The Planets around Tau Ceti may be fairly volcanic

[radtech497]

If it is a "hot ice giant" (or, rather, a "hot ice dwarf"), then it might be similar to a miniature HydroJovian; if a waterworld, then it might even be of the BathyPelagic type, because of its (relatively) low mass. The low metallicity of the primary star (~28% relative to Sol) indicates most, if not all, planets will be rocky terrestrials rather than gas giants, so the likelihood of e being a gas dwarf is not high. A large terrestrial or a waterworld seem the most probable choices, in that order. As far as warmth is concerned, quantities of liquid water will persist on the surface at (Bond) albedos between 0.278 and 0.343, assuming Earth-like atmospheric pressures and constituents.

Radtech497

[stevebowers]

Reading the entry for Nova Terra a bit more closely, I note that the planet is described as prone to earthquakes, especially in the developing rift valley near the centre of the continent Hope. This continent will probably split up in the next hundred million years or less.

[iancampbell]

Nova Terra appears to be the planet now known as tau Ceti e, though its semi-major axis is 41.3% farther from tau Ceti and is 25.75% as massive. While Nova Terra can be explained away as a small world somehow missed by earlier surveys, this seems a bit contrived. It might be better, IMO, to retcon Nova Terra to the confirmed tau Ceti e, with the following characteristics:

Mass: 4.3 x Earth, radius: 9749 km, distance from primary: 0.552 A.U., gravity: 1.84 g, and Year: 0.464 Earth year (213.29 Nova-days), with the other entries in the data panel staying the same.

As for a high rate of plate tectonics and volcanism on Nova Terra, volcanoes are generally are located along and beside plate boundaries, whereas orogenic uplifts (folding of rock strata upwards to form mountains) typically occurs farther from those boundaries. If, as is proposed, magmatic viscosity is reduced in planets orbiting magnesium-enriched stars like tau Ceti, the main effects would be an increased rate of plate travel and a corresponding increase in the rate of emergence of "hotspot" volcanoes. Increased volcanism leads to increased emissions of sulfur oxides, carbon dioxide, and water vapor, which may, in turn, lead to increased atmospheric warming (which would be at least partly offset by the cooling effects of sulfur aerosols).

Just a few notions,

Radtech497

I believe that on Earth, volcanoes occur in three types of location. One is on top of a magma plume (example: Hawaii); another is at plate boundaries where the plates are being pulled apart (all the mid-oceanic ridges, IIRC, particularly the Atlantic one, plus the African Rift Valley); and the third is destructive plate boundaries, examples being the Pacific Ring of Fire.

AFAIK, volcanoes do not occur (although earthquakes certainly do) at plate boundaries where two areas of continental crust are colliding with one another. Modern examples of this are the Alps and the Himalayas.

I believe it's also thought that water has a lot to do with tectonic activity. This is because magma containing significant amounts of water is much more fluid than without, and destructive plate boundaries where ocean bottoms are diving under a continent are obviously going to have lots of water.

Lastly, the thickness of the crust is also relevant. Earth has a much thinner crust than Venus, probably because of the impact that formed the Moon. And Venus has relatively few volcanoes, and the ones that it does have are very different from Earth's - much larger, for a start.