A further earthquake at exceptional depth beneath New Zealand (Note)

In February 1975 a deep earthquake was located at a depth of about 600 km beneath North Taranaki, following three earlier events at similar depths in 1953 and 1960. Sorne stations record phases intermediate between P and S that appear to arise from phase conversion at the base of the volume generally occupied by deep earthquakes, which suggests that the bottom of the lithospheric material presumed to descend into the mantle is rnarked by a sharp boundary.