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PACIFIC SEA LEVELS RISING VERY SLOWLY AND NOT ACCELERATING

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Parker A., Ollier C.

Quaestiones Geographicae

2019

vol. 38

issue 1

179-184

Over the past decades, detailed surveys of the Pacific Ocean atoll islands show no sign of drowning because of accelerated sea-level rise. Data reveal that no atoll lost land area, 88.6% of islands were either stable or increased in area, and only 11.4% of islands contracted. The Pacific Atolls are not being inundated because the sea level is rising much less than was thought. The average relative rate of rise and acceleration of the 29 long-term-trend (LTT) tide gauges of Japan, Oceania and West Coast of North America, are both negative, −0.02139 mm yr−1 and −0.00007 mm yr−2 respectively. Since the start of the 1900s, the sea levels of the Pacific Ocean have been remarkably stable.

Using radar interferometry and SBAS technique to detect surface subsidence relating to coal mining in Upper Silesia from 1993-2000 and 2003-2010

75%

Nádudvari Á.

Environmental & Socio-economic Studies

2016

vol. 4

issue 1

24-34

In the presented research ERS1-2 and Envisat ASAR archive data were used for the periods 1993 – 2000 and 2003 – 2010. The radar images were acquired over Upper Silesia in southern Poland. DinSAR (Differential InSAR) and SBAS (Small Baseline Subset) methods were applied for the detection of the most subsided areas. The DinSAR images were layer stacked for an image using 26 interferometry pairs of ERS1-2 SAR and 16 pairs from Envisat ASAR images in an ascending-descending orbit combination. The stacking of these images showed the most subsided parts of these cities even under low coherent areas, but the results are less precise. In the Upper Silesian Coal Basin, intensive underground coal exploitation has resulted in several surface deformations under Bytom (~8-17 km2), Piekary Śląskie (~9-15 km2), Ruda Śląska (~32-42 km2) and Katowice (~20-23 km2) with 25-40 cm of subsidence (in general) in the studied time periods. The SBAS technique has also shown that coal mining caused subsidence in the cities of Bytom, Katowice, and Piekary Śląskie of 5-7 cm/yr. The presented SBAS method did not work for low coherent areas, e.g. dense forested areas. DInSAR data also pointed to several decreasingly less active mining areas, which relate to the mine closures in Bytom and Ruda Śląska, which is also verified by the time series analysis.

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1 Environmental & Socio-economic Studies

1 Quaestiones Geographicae

1 Nádudvari Á.

1 Ollier C.

1 Parker A.

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PACIFIC SEA LEVELS RISING VERY SLOWLY AND NOT ACCELERATING

Using radar interferometry and SBAS technique to detect surface subsidence relating to coal mining in Upper Silesia from 1993-2000 and 2003-2010