what is the importance of the wadati-benioff zone? Why don’t earthquakes happen below the zone (below 700km)?
I understand that a lot of deep earthquakes happen in the wadati-benioff zone but don’t understand why they dont’ occur beyond this zone. what is the ultimate importance of this zone? thanks!
The upper mantle transitions to the lower mantle at depths of 670 km to 700 km. Above this level, the mantle is relatively solid, although increasingly plastic as depth increases. Below this level the mantle behaves more like an extremely high viscosity liquid, and cannot support the buildup of stress necessary to produce earthquakes.