Morgan and McGovern show in their computer models that volcanic material was able to spread to Olympus-sized proportions because of the clay's friction-reducing effect, a phenomenon also seen at volcanoes in Hawaii.
What may be trapped underneath is of great interest, said the researchers. Fluids embedded in an impermeable, pressurized layer of clay sediment would allow the kind of slipping motion that would account for Olympus Mons' spread-out northeast flank and they may still be there.
Thanks to NASA's Phoenix lander, which scratched through the surface to find ice underneath the red dust last year, scientists now know there's water on Mars. So Morgan and McGovern feel it's reasonable to suspect water may be trapped in pores in the sediment underneath the mountain.
"This deep reservoir, warmed by geothermal gradients and magmatic heat and protected from adverse surface conditions, would be a favored environment for the development and maintenance of thermophilic organisms," they wrote. This brings to mind the primal life forms found deep in Earth's oceans, thriving near geothermal vents.
Finding a source of heat will be a challenge, they admitted. "We'd love to have the answer to that question," said McGovern, noting evidence of methane on Mars is considered by some to be another marker for life. "Spacecraft up there have the capability to detect a thermal anomaly, like a magma flow or a volcano, and they haven't.
"What we need is 'ground truth' something reporting from the surface saying, 'Hey, there's a Marsquake,' or 'Hey, there's unusual emissions of gas.' Ultimately, we'd like to see a series of seismic stations so we can see what's moving around the planet."
|Contact: David Ruth|