Constraining crustal velocity fields with InSAR for Eastern Turkey: Limits to the block‐like behavior of Eastern Anatolia

Abstract

The Sentinel-1 satellite mission will enable global strain rate mapping from interferometric synthetic aperture radar (InSAR) and GPS data, and methods to combine these data in velocity fields will become increasingly important. Here we use InSAR to measure interseismic deformation in Eastern Turkey, across a ∼250,000 km 2 area that spans the Arabia-Eurasia plate boundary zone. From our InSAR data we first estimate slip rates and locking depths for the North and East Anatolian Faults (NAF and EAF) of 20 ± 3 mm/yr and ∼16 km and 11 ± 3 mm/yr and ∼16 km, respectively, but we also combine the InSAR data with existing GPS velocity measurements to construct high-resolution velocity and strain rate fields across the region for the first time. We calculate 2-D and 3-D velocity fields and find that strain is mainly localized across the NAF and EAF and that there is negligible differential vertical motion across the Eastern Anatolian plateau. We also show that high-resolution 2-D strain rate fields can be calculated from InSAR alone, even in the absence of GPS data. We fit a block model to our velocity field and estimate slip rates of ∼21 mm/yr and ∼8 mm/yr for the NAF and EAF, showing that our previous estimates differ from these values because they neglected crustal rotation. Although this rotation is an important component of the velocity field in Eastern Turkey, systematic residuals between our velocity field and the best fitting block for Anatolia suggest that the region is not block-like as proposed by previous authors.

Decomposing DInSAR Time-Series into 3-D in Combination with GPS in the Case of Low Strain Rates: An Application to the Hyblean Plateau, Sicily, Italy

“…Indeed, a reduction of about 10% could be achieved for the interferograms of both tracks on average (Table 1), indicating a decrease of long-wavelength tropospheric noise. These improvements are on the order of what was observed for a similar study over Eastern Turkey [41]. Table 1.…”

“…For our study we chose a correction technique based on the 75 km resolution ERA-INTERIM weather model data from the European Center for Meteorological Weather Forecast (ECMWF) [40]. Due to the coarse resolution, weather models often fail to correctly represent the turbulent atmosphere, but they do reduce the topography-correlated and long-wavelength signal on average [39,41,42]. Therefore, diurnal, semi-diurnal as well as seasonal signals can be reduced within single interferograms.…”

Interseismic Deformation of the Altyn Tagh Fault Determined by Interferometric Synthetic Aperture Radar (InSAR) Measurements

“…It is widely used to estimate the slip rates of major faults [16,21,22,27,28] since Massonnet et al successfully extracted the coseismic deformation of the 1992 Landers earthquake [20]. Wright et al [21] werethe first to use InSAR for studying the interseismic deformation.…”

“…Wright et al [21] werethe first to use InSAR for studying the interseismic deformation. InSAR has been proven to be a important tool in researching the seismic cycle deformation after many successful applications in coseismic [20], postseismic [29] and interseismic [16,21,22,27,28] deformation. Walters et al [22] improved Wright and coworkers' results [21] by using SAR data from two different look directions, in their paper, they stated that the uncertainties in slip rate and locking depth are reduced up to 60% which is a huge improvement.…”

Correcting InSAR Topographically Correlated Tropospheric Delays Using a Power Law Model Based on ERA-Interim Reanalysis

“…Furthermore, weather conditions and sunlight dependency may reduce the quality of the multispectral imagery available for the study region. Following recent advances in the global atmospheric model (GAM), atmospheric models are now regarded as the most promising method of tropospheric correction for InSAR [22][23][24][25][26]. GAM provides atmospheric parameters (pressure, temperature, and humidity) that can be applied to calculate the refractivity equations and determine path delays.…”