kingwinner Posted October 5, 2005 Report Share Posted October 5, 2005 1)According to the definition of the Wadati-Benioff Zone, earthquakes can have a focus no deeper than 670km below the surface of the earth because beyond a depth of 670km, the rocks are able to deform without breaking (ductile deformation), i.e. bend or flow easily without breaking! WHY? (I thought only the asthenosphere is behaving this way!) 670km deep is far below the asthenosphere layer...why are earthquakes able to occur in the asthenosphere (about 70-250km deep) but never below a depth of 670km which is part of the rigid upper mantle? 2) The following figure is showing the San Andread Fault, with Pacific plate on the left and North American plate on the right! There are 2 small arrows pointing correctly along the fault! But I am wondering if the 2 big arrows are pointing in the wrong direction...should both arrows be pointing the other way around, ie same as the small arrows? (I remember seeing a map showing that the Pacific plate moves northwest realtive to North American plate, or does my memory serves me wrong?) Can somebody take a look and explain it to me, please? :hyper: Quote Link to comment Share on other sites More sharing options...
kingwinner Posted October 5, 2005 Author Report Share Posted October 5, 2005 repied in the wrong post...please delete this reply! Quote Link to comment Share on other sites More sharing options...
kingwinner Posted October 10, 2005 Author Report Share Posted October 10, 2005 Can somebody explain please? I still can't figure it out... Quote Link to comment Share on other sites More sharing options...
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