 Around the caldera lie 40 lava domes , which extend northwest @-@ southeast . There is an eastern group between Monte Pissis and Cerro Bonete Chico and a western one on the Sierra de Veladero . Overall , the domes have heights of 100 – 600 metres ( 330 – 1 @,@ 970 ft ) and a basal apron of about 1 kilometre ( 0 @.@ 62 mi ) width of erosional material . Some domes have water @-@ filled craters with widths of 20 metres ( 66 ft ) at their top . Domes on the caldera 's northern side are dacitic and show signs of alteration . Some domes are probably part of the pre @-@ caldera complex , and several rhyodacitic domes were modified by erosional processes after caldera formation ; these were formerly considered erosional remnants . Older domes have reddish oxidized colours in satellite images . The total volume of the domes is about 16 cubic kilometres ( 3 @.@ 8 cu mi ) . 
