How to Read the Display. The seismograms displayed are from a few of the seismograph stations routinely recorded by the Northern California Seismograph Network. Each is a record of how the ground moved at a particular seismograph station in Northern California during a 24-hour period.he height of the recorded waves on the seismogram (wave amplitude) is a greatly magnified representation of the actual ground motion. A recording of an earthquake has recognizable characteristics.
View Full Profile. There are three main causes of retinal detachment, each with its own set of risk factors. The most common type is called a ârhegmatogenousâ detachment, and is caused by a tear or hole in the retina. The retina is the thin, light-sensitive tissue that lines the back inside wall of the eye.
A sudden blow to the head or eye, such as hitting a windshield or having an air bag deploy, can also create a tear in the retina. Head trauma is also among the most common causes of retinal detachment in children. Other risk factors for rhegmatogenous detachments include a family history of retinal detachment and certain congenital or hereditary eye diseases. A less common type of retinal detachment is called a âtractionalâ detachment. This occurs when vitreous tugs on the retina over time, gradually causing the retina to tent up off the back of the eye. Tractional detachments do not occur suddenly and are not associated with retinal tears.