Several deep earthquakes on the asthenosphere (area below the Pacific plate) have occurred since the Japan earthquake that Japan Meteorological Agency pegged at 8.5M. That general area is where the earth's largest volcano, Tamu Massif lies hidden until it was identified in 2013. I blogged something about that 3 days ago here.
Dutchsinse who recently raised issues related to a trusted geological agency's suddenly not reporting significant earthquakes occurring in various parts of the world, or making "mistakes" by reporting earthquakes that it said did not occur, or keeping the public puzzled by shutting off feeds at a time of heightened earthquake activity, has the following report:
An extremely deep magnitude 4.9 earthquake has occurred near the original large Japan 8.5M (7.8 magnitude revised) earthquake epicenter.
Measuring at a depth of 428 miles / 690km, this earthquake is one of the deeper earthquakes to occur in the recent past… just a few miles less the original Japan 8.5M event (which itself was very deep).
The area below the Pacific plate, where these earthquakes are occurring, is called the Asthenosphere. A deep layer of semi-melted magma, on which the plates rest atop.________At the start of this year (2015), scientists in New Zealand set out to do new tests / experiments on the Asthenosphere in order to determine the effect of deeper earthquakes on surrounding areas.
The findings determined something we’ve known (via research and reporting) for a fairly long time — deep earthquakes cause shallow larger earthquakes in nearby adjacent areas within days (or less) of the deep event occurring.
The shallow earthquakes are usually 1-2 magnitudes higher than the deep earthquakes, and usually strike at a shallow level to the West / Northwest of the deep epicenter.
Here is the video by dutchinse on the subject when the announcements were made in the media regarding the asthenosphere findings: