Effects in the Ionosphere after the Chilean Earthquake on February 27, 2010, According to Data of Ground-based Ionosondes

Abstract

The paper analyzes the measurement data of the critical frequency (foF2) of the regular ionospheric F2-layer at a number of ground based stations of the vertical sounding of the ionosphere in order to detect disturbances in the ionosphere that followed the earthquake with a magnitude of M = 8.8. The earthquake occurred in Chile on February 27, 2010 at 0634 UT at an epicentral distance of 335 km from its capital city of Santiago. It was found that at significant distances (over 5000 km) from the earthquake epicenter under a quiet geomagnetic conditions, wave disturbances are observed in the behavior of foF2, exceeding approximately two standard deviations from the background level for three hours, with the maximum relative deviation of 20%. The analysis shows that the characteristics of disturbances in the ionosphere correspond in time to the arrival of a packet of acoustic-gravity waves excited in the atmosphere at the time of the seismic shock.