In the centre of a pumice-covered plateau from loon to 2000 ft. In 1886 there was a serious volcanic eruption in the outlying island of Nivafoou, and at the same time Falcon Reef, normally awash at high water, discharged sufficient scoriae and pumice to form a new island 50 ft.
The superior facet, also called the superior articular process, is a pair of facet joints between pairs of vertebrae. A facet joint is what holds two vertebrae together and each vertebra contains two pairs, an upper-facing superior facet pair and a lower-facing inferior facet pair.
The facet joints glide and allow the spine to move freely with support. Facet arthrosis is degeneration or wear and tear of the facet joints. Severe facet arthrosis would be advanced degeneration, possibly with arthritis or bone spurs. This might cause pain, and/or cause stiffening of the spine, and/or even put pressure on the spinal nerves or thecal sac (which contains the spinal cord). I've put more information in the links below.