The Earth showed its usual pattern of earthquake activity in the week of January 9-15, 2013, with 31 tremors having a magnitude of at least 5 (≥M5.0) and 105 of ≥M4.0.
As expected, the tremors mainly followed the boundaries of the tectonic plates. Perhaps the most noteworthy feature of the USGS’s real time earthquake map was that there was only one tremor with a magnitude over 6.0 – an unusual, but not unprecedented, event.
Largest Earthquake This Week
In contrast to the usual, the largest earthquake recorded by USGS this week did not occur on any of the major subduction zones surrounding the Pacific Ocean or Indonesia. The M6.2 earthquake was located on the Pacific’s so-called Ring of Fire, in the Southern Ocean on the boundary between the Pacific and Antarctic plates.
The remote nature of this earthquake – its epicenter was over 2,500 km from Dunedin, New Zealand – and the fact that it affected no inhabited areas, means that very little information is available on it. However, the magnitude was large for a mid-ocean ridge earthquake. Quakes like these are typically smaller, because the rocks in such settings were formed relatively recently and are therefore warm, limiting their ability to build up strain.Decoded Science