Irina S Zhelavskaya, Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany, Yuri Shprits, GFZ German Research Centre for Geosciences, Potsdam, Germany, Maria Spasojevic, Stanford University, Stanford, CA, United States and Nikita Aseev, University of California Los Angeles, Los Angeles, CA, United States