Earthquakes at intermediate depths in south-west New Zealand

Abstract

Earthquake activity in the southern seismic region of New Zealand extends to intermediate depths. This has hitherto been suggested on the evidence of isoseismal patterns and seismogram characteristics, and is now confirmed by computation for the Lake Te Anau earthquake of 20 May 1965, for which 45 readings of P. supported by readings of p′, pP, sP, and PP, indicate a depth of 103 ± 5 km. This result adds to the reasons for classifying the region as an active margin between the New Zealand continental mass and the Tasman Sea.