Deformation in the Pacific Basin from Lageos

Abstract

Measurements to LAGEOS have provided the means to determine the relative positions as a function of time for six laser tracking sites in the Pacific Basin. These relative positions, and the determined relative motions, have been used to generate a motion model that is compared to geological predictions. The motion of the central station in this sub-network (from the global SLR network) on Maui, Hawaii agrees well with that suggested by Minster and Jordan’s AM0–2 (1978) model when considered relative to the stations on the North American continent. The station at Yarragadee, Australia provides the longest record of continuous tracking (9 years). Its motion suggests a rate which is 11 mm/year slower than the 74 mm/year given by the AM0–2 prediction for the Austro-Indian plate at that location. The observed motion of Simosato, Japan does not conform to that predicted by the AM0–2 model for the Pacific, North American, or the Eurasian plate. The station at Huahine, in the Society Islands, appears to be moving south-west of the direction expected from the AM0–2 model by approximately 9° at a rate 11 mm/yr faster than AM0–2. The motion of Easter Island (on the Nazca plate) is expected to be better resolved when the 1988–1989 occupation is completed. The observed westward movement of Monument Peak in Southern California is an outcome of the so called “San Andreas anomaly” and provides an important link to sites located on the stable North American continent.