Does the Earth 'Flare' like the Sun does?
The medium for a solar flare is plasma, so nothing like that occurs in the Earth's core. The outer core fluid is highly conductive and has a low viscosity, so changes may occur in the core's field, but the mantle has enough electrical conductivity to filter out the more rapid changes (those with periods of roughly a year or less). See Merrill and McElhinny pp 49-51 for details. However, geomagnetic jerks have been observed. These are abrupt changes in the second time derivative of the Earth's magnetic field. Sometimes they are global, although mantle filtering can delay the jerk by different amounts at different locations on the Earth's surface.