Focal mechanisms of some recent large New Zealand earthquakes

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Abstract
The focal mechanisms of six recent New Zealand region earthquakes are presented. Two of these (1988 Jun 3, 1989 May 31) occurred in the Fiordland region within the Benioff zone. The Macquarie Ridge earthquake (1989 May 23, Mw 8.2) was the largest earthquake globally since 1977. It occurred about 800 km south of New Zealand but was felt in the southern part of the South Island. Its strike‐slip focal mechanism is consistent with the predicted plate motion direction. The focal mechanism of the Lake Tennyson earthquake (1990 Feb 10) is ambiguous but it is most likely a strike‐slip mechanism parallel to the local fault trends, although no fault break was observed. The first Weber earthquake (1990 Feb 19) appears to be a complex event and its focal mechanism probably indicates down‐dip tension in the subducting Pacific plate. The second Weber event (1990 May 13) had a thrust mechanism consistent with the plate convergence direction.