Who can explain to me why the slope of Olympus Mons is so low?

Question

It seems to me that, in the lower Martian gravity, steeper slopes would be expected, a steeper angle of repose. This has puzzled me for a long time, so I thought I'd see if anyone knows.

Answer 1

i saw this on discovery channel  .. from landslides due to moonquakes

Answer 2

Olympus Mons is indeed a shield volcano, but the gradual slope has little to do with differences in gravity between earth and Mars.  The reason Olympus Mons has such a gradual slope is because of the heat of the lava produced.  Shield volcanoes on earth emit basaltic lava that is as thin and runny as water when erupted, so it spreads out as much as it can as fast as it can forming the shield shape.

At the other extreme is the dacite lava emitted by Mt. St. Helens during its latest eruption which is much cooler and is more like taffy.  The cooler dacite lava piles up like the domes in Mt. St. Helens' crater, while the hot basalt from Kilauea runs for miles, clear to the sea before pouring into the water.

Answer 3

Agree with it or not, eelfins gave you the correct answer. Compare Mauna Loa in Hawaii(a shield volcano) to Mt. St. Helens (a composite volcano). Olympus Mons is a shield volcano.

Answer 4

Perhaps just the massive size.

Also there is atmosphere which may help sculpt and erode a bit.  Also magma might be very hot and spread too much before cooling and solidifying.

Answer 5

Olympus mons is a shield volcano, in which underground pressure does not build up enough to create a steep slope because magma is released regularly.