GPS and gravity measurements along the western part of the North Anatolian Fault and their relation to crustal deformations

Abstract

The post seismic time dependent motions of 1999 Izmit and Düzce earthquake sequences in Marmara region ,Turkey, provide the opportunity to improve significantly our understanding of the mechanical behaviour of the western part of North Anatolian Fault. Therefore, an international cooperative project have been started to determine the long-term potential post seismic crustal deformations along the tectonic fault using GPS and gravity data sets in this region. We focus into the first results of joint gravity and GPS studies to understand 3-dimensions post seismic deformations of 1999 earthquakes along the North Anatolian Fault between the 2003 and 2005 years in the Marmara Region. The GPS data set following the 1999 earthquakes and the gravity observations were analyzed to detect of the accurate 3-dimension post seismic deformations and to determine gravity changes in time and space dependent on vertical crustal movements. The first results indicate that the gravity changes and some of the GPS time series show, strongly, seasonal unmodeled behaviours, and vertical motion from GPS field and gravity results shows good correlation. Furthermore, they show that height, gravity and potential changes between the western and eastern part of the network are very different. The western part shows significant strain loading, which is documented by horizontal displacements and potential increases.