What Caused the Sumatra Earthquake?


Quick Answer

Alexander Besant of the Global Post explains that the 2012 Sumatra earthquake resulted from up to five faults in the tectonic plates under the ocean floor. Besant makes reference to a study explaining that the faults acted in concert and slid sideways to create a series of massive ruptures, resulting in the 8.6 magnitude earthquake. He also notes that researchers believe this may signal the splitting of the Indo-Australian plate.

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Full Answer

Helen Shen of the international science journal Nature notes that a 2004 quake along with a 2005 quake in the same area may have also acted as a trigger to the 2012 large-scale event by adding to pent-up stresses in the plate’s middle region. The California Institute of Technology gives further insight to the 2004 quake by stating that the earthquake ruptured the greatest fault length of any recorded earthquake, a distance of more than 900 miles, which measures longer than the state of California. The institute also explains that the rupture did not tear apart the land all at once but rather progressed northward from the epicenter along the fault for about 10 minutes. Furthermore, the two tectonic plates that lie at the rupture suddenly broke free, causing the upper plate to slide back upward and to the west along the plate boundary.

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