Seismic Evidence for a 920km discontinuity in the mantle,
Hitoshi Kawakatsu, Fenglin Niu
Nature, 371,
301-305, 1994.
Abstract
Analysis of hundreds of seismograms from a seismic array in the Japanese islands
reveals a seismic discontinuity at a depth of about 920 km in the mantle beneath
the Tonga subduction zone.
This discontinuity is also evident beneath subduction zones in the Japan and
Flores seas.
The discontinuity is probably due to either
a change in chemical composition or a subducted slab's granet layer.