Institute of Physics of the Earth, B Gruzinskaya 10, Moscow, 123810 Russian Federation ; US Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025 United States;
US Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025 United States
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964 United States