Two-step method to extract seismic microwave radiation anomaly: Case study of M_S8.0 Wenchuan earthquake

The satellite remote sensing has become a promising technique for detecting earthquake and fault activities. But it is still very difficult to exactly extract the earthquake anomaly from the complicated remote sensing information. This paper presented a two-step method to extract the seismic microwave radiation anomaly related with earthquake, which could eliminate the stable influence of geography, terrain, coversphere and seasons, as well as the random influence of weather. Furthermore the two-step method was applied to analyze the anomaly of Wenchuan earthquake based on the data of AMSR-E. Microwave radiation anomalies were effectively detected related to the main shock and aftershocks. The extracted microwave radiation variation showed general features of three-stage: the positive radiation anomaly appeared around the epicenter in the first stage, quiet variation in the second stage, and abnormal area gradually moved to the epicenter in the third stage. After the main shock the microwave radiation anomalies distributed along the Longmenshan faults, and the epicenters of aftershocks were coincident with the anomaly area in space.