Damage to State Highway 73 from the 29 May 1995, Arthur's Pass earthquake

Abstract


 
 
 
 On 29 May 1995, a magnitude M 5.5 earthquake centred near Arthur's Pass caused considerable damage to State Highway 73 in Arthur's Pass National Park, almost a year after the highway was closed by a magnitude M 6.5 earthquake. Although earthquake magnitudes and epicentral locations for the two events accounted for some differences in extent and severity of slope failure and highway damage, the lower magnitude 1995 earthquake initiated significant rockfall above the Zig Zag, unaffected by the 1994 earthquake. The greater ground damage than anticipated at the Zig Zag and in Otira Gorge could be due more to direction of seismic wave propagation relative to Otira Valley, and predisposition of slope materials to failure, than to earthquake magnitude.