Electromagnetic Anomalies around Wenchuan Earthquake and Their Relationship with Earthquake Preparation

Electromagnetic precursors before Wenchuan earthquake on May 12, 2008, were collected and summarized on the basis of related published papers. The relationship was analyzed between electromagnetic anomalies and different earthquake preparation stage, and an entire seismic preparation process was constructed according to corresponding anomalies in different electromagnetic parameters. Stereo electromagnetic observation is useful in earthquake study. However there are still a lot of questions in anomaly distinguishing and coupling mechanism, which are discussed finally.