A pyroclastic flow (also known scientifically as a pyroclastic density current) is a fast-moving current of hot gas and rock (collectively known as tephra), which reaches speeds moving away from a volcano of up to 700 km/h (450 mph).The gas can reach temperatures of about 1,000 Â°C (1,830 Â°F).Pyroclastic flows normally hug the ground and travel downhill, or spread laterally under gravity. Their speed depends upon the density of the current, the volcanic output rate, and the gradient of the slope.They are a common and devastating result of certain explosive volcanic eruptions.yroclastic flows normally hug the ground and travel downhill, or spread laterally under gravity. Their speed depends upon the density of the current, the volcanic output rate, and the gradient of the slope.
Optimal Reading. An optimal reading is considered anything lower than 120/80. The actual number of 120/80 is not considered perfect--but actually numbers lower are considered to be optimal. For example, someone with a blood pressure reading of 116/76 has an optimal reading.ptimal Reading. An optimal reading is considered anything lower than 120/80. The actual number of 120/80 is not considered perfect--but actually numbers lower are considered to be optimal. For example, someone with a blood pressure reading of 116/76 has an optimal reading.
Cant be right Tent Maybe you mean 80 / 40 All of our blood pressure levels vary day by day and over the course of a day. Assuming you don't feel any different from normal then it should be nothing to be too concerned about.Low blood pressure (which 80/40 is) can either be a normal thing for you or a reflection of an underlying health problem-maybe the latter in your case if you have a nurse checking it.Ask your nurse for more information Good video about blood pressure readings here http://www.youtube.com/watch?v=EvpoPNoOt...est Answer: Low blood pressure usually are not dangerous unless too low. If you got 80/40 only once and all other times are 60-70/90-100, then probably ok.