Transcurrent faults: oblique strategies

Last night I attended the monthly meeting of one of my local geological societies. The speaker, Gary Fuis of the US Geological Survey, presented his recent findings on the San Andreas fault in its central and southern segments. Various geophysical methods have shown that this classic strike-slip or transcurrent fault is not a vertical crack everywhere, but in some places has quite a shallow slope, as gentle as 37 degrees. (His abstract says as little as 10 degrees, but I didn't hear him state that number last night.) He went on to talk about the deep structure underneath the crust, but I was left boggling at those shallow dips. We all have the simple mental model of the vertical fault plane. Sure, I knew they actually slope a few degrees here and there, but the discrepancy from reality made my mind slip quite strikingly.