New Zealand Journal of Geology and Geophysics abstracts

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The 1987 January Tokaanu earthquake sequence, New Zealand

STEVEN SHERBURN

Institute of Geological & Nuclear Sciences Ltd.
Wairakei Research Centre
Private Bag 2000
Taupo, New Zealand

Abstract The 1987 January Tokaanu earthquake sequence occurred at a shallow depth near the southern shore of Lake Taupo. Sixty-four earthquakes, in seven separate periods of activity were recorded over a 7 h interval; 26 earthquakes were located, with the largest of M_L3.6 occurring near the end of the sequence. The sequence had the characteristics of an earthquake swarm. Within the sequence, two adjacent clusters of epicentres were distinguished on the basis of waveform similarity and homogeneous station locations. Activity switched from one cluster to the other and back again, with both clusters sometimes active. Fluid overpressure may account for the switching by facilitating the rapid transfer of small stress changes between the two source regions. The sequence probably occurred where a northeast-southwest-trending fault was offset or sharply bent.

Keywords earthquake sequence; Tokaanu; Central Volcanic Region; asperity

Received 8 June 1992; published 13 April 1993
New Zealand Journal of Geology & Geophysics, 1991, Vol. 36: 61—68
0028Ð8306/06/3601—0061 ©The Royal Society of New Zealand 1991

PDF file of entire paper: medium quality (771K); (scanned from paper original: notes about this process). Digitisation of this article from the printed journal was kindly facilitated by the Geological Society of New Zealand

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