Studies are carried out on GPS data for the Mexico and Nias great earthquakes to separate co-seismic ionospheric disturbances (CIDs) from the equatorial plasma bubble (EPB) activity, which are linearly independent processes. The singular spectrum analysis (SSA) method is known for its robustness in separating such linearly independent components. The GPS-TEC data for the great 2005 Nias and 2017 Mexico earthquakes for plausible detection and separation of CIDs using the frequency domain SSA method. The CIDs emerged in the bandpass filtered VTEC data for some combinations of satellite and station pairs in the case of the Nias earthquake. But for the Mexico earthquake, EPB anomalies are dominant, and CIDs are not visible clearly. Interestingly, the CIDs corresponding to acoustic and surface waves for both earthquakes are visible after applying frequency domain SSA. Additionally, we have even determined the signatures of propagating gravity waves in the case of the Mexico earthquake, as it has generated a moderate tsunami. Thus, the present study demonstrates the first evidence for detecting CIDs or rules out the masking of CIDs associated with the earthquakes by the EPBs prevalent during the post-sunset time and hence valuable for early earthquake warning systems.
Citation: Rajesh, R., & Catherine, J. K. (2022). The first evidence for the detection
of CIDs masked by equatorial plasma bubbles from GPS-TEC data. Journal of Geophysical Research: Space Physics, 127, e2021JA029798. https://doi. org/10.1029/2021JA029798