Study of infrasonic waves at low latitude northern hemisphere, India

62-66The infrasonic waves have been studied at the low latitude station Tirunelveli (8.7°N,77.8°E), India, in northern hemisphere. Almost 50 events of the severe earthquake (Ms > 6.0) have been studied. The changes in surface pressure as well as acoustic waves produced have been recorded immediately after the earthquake. The Rayleigh waves-induced changes in surface pressure which cause significant changes in pressure have been recorded by all the systems. The arrival of acoustic waves followed by large decrease in pressure has also been recorded in almost all the cases. Only a few cases have been reported. The infrasonic waves between 10 and 100 s have been observed. The infrasonic waves produced from the unknown sources have also been observed. But their variation feature is different from the earthquake-induced infrasonic waves. The corresponding microbaroms obtained at this station show variation similar to the infrasonic waves