INTERMEDIATE TERM EARTHQUAKE PREDICTION BASED ON INTEREVENT TIMES OF MAINSHOCKS AND ON SEISMIC TRIGGERING
Two models, which contribute to the knowledge on intermediate term earthquake prediction are further examined, improved and applied. The first of these models, called Time and Magnitude Predictable (TIMAP) regional model is based on repeat times of mainshocks generated by tectonic loading on a network of faults which are located in a certain seismic region (faults’ region). The second model, called Decelerating-Accelerating Strain (D-AS) model, is based on triggering of a mainshock by its preshocks. Parameters of the TIMAP model have been specified for the Aegean area and applied by a backward test in 86 circular faults’ regions of this area. The test shows the validity of this time dependent model with 29% false alarms. Data concerning decelerating and accelerating seismic (Benioff) strain, which preceded 46 strong (M≥6.3) recent mainshocks in a variety of global seismotectonic regimes, show that the generation of a mainshock is triggered by quasi-static stress changes due to accelerating preshocks which occur in a broad (critical) region and by static stress changes due to the large number (frequency of occurrence) of small preshocks generated in a narrow (seismogenic) region. Retrospective predictions (postdictions) of these 46 mainshocks by the D–AS model confirms previous results concerning the prediction uncertainties (2σ) of the model in the origin time (± 2.5 years), epicenter location (≤ 150 km) and magnitude (± 0.4) of an ensuing mainshock with a probability ~ 80%. Information is also given on the successful prediction by the D-AS model of: 1) the Cythera strong (M = 6.9) earthquake which occurred on 8 January 2006 in the southwestern part of the Hellenic Arc and 2) of the Rhodes strong (M = 6.4) earthquake which occurred on 15 July 2008 in the Eastern part of this Arc. A backward combined application of both models in the Aegean area shows an uncertainty ≤120km in the epicenter location of an ensuing mainshock.