Precursory effects in the nighttime VLF signal amplitude for the 18th January, 2011 Pakistan earthquake

• DOI: 10.1007/s12648-012-0014-5
• Publication Date: 2012-03-12T14:30:04Z
• Authors: S. Ray; S. K. Chakrabarti; S. Sasmal
• Keywords: Longitude; Low latitude; SIGNAL (programming language)

We have presented the result of the analysis of the nighttime VLF signals transmitted from the Indian Navy station VTX (latitude 8.43°N, longitude 77.73°E) at 19.2 kHz and received at Kolkata (latitude 22.57°N, longitude 88.24°E). On 18th January, 2011 an earthquake of magnitude 7.4 occurred at Southwestern Pakistan (latitude 28.9°N, longitude 64°E). We have analyzed the nighttime VLF signals for 2 weeks around 18th of January, 2011 to see if there have been any precursory effects of this earthquake. We have found that the amplitude of the nighttime VLF signals anomalously fluctuated 4 days before the earthquake. This agrees well with our previous findings based on the analysis of 1 year of earthquake data.