Seismic Characteristics of Strong Deep Focal Earthquakes and Associated Phenomena in Northeastern Asia
In Northeastern Asia, strong deep focal earthquakes (MS 5.8, generally focal depths > 430 km) distribute approximately north-south trending, which is very similar to the trend of the slab structure. From 1900, temporal distribution of strong deep focal earthquakes is non-stationary. Based on the wavelet transform, relative active and quiet periods are divided. Each active or quiet period is about 12 years. In terms of energy index (square root of energy released by earthquakes), in total about 79% of strong deep focal earthquakes occurred in active periods. For strong shallow earthquakes in Northeastern Asia, seismic characteristics in the eastern part are different from that in the western part. Temporal distribution of strong shallow earthquakes in the eastern part is very similar to that of strong deep focal. The results of the territorial limit test show that in the eastern part of 120°E, the ratios of energy index in active periods are stable in high level. In the western part of 117°E, the ratios are stable in low level. There is a transition belt between 117°E and 120°E. The north-south trending Tan-Lu fault is an important boundary. The strong deep focal earthquakes have a correlation with shallow earthquakes in Northeastern Asia. The relationship cannot be understood as an accidental event. The mechanism of the relationship is analyzed. The mantle convection and its attenuation take important role.
Advances in Geosciences, Volume 9: Solid Earth, Ocean Science & Atmospheric Science (2006)
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