High viscosity "lava"
http://themis.la.asu.edu/zoom-20020718a.html
Note the rebound peak in the north crater - the flow out of these Martian "volcanos" has to be some kind of "pyroclastic" mud, and not lava, as we've been told so many times before.
That said, any idea why the faults occur where they do?
On Earth oil deposits sometimes accumulate in the pressure ridges created by large impacts - but given the Martian lithosphere, could such deep fractures occur? Or would the shock wave simply travel, and given a large enough impact, then simply collide with itself, leading to surface eruptions?
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