more than once….

KOBE EARTHQUAKE• The Great Hanshin earthquake, or Kobe

earthquake, occurred on Tuesday, January 17, 1995, in the southern part of Hyōgo Prefecture, Japan. It measured 6.8 on the Richter Scale. The focal point of the earthquake was located 16 km beneath its epicenter on the northern end of Awaji Island, 20 km away from the city of Kobe.

• Approximately 6,434 people lost their lives; about 4,600 of them were from Kobe. Among major cities, Kobe, with its population of 1.5 million, was closest to the epicenter and hit by the strongest tremors. This was Japan's second worst earthquake in the 20th century after the Great Kantō earthquake in 1923, which claimed 140,000 lives.

NEW BUILDING TECHNIQUES• The Kobe Earthquake was the

trigger for a renewal in building techniques: earthquake resistant construction.

• Japan has built many earthquake resistant constructions since then and was well prepared when a massive earthquake rocked its skyscrapers on March 11, 2011 in the Tohoku prefecture………

Earthquake resistant building

• This skyscraper was able to withstand the massive earthquake…..

• HOWEVER………

Click on:

swaying skyscraper

TSUNAMI

….the earthquake did not come alone….

The energy released by the quake generated huge seismic sea waves:

A TSUNAMI

A WALL OF WATER• A tsunami wave is usually less than 1

meter high when it gets close to shore. As it nears the shore, the shape of the shore compresses the wave length but increases its height. Tsunami waves can then reach heights of 30 meters above sea level.

This wall of water has caused major damage to buildings and structuresand has caused the death of about 18000People, click on: tsunami Japan

WHAT HAVE WE LEARNED FROM THE KOBE AND TOHOKU EARTHQUAKE?1 Earthquake damage can be limited by

earthquake resistant building. The Kobe earthquake was a catalyst for rapid change. The need to retrofit to an improved seismic standard drove immediate research to determine appropriate criteria and methods for repair and retrofit. The earthquake was the trigger for Implementing New Seismic Design Technologies in Japan.

2 The damage to the land and buildings depend on the type of earthquake, the type of seismic waves it causes, the amplitude and strength of the earthquake and position of the epicenter of the earthquake

3 An earthquake occurring at the ocean floor can cause a tsunami as well. The tsunami can cause major damage and can even be the beginning of a nuclear disaster.

4 Earthquake prediction is not very accurate, but a tsunami warning system can be effective. Warning the countries that are bordering the ocean through which the tsunami waves are traveling with a speed of about 500 miles per hour can save lives.

Science helps us understand phenomena such as earthquakes.

Science and technology help us to prevent damage and death.

NEXT CHALLENGE:HOW DO WE LIMIT THE DAMAGE

OF A TSUNAMI?

Slideshow by:Nienke Adamse4/9/2011

References:

REFERENCES

Hewitt, P.G., Lyons, S., Suchoki, J., Yeh, J. (2007) Conceptual Integrated Science Glenview, Il: Pearson Education, Inc.

Slide 1 picture Tohoku earthquake. Retrieved fromhttp://www.ecarolinewalters.com/?p=116

Slide 2 picture Continental drift. Retrieved from http://www-das.uwyo.edu/~geerts/cwx/notes/chap15/ancient.html

Slide 2 picture Alfred Wegener. Retrieved fromhttp://www.scientific-web.com/en/Geology/Biography/AlfredWegener.html

Slide 2 Movie Continental Drift. Retrieved fromhttp://www.youtube.com/watch?v=leTM6A4NOP4

Slide 4 picture matching continental shelves. Retrieved fromhttp://commons.wikimedia.org/wiki/File:Pangea_pl_gi_ubt.png

Slide 4 picture matching fossils. Retrieved fromhttp://www.suu.edu/faculty/colberg/Hazards/PlateTectonics/PlateTectonics.html

Slide 8 picture plate tectonics right. Retrieved from http://spot.pcc.edu/~aodman/GS%20107%20web/earth,venus,mars/earthmarsvenusindex.htm

Slide 8 picture Plate Tectonics left. Retrieved from http://geology.csupomona.edu/drjessey/class/Gsc101/Plate.html

Slide 9 picture Ring of Fire. Retrieved from http://pubs.usgs.gov/gip/dynamic/hotspots.html

Slide 10 picture damaged building. Retrieved from http://geoffropuff.com/2010/10/ichikashi-earthquake-drill

Slide 11 pictures earthquake resistant building. Retrieved from http://mceer.buffalo.edu/infoservice/Reference_Services/advEQdesign.asp

Slide12 Movie skyscraper. Retrieved fromhttp://www.youtube.com/watch?v=-xlUnl5jnIk

Slide 14 Movie Tsunami Japan. Retrieved fromhttp://www.youtube.com/watch?v=w3AdFjklR50

Slide 15 picture tsunami warning system. Retrieved from http://www.fullissue.com/wp-content/uploads/2010/12/Tsunami-warning-system.jpg