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The 11 April 2012 east Indian Ocean earthquake triggered large aftershocks worldwide
Pollitz, F.F.; Stein, R.S.; Sevilgen, V.; Bürgmann, R. (2012). The 11 April 2012 east Indian Ocean earthquake triggered large aftershocks worldwide. Nature (Lond.) 490(7419): 250-253. hdl.handle.net/10.1038/nature11504
In: Nature: International Weekly Journal of Science. Nature Publishing Group: London. ISSN 0028-0836, more
Peer reviewed article  

Available in  Authors 

Keywords
    Earthquakes; Seismic waves; Marine

Authors  Top 
  • Pollitz, F.F.
  • Stein, R.S.
  • Sevilgen, V.
  • Bürgmann, R.

Abstract
    Large earthquakes trigger very small earthquakes globally during passage of the seismic waves and during the following several hours to days, but so far remote aftershocks of moment magnitude M[thinsp][ge][thinsp]5.5 have not been identified, with the lone exception of an M = 6.9 quake remotely triggered by the surface waves from an M = 6.6 quake 4,800[thinsp]kilometres away. The 2012 east Indian Ocean earthquake that had a moment magnitude of 8.6 is the largest strike-slip event ever recorded. Here we show that the rate of occurrence of remote M[thinsp][ge][thinsp]5.5 earthquakes (>1,500[thinsp]kilometres from the epicentre) increased nearly fivefold for six days after the 2012 event, and extended in magnitude to M[thinsp][le][thinsp]7. These global aftershocks were located along the four lobes of Love-wave radiation; all struck where the dynamic shear strain is calculated to exceed 10-7 for at least 100 seconds during dynamic-wave passage. The other M[thinsp][ge][thinsp]8.5 mainshocks during the past decade are thrusts; after these events, the global rate of occurrence of remote M[thinsp][ge][thinsp]5.5 events increased by about one-third the rate following the 2012 shock and lasted for only two days, a weaker but possibly real increase. We suggest that the unprecedented delayed triggering power of the 2012 earthquake may have arisen because of its strike-slip source geometry or because the event struck at a time of an unusually low global earthquake rate, perhaps increasing the number of nucleation sites that were very close to failure.

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