NOISE CHARACTERISTICS OF GPS COORDINATES IN A VOLCANIC REGION

The aim of this study is to estimate the noise characteristics in GNSS time series of permanent stations on the Soufriere Hills Volcano, Montserrat. Ground deformation measurements using geodetic space techniques can be very useful to monitor volcanic activity in order to asses the hazard situation. However, it is recognized that if noise parameters present in the data are not estimated, they will cause a bias in any subsequent deformation analysis. The GNSS-derived time series consists of a deterministic and stochastic part which can be characterized by estimation of trend, periodic variations and random noise. Maximum Likelihood Estimation (MLE) in our analysis will be used for detecting the type and amount of noise. MLE does not need the time series in regular intervals which is very advantageous for analyzing data affected greatly by interruptions caused by eruptions such as in volcanic regions. In this study, first outliers will be defined using the interquartile range method. Parameters of random noise, estimated amplitudes of the periodic functions, and the trend model, will be presented.