Recent studies have shown that earthquake-associated total electron content (TEC) anomalies are detectable using principal component analysis (PCA) regardless of other possible causes of TEC disturbance such as TEC long term variance, solar flare and geomagnetic storm activity. PCA is an alternative pure mathematical method for the measuring TEC anomalies. PCA applied to both pre-earthquake and post earthquake TEC has been able to detect and even describe the physical shape of earthquake associated TEC anomalies. In this Book, Two-|Dimensional Principal Component analysis (2DPCA) is used to detect the ionospheric TEC anomaly relating to very deep earthquake