Wave-like perturbations in the ionospheric F2-layer observed after the Ms8.1 Samoa earthquake of September 29, 2009 Original Research Article

A study of the critical frequency foF2 variations after the large earthquake (Ms = 8.1) which occurred on 29 September, 2009 in the region of Samoa Islands in the Pacific Ocean is carried out using data of the ionospheric station of Kwajalein. The epicenter of the earthquake was located at about 184 km southwest from Apia (the capital of West Samoa). It was found that wave-like perturbations of foF2 were observed for ∼3 h above the station (located approximately 3560 km northwest from the epicenter). The amplitude of the disturbance was as large as ∼20% of the average magnetic quiet day foF2 values. A comparison of the observed perturbations of foF2 with the ones detected at Stanford ionospheric station after the Alaska earthquake of 28 March 1964 (Ms = 8.4) showed a close similarity of the wave-like perturbations of foF2 in both cases.