Resumen

LIN, Jyh-Woei. Detecting Ionospheric Precursors of a Deep Earthquake (378.8 km) on 7 July 2013, M_w=7.2, in Papua New Guinea under a Geomagnetic Storm: Two-Dimensional Principal Component Analysis. Earth Sci. Res. J. [online]. 2013, vol.17, n.2, pp.135-140. ISSN 1794-6190.

Two-dimensional ionospheric total electron content (TEC) data were collected during the time period from 00:00 on 2 July to 12:00 UT on 08 July 2013. This period spanned 5 days before to 1 day after a deep earthquake (378.8 km) in Papua New Guinea at 18:35:30 on 7 July 2013 UT (M_w=7.2). Data were examined by two-dimensional principal component analysis (2DPCA) to detect TEC precursors related to the earthquake because TEC precursors have usually appeared in earlier time periods (Liu et al. 2006). A TEC precursor was highly localized around the epicenter on 6 July for 5 minutes, from 06:00 to 06:05. Ionizing radiation from radon gas release could possibly have caused the anomalous TEC fluctuation through, for example, a density variance. The plasma might have experienced large damping to cause short-term TEC fluctuations, and the gas released in a small amount in a short time period. 2DPCA can also identify short-term TEC fluctuations, but this fluctuation lasted for a considerable length of time. Other background TEC anomalies caused by the geomagnetic storm, small earthquakes and non-earthquake activities, e.g., equatorial ionization anomaly (EIA), resulted in small principal eigenvalues. Therefore, the detection of TEC precursors through large eigenvalues was not due to these background TEC anomalies.

Palabras clave : Ionospheric Two-dimensional Total Electron Content; Papua New Guinea; TEC anomaly; Two-Dimensional Principal Component Analysis; Anomalous TEC fluctuations; Equatorial Ionization Anomaly (EIA)).

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