Anomalous Geomagnetic Variations Possibly Linked with the Taiwan Earthquake (Mw=6.4) on 19 December 2009

Figure 7

Six-hours average values of the Pc 3 amplitude of the geomagnetic components (H, D, and Z) at the HLN station between August 2009 and January 2010 (band-pass filter (10–40 s)) and the Polarization ratio Z/H of Pc 3 (10–40 s) amplitude observed at the HLN station during the same period (the lower panel).