Today's magnitude-8.3 earthquake beneath the Kamchatka Peninsula was both extraordinarily deep and extraordinarily large. At 610 kilometers depth, it was pretty much as deep as earthquakes get. That's down near the bottom of the upper mantle. And at M8.3, it was one of the largest deep earthquakes yet recorded, "deep" among seismologists meaning below 300 km. These first-flush magnitude determinations can be adjusted by a few tenths of a unit, though, as the experts consults the details. The current record-holder is the M8.2 Bolivia event of 9 June 1994, so with further review the 24 May 2013 Kamchatka event may take the lead by a nose.
As always, my favorite post-quake entertainment these days is watching the seismic waves sweep across the USArray, courtesy of IRIS.
Background: "Deep Earthquakes"