Abstract:
The lithosphere and the atmosphere/ionosphere, continuously exchange energy through
various coupling mechanisms. Earthquake creates waves of energy, e.g. direct shock
acoustic waves (SAWs) and Rayleigh wave induced acoustic waves (RAWs). In the event of
an earthquake occurring beneath the sea, atmospheric gravity waves (AGWs) are also
generated. If the earthquake is large enough (Mw > 6), SAWs, RAWs and AGWs induce
detectable ionospheric plasma perturbations. Inferring the seismological information from
these seismo-ionospheric manifestations is the subject that pertains to ionospheric seismology.
Both ground and satellite based advanced radio techniques are being used in
monitoring ionospheric plasma perturbations. In this study, seismo-ionospheric anomalies
and implications from recent GNSS observations in India and South-East Asia are discussed,
mainly pertaining to the following. (1) From the ionospheric plasma response to
2015 Nepal earthquake, the estimated group velocity for Andaman and Indian shield regions
are 2100 ms 1 and 3900 ms 1 respectively and validated from ground measurements.
(2) Atmospheric acoustic resonance at 4.0 mHz and a train of wave packet of TEC variation
resulting from the beat phenomenon observed at the site ‘umlh’ and (3) GNSS-based
tsunami warning which is going to be promising tool in augmenting the existing tsunami
warning systems.
