Typical Precursor Anomalies of the February 6, 2023, Mw 7.8 and Mw 7.6 Kahramanmaraş Earthquake Doublet, Turkey, and the Mw 9.0+ Andaman-Sumatra and Tohoku, Japan Mega-Earthquakes

Abstract—Previously, based on the construction and analysis of the generalized vicinity of a large earthquake (GVLE), the set of typical precursor signs of a large earthquake was identified and described in great detail. However, these typical features are rather rarely detected in the foreshock areas of individual large earthquakes. It was noted that the proportion of the events occurring in the foreshock regions where precursor signs are identified increases with the number of weak events in the vicinity of a given large earthquake. In this paper, a number of cases provided with more extensive seismicity data, it is checked how often the GVLE signs are detected when large sets of seismological data are considered. It is shown that in these cases, GVLE anomalies are detected in most cases. A proportion between the magnitudes of the target events and the completeness level of the catalogs to ensure highly probable identification of precursor GVLE anomalies is proposed. The problem of false alarms remains unresolved.