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Ionospheric precursor detection for the M=7.6, 05 September 2012, Costa Rica earthquake under large geomagnetic storm activity: Twodimensional principal component analysis

Lin Jyh-Woei

Two-dimensional principal component analysis (2DPCA) is performed to detect ionospheric total electron content (TEC) anomaly related to earthquake undergoing geomagnetic storm activity. The time period of examined TEC data are 5 day before the M=7.6 Costa Rica earthquake at 14: 42:07 on 05 September 2012 (UT). A TEC precursor of this earthquake with large principal eigenvalues (>0.5) (Lin 2010) is found nearby the epicenter during the time period from 20:05 to 20:10 on 03 September 2012 (UT) with the duration time of at least 5 minutes by using 2DPA while TEC anomaly related to other smaller earthquakes is not detectable. TEC anomaly caused by the geomagnetic storm activity during the examined time period results in the small principal eigenvalues, therefore the detection of TEC precursor is regardless of the geomagnetic storm activity.