Geodetic monitoring of the November 16, 2000 - New Ireland Earthquake

Abstract

On 16 November 2000 a Magnitude 8.0 earthquake occurred off the west coast of New Ireland, north of the Duke of York Islands. The event, a major left-lateral strike-slip earthquake, ruptured the Weitin Fault over hundreds of kilometres and caused massive horizontal land movements in the Gazelle Peninsula and New Ireland. The earthquake occurred on the boundary between the Pacific and South Bismarck Plates and represents a release of strain that has built up over several decades during the time that the plate boundary was locked. Measurements from a GPS monitoring network show co-seismic displacements ranging from 0.3 m in the west at Malasait to over 5.5 m near the fault at Weitin. Further to the east on the Pacific Plate, Lihir Island was displaced by 0.1m. Significant post-seismic relaxation has been observed at the continuously-operating GPS sites run by the Rabaul Volcano Observatory and at other sites in the Gazelle Peninsula and southern New Ireland. All pre-earthquake coordinate systems in the New Ireland/East New Britain regions (e.g. the PNG geodetic datum) will be distorted by amounts of up to 5m of more and some of this distortion is still continuing four months after the earthquake.