Time Series Analysis of Continuous GPS Data in Central Java 2010-2015

摘要

This paper is aiming at making an improvement in GPS data time series as an input in estimating velocity field in Central Java. In this research GPS observation data originated from Indonesia Continuously Operating Reference Station (InaCORS) 2010-2015 in Central Java are used and processed using GAMIT 10.6. Vienna Mapping Function 1 (VMF1) and daily IONEX data are used in data processing to improve GPS time series. Velocity is estimated by considering not only linear trend but also seasonal signals from time series analysis. It is found that by applying VMF1 and daily IONEX data has improved GPS time series by 0.14 mm in horizontal and 0.35 mm in vertical direction. The resulting velocity has improved 0.08 mm/yr in both horizontal direction and 0.16 mm/yr in vertical direction by canceling velocity bias due to seasonal signal. The results show that currently Central Java is moving at direction 103-121 degrees at rate 23.7-28.4 mm/yr and experiencing subsidence at rate 2-6 mm/yr, except in CBLR and CPKL stations. Central Java motion is may be influenced by post-seismic effect of 2006 M7.8 earthquake in the west part, inter-seismic effect in southeast part and Kendeng fault system in northeast part.