Remote Sensing of Atmospheric CO and O3 Anomalies before and after Two Yutian MS7.3 Earthquakes

Satellite remote sensing data were used to extract concentrations and volume mixing ratios (VMR) of CO and O-3 and Global Data Assimilation System (GDAS) data associated with Yutian M(S)7.3 earthquakes on March 21, 2008, and February 12, 2014. Difference value and anomaly index methods and the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model were used to simulate gas backward trajectories and analyze the relations between spatial and temporal variations in total columns of CO and O-3 (TotCO and TotO(3)) and earthquakes. Then, the causes of abnormal changes were examined. Maximum anomalies in TotCO and TotO(3) occurred one month before the 2008 earthquake and one month after the 2014 earthquake. Anomalies in TotCO and TotO(3) were distributed along or were consistent with the fault zone. Furthermore, during the abnormal period, the coefficient of correlation between CO and O-3 was 0.672 in 2008 and 0.638 in 2014, with both values significant at p<0.05. The correlation between TotCO and TotO(3) was also significant. The abnormal phenomena of TotCO and TotO(3) associated with the two earthquakes were attributed to underground gas escape, atmospheric chemical reactions, and atmospheric transportation caused by in situ stress in the generation of earthquakes.