Samoa Tsunami and Earthquake 2009!

Samantha, Kurtys and MJ 🙂

Brief Description

Samoa Islands is made up of nine volcanic islands, including the two large islands of Upolu and Savai’i and seven small islets. It is located about halfway between Hawaii and New Zealand in the Polynesian region of the South Pacific.

The Samoan Earthquake in 2009 was a devastating natural disaster that occured in the Island of Samoa. The disaster happened at the local time of  06:48:11am for at least two minutes on the 29th of September. It had a magnitude of 8.1 on the recta-scale, making it the most largest and destructive earthquake in 2009. A tsunami was generated from the earthquake which caused substantial damage and loss of life in Samoa, American Samoa, and Tonga. The Pacific Tsunami Warning Centre recorded a 3-inch (76 mm) rise in sea levels near the epicentre, and New Zealand scientists determined that the waves measured 14 metres (46 ft) at their highest on the Samoan coast.

There were more than 40 total aftershocks with a magnitude greater than 5.0 in the 48 hours since the initial earthquake.

The photograph above shows the devastation and loss of the Samoan people which resulted from the tsunamis and earthquakes around the coastal areas of the island.

Tectonic Plates

Tectonic plates are large plates of rock that make up the foundation of the Earth’s crust and the shape of the continents. The tectonic plates comprise the bottom of the crust and the top of the Earth’s mantle. There are ten major plates on Earth and many more minor ones. They float on a plastic-like part of the Earth’s mantle called the asthenosphere. The plates are most famously known for being the source of earthquakes, including the Samoan Earthquake in 2009.

The idea of moving plates was first developed in 1962 by Harry Hammond Hess.

This map, shows us the location of Samoa and the tectonic plates around the world. As seen, Samoa is positioned right on the edge between the Pacific Plate and the Australian-Indian Plate. Any land that is located on or surrounding the plates (e.g, Samoa, New Zealand, Papa New Guinea) are more likely to encounter earthquakes than the land far within the centre (e.g, Australia).

The major tectonic plates in the world are the:

African Plate

Eurasian Plate

Arabian Plate

Philippine Plate

Australian-Indian Plate

Antarctica Plate

Pacific Plate

Nazca Plate

North and South American Plate

Caribbean Plate

The video above is a sympathetic and painful slideshow revealing pictures of the destruction and despair of the Samoa earthquakes and tsunamis.

Cause of the Tsunami and Earthquake

A rupture in the ocean floor, possibly 300km long and 200km deep, caused the tsunami that devastated Samoa. The magnitude 8.1 earthquake would have pushed the crust on one side of the fault up to seven metres higher than the other side, scientists estimate. This generated waves that were more than three metres from crest to trough when they hit the Pacific islands, 200km to the north.

The quake occurred in one of the most geologically active areas of the world, where the Pacific plate is plunging westward under the Australia plate at a rate of 86 millimetres a year.

The quake’s magnitude suggests a fault rupture of between 200 and 300 kilometres, with one side of the fault moving up to 7 metres relative to the other, says Gary Gibson, a seismologist at environmental monitoring company Environmental Systems and Services, based in Melbourne, Australia.

The Samoa region is no stranger to tectonic activity. At the earthquake’s epicentre, the Pacific tectonic plate dives beneath the Australian plate at a rate of almost a centimetre a year, making the area one of the most active earthquake regions in the world. There have been around 30 quakes of magnitude 7.0 or more along this plate boundary since 1900. The slip of the fault during the quake would have uplifted and/or dropped swathes of the seafloor. This displaced huge amounts of water above – enough to generate a fast-travelling wave with a shallow height and a very long wavelength.

This zoomed-in image shows the movement of the two tectonic plates, Pacific Plate and Indian-Australian Plate. The direction in which the arrows are pointing at, reveal the positioning and locomotion between the two plates.

Result of the Tsunami and Earthquake

Several countries were also affected by the tsunami, including:
Samoa
American Samoa
Tonga
Fiji
The Cook Islands
Japan
The death toll was at least 129. In Samoa 77 people were reported dead, and 150 were injured. In American Samoa, at least 31 people were announced dead, 50 were injured, and a number missing. In Tonga, 9 people were reported dead, and at least 4 were injured.
A Channel 7 news report on the disaster, starring Kurtys Mayne and MJ Meafou.
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8 responses to this post.

  1. how did you guys post the youtube video, I can’t make mine work????

    Reply

  2. Our group has a youtube vid as well!

    Reply

  3. Have any other Tsunamis or Earthquakes occurred in Samoa since the one that you have talked about??

    Map: Your maps clearly indicated where Samoa is located and where the Tectonic plates are. With the map of where Samoa is located, you could make it a larger size so that it is easier to see and read.

    Description of Disaster: You gave a short and detailed description of the disaster highlighting the main events of the disaster. It is good because you haven’t repeated information numerous times.

    Explanation of the Plate Boundary near Disaster: You outlined the plate boundaries well, but could expand more on where they are.

    Overall Impression: Your description of you disaster and videos were well written and detailed. Good Work 😀

    Mark: 9/10

    Christchurch Earthquake

    Reply

    • Thank you for your comments and feedback on our PBL website. We will take into consideration the ways of improvement you have mentioned for the next time we do a similar task.

      Unfortunately there have been many other tsunamis and earthquakes in Samoa besides the one we have spoken about, because of the positioning of the island. They haven’t been as great as this 8.1 magnitude earthquake and 14 metre waves, and have not been reported in the media.

      MJ, Kurtys and Samantha. (:

      Reply

  4. In addition to our previoius coment:

    Have any other countries/continents, that are on the same fault line as Samoa, experienced earthquakes or Tsunamis?

    Christchurch Earthquake- Sarah, Beth, Carolyn and lauren

    Reply

    • Yes, New Zealand, Fiji and Papa New Guinea are also affected by the Australian-Indian Plate and the Pacific Plates movements.

      MJ, Kurtys and Samantha. (:

      Reply

  5. Hey Guys, Sichuan Earthquake group here.

    Map— The map was fantastic. It showed the plates which affected Samoa and the
    dreadful position in which the Island is located in. However, if the map was a bit
    more detailed, showing only the country and the plates around it by itself it
    would’ve been a bit more affective. Also, the map could’ve been a bit larger.

    Description of Disaster— The description also was fantastic, it was detailed and
    sophisticated. It showed the all the imformation of the
    Earthquake and Tsunami. A suggestion is that the
    information wasn’t very easy to understand (some bits).
    If you could word it in an easy, understandable manner it
    would be great!!!

    Explanation of Plate boundary near disaster- The explantion was also very good, it
    was detailed and sophisticated. However
    as i stated before you could’ve used
    easy/understandable language.

    Overall Impression- It was great, Detailed, Sophisticated, and I loved the video.
    Just the couple of errors i mentioned let you down. However
    overall FANTASTIC!!!!!!!!!!

    Rate: 8.5/10

    🙂 KEEP IT UP

    By: Dhaval, Kelly, Luke and Tim (Sichuan earthquake group)!!!!!

    Reply

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