A huge earthquake lurking beneath Bangladesh

Discussion in 'Earth Science' started by Plazma Inferno!, Jul 13, 2016.

  1. Plazma Inferno! Ding Ding Ding Ding Administrator

    A huge earthquake may be building beneath Bangladesh, the most densely populated nation on earth. Scientists say they have new evidence of increasing strain there, where two tectonic plates underlie the world's largest river delta. They estimate that at least 140 million people in the region could be affected if the boundary ruptures; the destruction could come not only from the direct results of shaking, but changes in the courses of great rivers, and in the level of land already perilously close to sea level.
    The newly identified threat is a subduction zone, where one section of earth's crust, or a tectonic plate, is slowly thrusting under another. All of earth's biggest known earthquakes occur along such zones; these include the Indian Ocean quake and tsunami that killed some 230,000 people in 2004, and the 2011 Tohoku quake and tsunami off Japan, which swept away more than 20,000 and caused the Fukushima nuclear disaster. Up to now, all known such zones were only under the ocean; this one appears to be entirely under the land, which greatly multiplies the threat. The findings appear in this week's issue of Nature Geoscience.
    Subduction-zone quakes generally occur where plates of heavy ocean crust slowly dive offshore beneath the lighter rocks of adjoining continents, or under other parts of the seafloor. Sometimes sections get stuck against each other over years or centuries, and then finally slip, moving the earth. Scientists knew of the plate boundary in and around Bangladesh, but many assumed it to be sliding only horizontally near the surface, where it sometimes causes fairly large, but less damaging earthquakes in areas that are not as densely populated. However, the authors of the new research say movements on the surface over the past decade show that subduction is taking place below, and that part of the plate juncture is locked and loading up with stress. They are not forecasting an imminent great earthquake, but say it is an "underappreciated hazard."


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