Perturbations of the Earth’s magnetic field as a precursor to M5.9 – North Atlantic Ocean 2017-07-27 17:53:25 UTC at a depth of 10.0 km. Detected by magnetometers at approx. 15:00 UTC in South America. Included several other related images, maps/instruments . Note the time stamps on the Geospace Ground Magnetic Perturbations At The Poles. https://plus.google.com/u/0/117300779230803580292/posts/244gP3cWBbY
