Earthquakes And Tsunamis

1. Earthquakes And Tsunamis By: Colin Hetherington

2. What is an Earthquake? • A series of vibrations induced in the earth's crust by the abrupt rupture and rebound of rocks in which elastic strain has been slowly accumulating. (definition from http://dictionary.reference.com/browse/earthquake) • Earthquakes are most often caused from the shearing within Transform Boundaries. • The most common definition is: movement along a fault. • When the shearing between two plate tectonics erupt in an earthquake two different seismic waves are sent out from the focus (or the point beneath Earth’s surface where plate tectonics break under stress and shift). • P-Waves = Primary Waves = fastest wave that travels through anything. • S-Waves = Secondary Waves = slower wave that travels through everything but liquid. • Surface Waves = slowest waves that travel through buildings.

3. Additional Info. • As already stated, S-Waves are unable to travel through liquid resulting in what is referred to as a shadow zone (where no S-Waves occur). • The seismic waves that most humans feel are the Surface Waves which cause the collapsing of buildings and the shaking of the ground. • Obviously earthquakes only occur in regions along Fault/Boundary lines. • The reason for the sudden release in energy, is that when the two large tectonic plates pass by each other, they do not glide easily, but rather shear and get stick on rocks until they suddenly break under the pressure. This is the energy that creates the seismic waves. Earthquake Focus

4. Damage • The damage caused by an earthquake entirely depends on where the seismic waves strike. For example if an unpopulated region is struck by an earthquake, there will be minimal loss of life and property. On the other hand, if a densely populated area is hit by an earthquake, the amount of life and property damage will be very high. • Most commonly earthquakes destroy buildings, homes, bridges, telephone poles, dams and other structures. • Not only are earthquakes themselves bad they often trigger a chain of disasters such as landslides, tsunamis, floods, and aftershocks. • Scientists are sometimes able to predict large earthquakes from the small tremors on a fault line. • When caught in an earthquake stay clear of power lines, windows, and trees (falling materials) and hold onto something sturdy.

5. Examples The most recent (LARGE) earthquakes have occurred in … • Japan • Haiti • Chile • New Zealand • Phillipines Haiti = Chile = Philippines = New Zealand = Japan =

6. Historic Earthquakes • The Largest earthquake in history (our recorded history) was in Chile on May 22, 1960 when 9.5 earthquake struck. • But the most deadly earthquake in recorded history has occurred in Shaanxi, China in 1556 when 830,000 people were killed

7. What are Tsunamis? • Tsunamis are an unusually large sea wave produced by a seaquake or undersea volcanic eruption (definition from http://dictionary.reference.com/browse/tsunami). • Tsunami waves are very fast traveling at around 600 mph (the speed of a jet plane) therefore offering little time for coastlines to evacuate. For example if a Tsunamis was generated on the far side of the Pacific Ocean, within 24 hours the waves would have reached the California coastline. • Just like earthquakes, tsunamis most often occur near Transform Boundaries.

8. How Tsunamis Form • Tsunamis most often are caused by very large earthquakes occurring near or under the ocean (in other instances underwater volcanoes, land slides and very rarely meteorites cause tsunamis). • It is important to know that not all earthquakes generate tsunamis. (Must occur underneath water, be large and create movements in the sea floor. • The process in which tsunamis are generated from earthquakes is much more complicated than sudden push against a column of ocean water. An earthquakes magnitude and depth, water depth in the area, the amount of vertical motion of the sea floor, the velocity of such motion, whether there is slumping of sediments and the efficiency with which energy is transferred from the earth’s crust to the ocean water are all factors in the generation of tsunamis. • Although when created these waves only reach to an average height of around 3 in. and above (un-noticeable to a fisherman), as they get closer towards the shore/coast and the water becomes shallower their waves become much larger at around 50-100 feet.

9. Damage • As expected only areas near or on the shoreline can be effected from tsunamis. • As stated earlier, tsunamis can reach a height of 50-100 ft, this large increase in height allows extensive flooding about 1000 ft or more into the coastline. • Obviously, the main type of damage caused by a tsunamis is large amounts of flooding. Flooding to these extremes are so severe the ruin the land, buildings, transportation and communication lines. • Unfortunately scientists still are unable to exactly predict tsunamis, but are able to predict the most likely locations. (But a noticeable sign of a tsunami happens shortly before the coastline is hit, when the water reseeds far beyond the low-tide line) • When caught in a tsunami, the best action is to quickly travel to high ground or to the highest levels of buildings.

10. Examples of Tsunamis • Some of the most current locations for these disasters include: • Japan • Solomon Islands • Thailand • Chile • Indonesia

11. Historic Tsunamis • In our recorded history, the largest tsunami happened in Lituya Bay, Alaska on July 9, 1958. This tsunami created a wave height of 1720 ft. • The most deadly tsunami occurred in the Indian Ocean on December 26, 2004 . Killing over 230,000 people.

12. Current Disaster in Japan • As most people are aware, on Friday, March 11, 2011 Japan was hit by a 9.0 earthquake which was followed by a large tsunami. The earthquake was caused by transform boundaries near the Ring Of Fire. In fact, the archipelago of Japan supposedly moved 8 feet to the east and the earth’s axis moved about 4 in., due to the massive earthquake. Although the earthquake was enormous, the most deaths are coming from the devastating tsunami which has 21,459 confirmed deaths and over 20,000 missing. Its obvious that this is a very serious and drastic event as the problems keep coming from Japan. With the high levels of radiation coming from the leaking Nuclear Reactors and the damage cost reaching over 230 billion dollars. To donate go to: https://american.redcross.org/site/Donation2?5052.donation=form1&df_id=5052&idb=0

13. Videos of Tsunamis • http://www.youtube.com/watch?v=TRDpTEjumdo • http://www.youtube.com/watch?v=w9ygYqj4rVM • http://www.youtube.com/watch?v=1CFwY0ued0I • http://www.youtube.com/watch?v=CcFVxl8oclY Videos of Earthquakes

14. Fun Activities • http://tlc.discovery.com/convergence/quakes/interactives/makeaquake.html • http://www.edumedia-sciences.com/en/a98-tsunami#textual • http://www.stopdisastersgame.org/en/playgame.html

15. Website Sources • http://earthscience-longoria.blogspot.com/2009/04/how-and-where-earthquakes-occur.html • http://goiloilo.com/wp-content/uploads/2010/01/Haiti-Earthquake.JPG • http://www.beersteak.com/wp-content/uploads/2010/01/2010-haiti-earthquake.jpg • http://resources3.news.com.au/images/2011/02/24/1226011/183279-nz-earthquake.jpg • http://science.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/Science/Images/Content/earthquake-next-one-photo-rtre2o5-sw.jpg • http://static.howstuffworks.com/gif/tsunami-formation.gif • http://www.richmond.ca/__shared/assets/Tsunami_-_Fig12408.jpg • http://www.aheartforhaiti.com/images/Haiti-Earthquake-2010%287%29.jpg • http://www.doi.gov/emergency/images/Rev_Am_Sam_Pago_Pago1.jpg • http://www.abc.net.au/reslib/200903/r354220_1627020.jpg • http://www.celsias.com/media/uploads/admin/Tsunami_damage1.JPG • http://www.sciencemediacentre.co.nz/wp-content/upload/2010/12/earthquake-gallery-3.jpg • http://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami • http://qmackie.files.wordpress.com/2010/02/lituya-from-panoramio.jpg?w=500&h=521 • http://www.whatsonxiamen.com/news_images/505522.jpg • http://photos.upi.com/slideshow/lbox/28a2a62a7499abb8a957328e0867f9a9/88-magnitude-earthquake.jpg • http://library.thinkquest.org/04oct/01356/images/wave_model.jpg • http://www.calstatela.edu/dept/geology/GEOL351Images/TsunamiHotelDamage(2).jpg