Abstract
Two-dimensional principal component analysis (2DPCA) and principal component analysis (PCA) are used to examine the ionospheric total electron content (TEC) data during the time period from 00:00 on August 21 to 12: 45 on August 31 (UT), which are 10 days before the M = 7.6 Philippines earthquake at 12:47:34 on August 31, 2012 (UT) with the depth at 34.9 km. From the results by using 2DPCA, a TEC precursor of Philippines earthquake is found during the time period from 4:25 to 4:40 on August 28, 2012 (UT) with the duration time of at least 15 minutes. Another earthquake-related TEC anomaly is detectable for the time period from 04:35 to 04:40 on August 27, 2012 (UT) with the duration time of at least 5 minutes during the Puerto earthquake at 04: 37:20 on August 27, 2012 (UT) (M w = 7.3) with the depth at 20.3 km. The precursor of the Puerto earthquake is not detectable. TEC anomaly is not to be found related to the Jan Mayen Island earthquake (M w = 6.8) at 13:43:24 on August 30, 2012 (UT). These earthquake-related TEC anomalies are detectable by using 2DPCA rather than PCA. They are localized nearby the epicenters of the Philippines and Puerto earthquakes.
Highlights
Principal component analysis (PCA) has been used to detect the ionospheric total electron content (TEC) precursors regardless of nonearthquake TEC disturbances from Lin’s statistical work [7] about principal component analysis (PCA)
From the results by using 2DPCA, a TEC precursor of Philippines earthquake is found during the time period from 4:25 to 4:40 on August 28, 2012 (UT) with the duration time of at least 15 minutes
Another earthquake-related TEC anomaly is detectable for the time period from 04:35 to 04:40 on August 27, 2012 (UT) with the duration time of at least 5 minutes during the Puerto earthquake at 04: 37:20 on August 27, 2012 (UT) ( Mw = 7.3) with the depth at 20.3 km
Summary
Principal component analysis (PCA) has been used to detect the ionospheric total electron content (TEC) precursors regardless of nonearthquake TEC disturbances from Lin’s statistical work [7] about PCA. PCA assigns large principal eigenvalue, that is, principal eigenvalue >0.5 in a normalized set to the earthquake-related TEC anomaly (TEC precursor). Computing time is saved, and principal eigenvalue can represent main characteristics of data [1]. In this paper, both two-dimensional principal component analysis (2DPCA) and principal component analysis (PCA). The examined ionospheric total electron content (TEC) data are during the time period from 00:00 on August 21 to 12:45 on August 31, 2012 (UT), which are 10 days before the Philippines earthquake. Examined period is selected for having the TEC data of 6 days before the Puerto earthquake, and the TEC precursor of this earthquake is possible to be detected. The TEC data are acquired from the NASA Global Differential GPS (GDGPS) system
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