摘要：Vrancea intermediate-depth earthquakes with a depth range of 60–160 km occur frequently.By using data from ROMPLUS catalog, we analyze earthquakes with M ≥ 7.0 that occurred during 1500–2000.We propose a periodic upward migration (PUM) model for these earthquakes.According to this model, (1) active zones at the bottom of seismic regions migrate upward with the velocity V , with the activity starting from the year T S and, (2) this migration repeats every T P years, and at a given depth, seismic active period continues for T 1 years.We test the model using the likelihood function and compare the model with a uniform Poisson model.A simulation using the bootstrap method indicates that the PUM model for M ≥ 7.5 and M ≥ 7.3 earthquakes is statistically significant at the 5% level and is better than the Poisson model.We propose the following regularity for Vrancea M 7 intermediate-depth earthquakes.Three earthquakes occur at a depth of 140–160 km, 110–140 km, and 80–110 km at the beginning, at the middle, and at the end of each century, respectively.This phenomenon repeats every century.The next M 7 earthquake is expected to occur at a depth of 140–160 km soon.
关键词：Intermediate-depth earthquake ;Vrancea earthquake ;earthquake prediction ;likelihood function ;migration
