Editing HarnWorld:Main Page (section)

==Kethira: Tectonics & Vulcanism==
Kethira has a nickel-iron core kept solid by immense pressure. Around this is an outer core of the same composition, but liquid. The bulk of the planet is a mantle of various compressed iron-magnesium silicates which are fairly rigid to a depth of about 720 kilometers. The outermost layer of the mantle is a crust, rocks formed from gradual cooling, which has fractured into a number of large plates.

The fact that the surface plates are floating on a semi-liquid mantel does not result in a particularly stable situation. The plates drift slowly across the surface. Where they rub against each other the friction causes earthquakes. Where they are moving apart, the molten rocks of the interior exude in volcanic eruptions. Where an oceanic plate slides under a continental plate, the upheaval creates a mountain range along the discontinuity, and a deep oceanic trench offshore.

The picture is more complicated than this however. The plates are not of uniform thickness or consistency. Isolated hotspots exist where the plates are thin or perforated, resulting in solated volcanic activity and local hot springs. Some plates are "softer" than others. The Azeryan-Karenjia plate, for example, is in the process of being broken apart by the larger and firmer plates to the east and west. Complex warping dictates that this part of the planet has more than its share of natural disasters. The eastern part of the East Lythia plate is also soft and will eventually be crushed. All such effects exist in varying degrees on Kethira.

All these motions are, of course, very slow. The residents of Azeryan and Karejiacan hardly notice the drift of continents. All they can perceive is that from time to time, the local conical mountain erupts, or the earth beneath them quakes, causing great hardship.

[[HarnWorld:Tectonics|Vulcanism & Tectonics Map]]