Articles | Volume 13, issue 9
Nat. Hazards Earth Syst. Sci., 13, 2331–2336, 2013
Nat. Hazards Earth Syst. Sci., 13, 2331–2336, 2013

Research article 24 Sep 2013

Research article | 24 Sep 2013

Sub-ionospheric very low frequency perturbations associated with the 12 May 2008 M = 7.9 Wenchuan earthquake

A. K. Maurya1, R. Singh1, B. Veenadhari2, S. Kumar3, and A. K. Singh4 A. K. Maurya et al.
  • 1KSK Geomagnetic Research Laboratory, IIG, Chamanganj, Allahabad, India
  • 2Indian Institute of Geomagnetism (IIG), New Panvel, Navi Mumbai, India
  • 3School of Engineering and Physics, The University of the South Pacific, Suva, Fiji
  • 4Physics Department, Banaras Hindu University, Varanasi, India

Abstract. The present study reports the VLF (very low frequency) sub-ionospheric perturbations observed on transmitter JJI (22.1 kHz), Japan, received at the Indian low-latitude station, Allahabad ( geographic lat. 25.41° N, long 81.93° E), due to Wenchuan earthquake (EQ) that occurred on 12 May 2008 with the magnitude 7.9 and at the depth of 19 km in Sichuan province of Southwest China, located at 31.0° N, 103.4° E. The nighttime amplitude fluctuation analysis gives a significant increase in fluctuation and dispersion two days before EQ, when it crosses 2σ criterion. However, there was no significant change observed in the amplitude trend. The diurnal amplitude variation shows a significant increase in the amplitude of JJI signal on 11 and 12 May 2008. The gravity wave channel and changes in the electric field associated with this EQ seem to be the potential factors of the observed nighttime amplitude fluctuation, dispersion, and significant increase in the signal strength.