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Large strike-slip earthquakes are not unprecedented in the diffuse boundary region separating the India and Australia plates, southwest of the Sumatra subduction zone. In 2012, two events of M 8.6 and M 8.2 on the same day (04/12/2012) ruptured a series of oceanic strike-slip structures 650-850 km to the north of the March 2, 2016 event. On June 18, 2000, a M 7.9 earthquake ruptured an oceanic strike-slip structure about 1000 km southeast of the March 2, 2016 earthquake. The focal mechanisms of the all of these earthquakes are consistent in implying that each event could have occurred as the result of left-lateral slip on an approximately north striking fault or right-lateral slip on an approximately west striking fault. The two different orientations of strike-slip faulting are both possible under the same tectonic stress field; perpendicular strike-slip faults that are both compatible with the same stress field are called "conjugate faults". In 2012, in-depth studies of those major events showed that faults of both orientations were involved in their rupture processes, breaking a network of conjugate faults over an area of ~ 200x200 km in size in the Wharton Basin. Because of the remote locations of these oceanic earthquakes, such events rarely cause shaking-related fatalities (the 2012 M 8.6 event caused two). Similarly, strike-slip earthquakes do not typically generate tsunamis.
originally posted by: muzzy
a reply to: Bishop2199
Also you can throw in "quiet periods", such as when there are NO further earthquakes AT ALL for several years inside that circle, ie. the crust is "locked". Anything that pops up eventually could be considered a "new" event. Sumatra might fit into this scenario, it has been a long time since there has been a M7 along the Aceh-Nias coast, enough time that I consider that Fault "locked" (and primed?).