New Zealand Journal of Geology and Geophysics abstracts

---

The 1943 Lake Hawea earthquake—a large subcrustal event beneath the Southern Alps of New Zealand

Martin Reyners

Institute of Geological & Nuclear Sciences
P.O. Box 30 368
Lower Hutt, New Zealand

Abstract  A re-assessment of both instrumental and macroseismic data for the earthquake felt widely in the South Island of New Zealand on 1943 May 08 indicates that it was a subcrustal M_L 5.9 event c. 50 km deep located near the head of Lake Hawea. This location places it in the uppermost mantle beneath the crustal root of the Southern Alps, within the dipping seismic zone defined by well-located smaller earthquakes. Both the rupture dimension of the 1943 earthquake and the planar nature of the dipping seismic zone itself imply that the uppermost mantle in this region is rigid on c. 10 km and c. 100 km length scales, consistent with recent numerical models of lithospheric deformation. Subduction of rigid mantle lithosphere provides an explanation for the unusual isoseismal pattern for the 1943 event.

Keywords  Lake Hawea; Southern Alps; continental collision; intracontinental subduction; subcrustal earthquake; mantle rigidity; isoseismal distribution

G03072; Received 10 December 2003; accepted 30 April 2004; Online publication date 23 March 2005
New Zealand Journal of Geology & Geophysics, 2005, Vol. 48: 147–152
0028–8306/05/4801–0147 © The Royal Society of New Zealand 2005

PDF file of entire paper: Print-quality (994K) | screen-quality (299K)

---

This year's abstracts | Journal home page | All abstracts | Publishing home page