Charles University in Prague, Faculty of Mathematics and Physics, Department of Geophysics, V Holesovickach 2, Prague, 18000 Czech Republic
Charles University in Prague, Faculty of Mathematics and Physics, Department of Geophysics, V Holesovickach 2, Prague, 18000 Czech Republic ; GeoForschungsZentrum Potsdam Section 1.3, Telegrafenberg, Potsdam, D-14473 Germany