Monitoring Anthemounta’s active Fault by collocated GNSS and Gravity observations
21/09/2016 | 16:45 | Session 4: Global gravity field modelling
Author(s): Konstantinos Christodoulou, George Vergos, Dimitrios Natsiopoulos and Ilias Tziavos
Konstantinos Christodoulou, George Vergos, Dimitrios Natsiopoulos and Ilias Tziavos
The area around the city of Thessaloniki includes many active faults hence being tectonically active. The triggering of such faults can be attributed to either natural phenomena, like tectonic plate movement, and/or anthropogenic activities like extensive irrigation. The aim of this study was to detect and analyze Earth's crust deformations due to the active Anthemountas Fault in correlation with changes in the water table.
The Anthemountas Fault in is one of the biggest faults in Northern Greece, bounded by the region of Vasilika and ending in the Chalastra region. The fault branches pass through Angelochori, Agia Triada, Perea, Neo Rysio and Souroti and reach the village of Galarinos. In 2006, the fault was fractured with visible cracks on the Earth’s surface in the city of Perea, which after geological and geophysical prospecting was attributed to water over-pumping in the region. To that respect, and in order to monitor the behavior and evolution of this fault, fourteen geodetic benchmarks (BMs) have been established along the visible part of the fault (T01-T14) and three control points (K01-K03) in the region of Perea. The main concept was to establish repeated seasonal occupations at all BMs combining GNSS and relative gravity measurements. Moreover, repeated seasonal gravity surveys have been carried out at drilling for irrigation facilities around the metropolitan area of Perea at the same epochs as at the BMs. Finally, historical GNSS occupations were available for all these points in 2006 and 2008. In this work, we present the analysis of the estimated displacements from the repeated GNSS occupations as well as the corresponding temporal gravity changes. Three new sets of GNSS occupations and gravity observations in 2016 (January, April and July) have been acquired and analyzed relative to each other and relative to the 2006 and 2008 campaigns. Finally, conclusions on the correlation between position displacements and gravity variations with changes in the water table due to irrigation are drawn.