Mapping emission of carbon-bearing gases from the satellite hyperspectral data in western Sichuan before and after the 2008 Wenchuan M_S8.0 earthquake

Carbon-bearing gases underground strongly emitted before and after the M_S8.0 Wenchuan earthquake in 2008. This paper obtained the temporal and spatial distribution characteristics of carbon-bearing gases anomalies by using the differential method with the satellite hyperspectral data. The data showed that CO₂, CH₄ and CO anomalies occurred before and after Wenchuan earthquake, which were spatially controlled by the faults obviously and were similar with the thermal infrared anomaly distribution. CO and CO₂ anomalies had a larger range than CH₄. CO anomaly distributed not only along the Longmenshan fault but also in the Sichuan basin. The order of carbon-gas anomaly appearance was CO₂, CH₄ and CO. CO₂ and CH₄ gases mainly emitted from the inner earth along the Longmenshan fault, and CH₄ also may be the reduction products of CO₂ under the reduce condition. CO can be controlled not only by the gas emission along the fault but also by the emitted CH₄ oxidation, and CO anomaly in the Sichuan basin was caused by the oxidation of CH₄ which seepes from the oil and gas field. The results not only provide new monitoring parameters of earthquake precursor but also a scientific basis for the mechanism of thermal infrared anomaly associated with “earth degassing and greenhouse effect”，and can be used in the study of earthquake prediction. At the same time, the results play an important role in the study of geological carbon-emission caused by earthquake.