Spatio-temporal revolution characteristics of methane emission before and after the 2013 Lushan M_S7.0 earthquake

Taking the case of Lushan M_S7.0 earthquake, the spatio-temporal evolution characteristics of methane (CH₄) before and after the earthquake were studied using CH₄ data got from atmospheric infrared sounder (AIRS) instrument on AQUA satellite. Total volume of CH₄, CH₄ vertical profiles and long-time serial variation before and after the earthquake were analyzed by the background contents difference value method. The results showed that the CH₄ concentration increased significantly in the epicentral area from January to April, 2013. The evolution trend of CH₄ appeared as following: initially rose→increased abruptly and diffused→accumulated and reached to maximum→relatively attenuated→degassed after earthquake→returned to normal. The anomalies of CH₄ concentration observed before the earthquake have reached the maximum in epicentral area during the period from January 2008 to August 2016. The increase of CH₄ concentration before the earthquake was likely to be the precursor of M_S7.0 Lushan earthquake.