Pre-earthquake Prediction Method Based on Electromagnetic Wave Abnormal Signal Detection

Earthquakes will pose a threat to people’s lives and property. At present, only a large number of monitoring stations can be used to predict the earthquake information that has occurred. In the pre-earthquake period, before the rocks beneath the ground squeeze each other without dislocation, abnormal electromagnetic waves will be generated due to the piezomagnetic effect. Abnormal electromagnetic waves belong to weak electromagnetic radiation, so it is difficult to detect and identify the spectrum energy quickly and accurately. The I/Q signal contains all electromagnetic wave information. This paper proposes a method for detecting abnormal electromagnetic waves in the pre-earthquake period based on the distribution characteristics of the original I/Q data. We collect the I/Q sample data of the target frequency band, divide the distribution of the samples according to the I/Q components, and calculate the cumulative I/Q distance of each I/Q component to the origin. According to the algorithm to detect the fluctuation of the cumulative I/Q distance, the abnormal electromagnetic interference caused by the piezomagnetic effect in the early period of the earthquake is identified. Combined with the official earthquake broadcast data, if the monitoring location is not disturbed by abnormal electromagnetic waves, the I/Q distance will fluctuate in a certain pattern over time. When receiving abnormal electromagnetic wave interference, the envelope of I/Q distance fluctuation will change like a convex function. This paper proposes a sliding window extreme value method to estimate the fluctuation trend of I/Q distance. We propose a secondary sliding window extreme value method to estimate the position of the inflection point of the I/Q distance fluctuation, which is the time point of interference by abnormal electromagnetic waves. The experimental results can show that the I/Q distance fluctuation detection and recognition can effectively detect the abnormal electromagnetic wave changes in the pre-earthquake period. In the future, it is considered to increase the number of space monitoring nodes and study the direction and position estimation model of abnormal electromagnetic waves.