The crater on the rim of Victoria crater on the right side of this
image very definitely gives the impression of a volcanic crater rather
than an impact crater:
Victoria Crater on Mars.
http://antwrp.gsfc.nasa.gov/apod/ap061002.html
An analogue of the Victoria crater complex might be Crater Lake,
Oregon:

Crater Lake, Oregon
Crater Lake National Park
http://vulcan.wr.usgs.gov/Volcanoes/...framework.html

A curious aspect of Victoria crater is its irregular rim with
alternating promontories and alcoves. The rim of Crater Lake, Oregon
might be analogous to this:

Crater Lake, Oregon.
http://earthobservatory.nasa.gov/New...3?img_id=17401

Although in the case of Crater Lake, the irregular rim is only
apparent on half of the rim, the other half having a more rounded
appearance.
The volcanic crater on the rim of Victoria might be analogous to
Wizard Island and Mount Scott in the Crater Lake complex, labeled in
the preceding image.
The crater forming Crater Lake formed from the collapse of a volcano.
Then an analogous scenario would account for the origin of Victoria
crater on Mars. Then Victoria itself might be a volcanic crater.
Then these two craters might give us a chance for the first time to
observe the interior of a volcanic crater on Mars.


Bob Clark