Contribution of Rifting Activities to Spatial and Temporal Variations of Seismic B-Values Along the Gulf of Aden Area, Case Study

This paper presents a valuable link between the influence of seismic b-values and the rifting activities offshore of Gulf of Aden area combining with spatial and temporal variation. The study area is classified into three major seismic periods according to the number of events recorded. The first period is characterized by relatively high average b-values (0.95) due to shallow earthquake events. In the second period, there is a rapid decrease in b-values (0.83) starting from 1991. This is likely attributed to the increase in the global seismic moment release in the same year. The last seismic Period showcases the highest earthquake magnitude ever recorded indicating low- to moderate b-values near the study area. For the spatial variation, low b- values are also observed in the eastern side of the Gulf of Aden's spreading ridge. A valid interpretation for this observation is the remarkable increase in stress level conditions that are formed before or during medium-large earthquake events, while aftershocks are associated with high b-values since the stress level decreased. Major transform faults and normal faults on the eastern side contribute to major discontinuities and rifting zones along the ridge and play a key factor behind the high stress conditions.