AUTHOR=Bhardwaj Arti , Gupta Ankit , Ahmed Qadeer , Singh Anshul , Gupta Sumedha , Sarkhel S. , Sunil Krishna M. V. , Pallamraju Duggirala , Pant Tarun , Upadhayaya A. K. 

TITLE=Signature of Y-forking in ionogram traces observed at low-mid latitude Indian station, New Delhi, during the earthquake events of 2020: ionosonde observations

JOURNAL=Frontiers in Astronomy and Space Sciences

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/astronomy-and-space-sciences/articles/10.3389/fspas.2023.1170288

DOI=10.3389/fspas.2023.1170288

ISSN=2296-987X

ABSTRACT=<p>We have examined ionospheric response to eleven earthquake events measuring less than four on the Richter scale during the year 2020 that occurred in the vicinity of New Delhi (28.6°N, 77.2°E, 42.4°N dip). We have used ionogram traces, manually scaled critical ionospheric layer parameters using SAO explorer obtained from Digisonde along with the O(<sup>1</sup>D) airglow observations from a multi-wavelength all-sky airglow imager installed at Hanle, Ladakh, India (32.7°N, 78.9°E, 24.1°N dip). Perceptible ionospheric perturbations 2–9 days prior to these earthquake events resulting in more than 250% variation in electron density are observed. We found distortion of ionogram trace in the form of Y forking majorly at New Delhi on the precursor day and after the earthquake event. Traces of Y forked ionograms were also observed at Ahmedabad (23°N, 72°E, 15°N dip) and Trivandrum (8.5°N, 76.9°E, 0.5°N dip). These Y-forked ionograms are one of the first observations during any earthquake events and are looked at as a signature of Travelling Ionospheric Disturbances (TIDs).</p>