Wednesday, April 3, 2013

Module #10

1. Choose one type of plate boundary (divergent, convergent, or transform). Choose one specific example of where this type of boundary exists (i.e. San Andreas Fault - California, USA) and complete the following: (Do not use the same example as any of your classmates)

a. Describe the motions of the plates involved at this boundary. Include the direction of movement of the plates and the rate at which they are moving

b. Describe some of the natural hazards / disasters that have occurred in recent history at this boundary. Include information on the geology of the event, the number of people killed, damage and any other relevant of interesting information.

2. Provide 2-3 useful websites (reliable sources) that provide useful and relevant information about this boundary.

3. Comment on at least 2 other postings from classmates. 


  1. At a convergent plate boundary, two plates collide. An a example of this is the ongoing collision between the Eurasian plate and the Indian plate. This collision has created the Himalayas. The Indian plate is moving north and colliding with the Eurasian plate. The Indian plate is colliding with the Eurasian plate at a rate of 2cm per year.

    Four major earthquakes have occurred in this region over the last 100 years. One of these major quakes was the Uttarkashi Earthquake that took place on October 14th 1991. It was caused by a slippage in the plate boundary. The official death count was 768 and 90 000 homes were damaged. 58 aftershocks were recorded after the quake and these lasted until November 28th 1991. It was the most deadly quake to hit the region since 1950.




  2. A diverging plate boundary occurs when two plates are being pulled apart from one another. One very popular diverging plate boundary is the mid Atlantic ridge. This ridge separates the Eurasian plate and the North American plate and the African plate from the South American plate. The plates left of the ridge move Westerly and the plates right of the ridge move Easterly. The ridge is spreading at a rate of 2.5 cm per year.

    A natural hazard that occurs due to the spreading of the plates is the volcanic and rifting activity occurring in Iceland. From 1975 to 1984 there were major episodes of rifting on the land. Rifting was triggered from the plates moving apart which lead to the ground rising and sinking which lead to further volcanic activity. Volcanic activity can harm many people and it has affected Iceland in many ways. Homes along the Mid Atlantic ridge are in danger from these plates separating.


  3. A transform boundary is a tectonic plate boundary at which two plates grind past one another in opposite directions. An example of this kind of fault is the San Andreas Fault in California. This is where the North American plate meets the Pacific plate. This boundary moves northwestward at about 2 inches per year.

    The most well known natural hazard on this boundary is the San Francisco earthquake on April 18, 1906. This massive quake was between a 7.7 and a 7.8 on the Richter Scale, it had a depth of 8 kilometers and caused more than 3000 deaths. It's considered to be one of the most devastating natural disasters in American History, alog with Hurricane Katrina and the Great Galveston Hurricane of 1900.


  4. A Transform Plate Boundary is one which, unlike the convergent or divergent boundaries, does not cause much visible damage to the lithosphere due to the fact that it only moves horizontally as opposed to vertically.

    The Alpine Fault is an example of a Transform Boundary (though it is also slightly a convergent boundary) between the Pacific plate and the Indo-Australian Plate. Located in New Zealand, it is 800 km long and runs along the western edge of the Southern Alps. The slip rate of the fault (the rate in which one plate moves in relation to the other) is 30 mm annually, with the Pacific Plate rubbing against the Indo-Australian plate towards the South-West.

    There have been no earthquakes at the Alpine Fault in recent history, the latest earthquake being in 1717. Many estimate that that earthquake had had a magnitude between 7.9 and 8.0, though because it was so long ago, unfortunately there are no statistics about casualties or any interesting facts to share beyond that. However, in terms of the next earthquake which will strike this fault, there is much information to be found. It is believed that, when considering the average time between the earlier earthquakes which have occurred at the Alpine, that the next will be in approximately 30 to 40 years. Many have claimed that the next earthquake will likely be a big one, with the tension increasing with every year it does not rupture. It is anticipated that there will be a horizontal offset of 8 m, as well as a vertical offset of 1.5 m (due to the fact that the Alpine, despite being mostly a Transform Boundary, has slight Convergent properties).


  5. A perfect example of a divergent plate boundary is directly through the middle of Iceland on the North American plate and the Eurasian plate. And traveling through this country is the mid-Atlantic ridge.
    These 2 plates are separating at a rate of approximately the rate at which your fingernails grow, which is 2 centimeters give or take a millimeter. Therefore, to put it into perspective, In the year 2100, Canada will be almost 1 full meter farther away from Europe.
    Since this is a divergent plate boundary, it is prone to volcanic activity and earthquake, which in turn can lead to tsunamis. Recently, in 1973, there was a massive volcanic eruption which began without warning with large tremors measured at 2.7 on the Richter scale. It left the island in a permanent evacuation due to the dangers it created to the population. This volcano destroyed over 400 homes, and lava flow threatened the harbors and therefore their main income of fishing. Fortunately, there were no deaths as everyone was evacuated within a matter of hours.
    Learn more!

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  7. A divergent plate boundary is formed when two tectonic plates move away from one another. An excellent example of this type of boundary is the Red Sea Rift, which is the spreading centre of the African Plate and the Arabian Plate. These two plate have been moving approximately 2cm apart for the last 30 million years, and have caused much seismic activity. This rift extends along most of the length of the Red Sea.
    The Jabal al-Tair volcanic island is located on this rift, and it erupted on September 30, 2007 after 124 years of dormancy. The eruption threw ash and lava high into the air and far out to the sea, killing several people (estimate is 3 souls) and necessitating evacuation of military bases and residential areas. About 2 weeks prior to the eruption, several minor earthquakes with 2 to 3.6 magnitude. This eruption and other minor seismic activity continues to effect shipping, the main concern being the potential for collision of lava and oil tankers, which could be a fire hazard. http://news.nationalgeographic.com/news/2006/07/060719-red-sea-parts.html

  8. A transform fault line is a strike-slip fault occurring at the boundary between two plates of the earth's crust.
    The fault line I chose is the Dead Sea Transform (also referred to as the Dead Sea Rift), it runs from the Maras Triple Junction and runs to the northern end of the Red Sea Rift. The fault runs across the African Plate on the west and the Arabian plate on the east. Both plates are moving in the same general north/north-east direction but the Arabian plate is moving faster.

    This fault line caused the 1138 Aleppo earthquake which was among the deadliest. It's name was naked from a the town Aleppo in northern Syria. It's death toll was 230, 000