Is there a one-to-one correspondence between ionospheric anomalies and large earthquakes along Longmenshan faults?

摘要

On 12 May 2008, a destructive M8.0 earthquake struck Wenchuan County(31.0° N, 103.4° E) in the Longmenshan fault zone ofsouthwestern China. Five years later, on 20 April 2013, another terrible M7.0earthquake struck Lushan County (30.3° N, 103.0° E) in thesame fault area, only 87 km away from the epicenter of the Wenchuanearthquake. In this paper, an integrated wavelet analysis methodology isproposed to detect and diagnose ionospheric total electron content (TEC)anomalies related to seismic activities. Analytic wavelet transform is usedto detect ionospheric perturbations, and then cross-wavelet analysis is usedto diagnose ionospheric anomalies by gaining further insights into thedynamic relationship between the anomaly variability of ionospheric TEC andgeomagnetic indices for the same set of observations. The results show that asignificant ionospheric disturbance occurred on 9 May 2008 above theforthcoming epicenter, 3 days prior to the Wenchuan earthquake. However, wedid not observe an ionospheric anomaly over the epicenter of the Ya'anearthquake during the 1 month period before the shock. Finally, we discussthe possible interpretations of the different seismo-ionospheric effects forthe two similar earthquakes.