Reconnaissance report on highway damage from the 18 June 1994, Arthurs Pass earthquake

Abstract

The magnitude M 6.5 earthquake on 18 June 1994 centred about 20 km southwest of Arthurs Pass, caused considerable damage to State Highway 73 through Arthurs Pass National Park, closing the highway for several days and restricting traffic for more than a week. The most serious damage occurred in the Upper Otira Gorge where a large (5-10,000 m3) rock slide covered the road and partially dammed the Otira River. Other damage affecting the highway consisted of debris and rockfalls, and slumping along the edge of poorly compacted fills. Bridges and other structures were not damaged.
 Damage to the highway appears to be associated with site specific factors rather than proximity to the epicentre. The pattern of ground damage may be due to the effects of topography on the propagation of earthquake waves, and variations in rock mass quality and destressing of valley slopes.

Ground shaking intensity and damage at Lake Coleridge power station in the 18 June 1994 Avoca River earthquake

“…6 occurred in the Harper River area much closer to Lake Coleridge. Locations of the epicentre and these main aftershocks are shown in Figure 1 of the accompanying paper by Patterson and Bourne-Webb (1994). The power station is on the west side of Lake Coleridge close to the lower border of this Figure.…”

Principal earthquakes in New Zealand in 1994

“…One of the most significant earthquakes in New Zealand in recent years occurred on June 18, near Arthur's Pass [Paterson and Bourne-Webb, 1994;Pattie and Wood, 1994]. Its Richter magnitude was 6.6, so it was very comparable to the damaging shock in Northridge, Los Angeles, on January 17 [Norton et al, 1994] .…”

Recent studies of historical earthquake-induced landsliding, ground damage, and MM intensity in New Zealand

“…More detailed accounts are given of landsliding triggered by the 1929 Murchison (Buller) earthquake (Henderson, 1937;Pearce and O'Loughlin, 1985), although the complete landslide distribution was not mapped. Better descriptions are given of landslides caused by more recent larger earthquakes such as: lnangahua 1968 (Adams et al, 1968); Edgecumbe 1987 (Franks et al, 1989); Weber 1990 (Perrin 1990);Fiordland 1993(Van Dissen et al 1994; Ormond 1993 (Read and Sritharan, 1993); and Arthur's Pass 1994 (Paterson and Bourne-Webb, 1994).…”

“…However, landslide effects are poorly defined in previously published New Zealand versions of the MM scale (Eiby, 1966;Study Group of the NZNSEE, 1992). Prior to the 1997 EIL study, a few papers had been published on landslides during some New Zealand earthquakes (e.g., Speight, 1933;Henderson, 1937;Adams, et al, 1968;Pearce and O'Loughlin, 1995;Franks, et al, 1989;Paterson and Bourne-Webb, 1994). There were, however, no comprehensive overview studies of earthquakeinduced landsliding in New Zealand, and little published data correlating landsliding with MM intensities and other seismicity parameters.…”