Research studies have recently illustrated a plausible relationship between seismic activity and ionospheric disturbances. To elucidate seismo-ionospheric disturbances, we analyzed the temporal and spatial characteristics of ionospheric disturbances associated with large earthquakes that occurred in North America. We selected two strong events with M ≥ 6.5 that took place in 2009 and 2010 during the solar minimum. We used the United States total electron content (US-TEC) measurements as a main dataset, and the changes in the TEC were compared with the variations in the topside plasma density measured by the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite. Positive or negative TEC anomalies were observed before (as a precursor) and after the earthquakes. In addition, we found that positive anomalies occurred more frequently than negative ones. Although TEC anomalies occurred at all local times, strong anomalies usually appeared from late afternoon to dawn (16–6 local time). Seismic activity-related TEC anomalies were typically limited to the earthquake region, whereas geomagnetic activity-related TEC anomalies were observed over a vast region. Furthermore, local TEC anomalies occurred over a long period of 20 days preceding and succeeding the earthquakes, in contrast to those associated with geomagnetic activities which occurred concurrently with the geomagnetic disturbances. Additionally, most abnormal increments in the electron density obtained by the DEMETER satellite over the seismic zone coincided with the TEC anomalies. Thus, the variations observed in the TEC and topside electron density before and after these two earthquakes suggest that these ionospheric disturbances are related to seismic activities.

最近的研究表明，地震活动与电离层扰动之间存在一种似是而非的关系。为了阐明地震电离层扰动，我们分析了与北美发生的大地震相关的电离层扰动的时空特征。我们选了两个有M的强赛事 ≥ 6.5 发生在 2009 年和 2010 年太阳活动极小期期间。我们使用美国总电子含量 (US-TEC) 测量值作为主要数据集，并将 TEC 的变化与通过地震区传输的电磁辐射检测 (DEMETER) 测量的上部等离子体密度的变化进行比较) 卫星。在地震之前（作为前兆）和地震之后观察到正或负的 TEC 异常。此外，我们发现正异常发生的频率高于负异常。尽管 TEC 异常在所有当地时间都有发生，但强烈的异常通常出现在下午晚些时候到黎明（当地时间 16-6 点）。与地震活动相关的 TEC 异常通常仅限于地震区域，而与地磁活动相关的 TEC 异常则在广大地区被观察到。此外，与与地磁扰动同时发生的地磁活动相关的异常相比，局部 TEC 异常发生在地震前后 20 天的长时间内。此外，DEMETER 卫星在地震带上获得的电子密度的大多数异常增量与 TEC 异常一致。因此，在这两次地震前后观察到的 TEC 和上层电子密度的变化表明这些电离层扰动与地震活动有关。DEMETER 卫星在地震带上获得的电子密度的大多数异常增量与 TEC 异常一致。因此，在这两次地震前后观察到的 TEC 和上层电子密度的变化表明这些电离层扰动与地震活动有关。DEMETER 卫星在地震带上获得的电子密度的大多数异常增量与 TEC 异常一致。因此，在这两次地震前后观察到的 TEC 和上层电子密度的变化表明这些电离层扰动与地震活动有关。