Coordinator:  Dr. Mala Bagiya
Team Members: Dr. Shantanu Pandey, Dr. Rabin Das, Dr. Nongmaithem Menaka Chanu

Ionospheric Seismology and Volcanology (ISV): The concept of Lithosphere-Atmosphere-Ionosphere Coupling 

Ionospheric Seismology refers to the study of seismic events of earthquakes and tsunamis through coseismic ionospheric waves produced by the dynamic coupling between the Earth’s surface and the atmosphere. In recent times, Ionospheric seismology is becoming more of the use of ionospheric measurements for seismological purposes e.g. approximating the seismic fault dimension (Astafyeva, 2019).

Large earthquake (generally Mw > 6.5) produces vertical movement of the earth’s surface and excites atmospheric waves. Strong volcanic eruptions are also known to produce such waves. The excitation of waves occurs through mechanical/dynamic coupling between the earth’s surface and atmosphere. The excited waves are acoustic and internal gravity waves. These waves propagate to the ionosphere and produce electron density disturbances in the F-region typically after 10 -15 minutes of earthquake/volcanic eruption. 

Extensive research have been carried out in characterising the CIP excited by direct epicentral waves. The ionospheric measurements are further used for seismological purposes, such as rupture propagation direction, crustal deformation pattern and thrust orientations, based on the azimuthal distribution of CIP produced by direct epicentral waves (Bagiya et al. 2017; 2018; 2019). In recent times, efforts are being made to learn the contributions of suit of seismic sources, which successively rupture along the fault, in exciting near field CIP (e.g. Bagiya et al. 2020). 

In the case of CVIP, the findings are limited due to less frequent strong volcanic eruptions events and also lack of related ionospheric observations.  

This program aims to investigate various characteristics of CIP and CVIP to learn more on the application of ionospheric measurements for seismology and volcanology. 

References:
Astafyeva, E. (2019). Ionospheric detection of natural hazards. Reviews of Geophysics, 57, 1265–1288, https://doi.org/10.1029/2019RG000668. 

Bagiya, M. S., Sunil, A. S., Sunil, P. S., Sreejith, K. M., Rolland, L., & Ramesh, D. S. (2017). Efficiency of coseismic ionospheric perturbations in identifying crustal deformation pattern: Case study based on Mw7.3 May Nepal 2015 earthquake. Journal of Geophysical Research: Space Physics, 122, 6849–6857. https://doi.org/10.1002/2017JA024050.

Bagiya, M. S., Sunil, P. S., Sunil, A. S., & Ramesh, D. S. (2018). Coseismic contortion and coupled nocturnal ionospheric perturbations during 2016 Kaikoura, Mw7.8 New Zealand earthquake. Journal of Geophysical Research: Space Physics,123(2), 1477–1487. https://doi.org/10.1002/2017JA024584.

Mala S. Bagiya, A. S. Sunil, Lucie Rolland, Srinivas Nayak, M. Ponraj, Dhanya Thomas, and D. S. Ramesh (2019). Mapping the Impact of Non-Tectonic Forcing mechanisms on GNSS measured Coseismic Ionospheric Perturbations. Scientific Reports (Nature Publishing Group), 9, 18640, doi:10.1038/s41598-019-54354-0.

Mala S. Bagiya, Dhanya Thomas, Elvira Astafyeva, Quentin Bletery, Philippe Lognonné, and D. S. Ramesh (2020). The Ionospheric view of the 2011 Tohoku-Oki earthquake seismic source: the first 60 seconds of the rupture. Scientific Reports (Nature Publishing Group), 10:5232, https://doi.org/10.1038/s41598-020-61749-x. 

Contact details:
Name: Dr. Mala Bagiya
Email: mala[dot]bagiya[at]iigm[dot]res[dot]in