What is the meaning of precise leveling in volcano monitoring?
435714
From what I understand, precise levelling is important in tilt monitors so that they can monitor very fine movements in the pitch of the ground which would follow magma influx into a near-surface body.  Usually there are near-vent tilt monitors and far-field monitors, one measures movement of magma near the neck/vent complex, while the others monitor more regional deflection of the earth resulting from larger-scale magma influx below surface.  By combining this data with seismic data (and in particular "harmonic resonance" which results from steady flow of magma up a conduit and subsequent chamber refilling), volcanologists can predict eruptions.
717408
Usually there are warning signs that something is happening. Active volcanos such as Mt St Helens are continusly monitored for changes such as increase in earthquake activity, change in the shape of the volcano. Scientists can actually see changes to the shapre of hte volcano by GPS surveys. Like what is happening in the Pacific at teh moment (cant remember the name of the volcano just now) they know something is going to happen, but they cant place a time on it, so they have evacuated hte people. Most people are evacuated before hte volcano blows, but those that have ignored pleas do so at they're own risk. And yes as the dude above me pointed out, by means of a road.
138240
WTF? It wasn't a yes or no question.\n\nYellowstone has a recurrance interval of 600,000 years.  That the average time between eruptions.  It's been 640,000 years since the last eruption.  However, don't get too excited, the standard deviation is HUGE.  On geologic time(10,000 yrs) there's a decent chance of eruption.  On human time (the next 60 years) there's about zero.
54493
Volcanoes are usually situated either at the boundaries between tectonic plates or over geology hotspots. Volcanoes may be either dormant (having no activity) or active (near constant expulsion and occasional eruptions), and change state unpredictably.\n\nSurprisingly, there is no consensus among volcanologists on how to define an "active" volcano. The lifespan of a volcano can vary from months to several million years, making such a distinction sometimes meaningless when compared to the lifespans of humans or even civilizations. For example, many of Earth's volcanoes have erupted dozens of times in the past few thousand years but are not currently showing signs of activity. Given the long lifespan of such volcanoes, they are very active. By our lifespans, however, they are not. Complicating the definition are volcanoes that become restless but do not actually erupt. Are these volcanoes active?
943300
I think the Viking probes had seismometers for detecting volcanic activity, but they found nothing I believe. Mars has been inactive, dry and probably lifeless for billions of years.
946468
Simple answer: distance and monitoring.\n\nPlacing sensitive probes on the volcano to monitor any movements, shifts, temperature change, growth, seismic activity, etc., will give some indications of what a volcano is up to. If vulcanologist's studying the volcano's activities consider an eruption is about to happen, then an early warning can be issued for an evacuation.\n\nVolcanic eruption cannot be stopped. Eruption prediction is an inexact science at best. Safety is in distance. Tourist beware.
424777
I'd think you could find two points with the same single variable like temperature, or something easier to visualize like height, but two variables is questionable. Suppose you had 2 altimeters that you could position remotely (and they automatically stayed at opposite points). Idealize height as being a smooth function of location. \nInitially the altimeters indicate unequal heights. When you move them one way the difference increases. Then move the opposite way to decrease the difference. Move a little bit, then reassess the relative changes, find a new direction if needed, and make another small step toward decreasing difference. Now mentally superpose the two surfaces you are surveying. If there are no height maxima or minima and the surfaces intersect, repeating this procedure should find a pair of zero-difference points. Now you can follow the contour of intersection of the surfaces and the difference remains zero. If the surfaces diverge in every direction there must be an altitude maximum or minimum in one or both survey areas; move until the extreme is off the survey area and there is overlap, and repeat the zero-finding procedure. There is an overwhelming probability that such a pair of areas, and therefore of points, can be found. Earth does not have a situation where one hemisphere's altitude range is completely separate from the other hemisphere's. The same goes for temperature and pressure. \nWhat about a second variable, say pressure? Suppose it too can be mapped to two intersecting surfaces. Project the zero-height-difference and zero-pressure-difference contours onto the same plane. If the two contours intersect anywhere, the two-variables-equal point pair has been found. If they don't, you can't find one here; move to a whole new area.\nBy this logic you're extremely likely to find a pair of one-variable equality points, and pretty likely to find a two-variable pair of points. I know this is not a good mathematical answer, which should be a proof or disproof, but then it may not be provable or disprovable.
277069
The hotspots are stationary.  As the overlying oceanic plate slowly moves over the hot spot, volcanic activity "pops" up through the plate, showing the relative direction of plate movement.  If the plate changes direction, you will see a bend in the line of volcanic features (called seamounts).  Look at the Hawiian islands and the Emperor Seamounts.
1066571
stratovolcano is a tall, conical mountain (volcano) composed of both hardened lava and volcanic ash. The shape of these volcanos is characteristically steep in profile because the lava flows that formed these volcanos were highly viscous, and so cooled and hardened before spreading very far. Such lava are classed as acidic to be high in silica. At the other end of the spectrum are shield volcanoes (such as Mauna Loa in Hawaii), which are formed from less viscous, basic lavas (high in metals such as magnesium and iron), giving them a wide base and more gently sloping profile. Many stratovolcanos exceed a height of 2500 m. They are often created by subduction of tectonic plates.\n\nAlthough stratovolcanoes are sometimes called composite volcanoes, volcanologists prefer to use the term stratovolcano to distinguish among volcanoes because all volcanoes of any size have a composite (layered) structure — that is, are built up from sequential outpourings of eruptive materials.
726835
A reference to a meterological term: see link\n\nhttp://en.wikipedia.org/wiki/Adiabatic_lapse_rate
226999
Here ya go : \nhttp://volcano.und.nodak.edu/vwdocs/volc_images/img_fuji.html
676415
Go here:\n\nhttp://www.fema.gov/kids/volcano.htm
64375
cooling and solidification of magma
754776
It measures the density of cumulative clouds. Good Luck !  :)
240915
Here is the answer! I leave the use of a calculator to you.\n\nAt a distance of X from the volcano,the dude saw the top at an angle of 37 degrees. Then at a distance of X-1000, he saw the top at 40 degrees. So, the common factor these two measurments have is the height of the mountain, speaking in geometric terms, the opposite of the angles. So you know tan = opposite /adjacent right? Therefore tan 37=(height of volcano)/x and tan 40 = height of volcano/(1000-x). Then, you equate x tan 37= (1000-x) tan 40. Now use your calculator and find the value of X. After that, plug that value into x tan37 = height of volcano. And then tada , you got your height!
783368
Here, plateau  means to level-off.  Level-off means the supply will reach a higher number, but after 2015 the number will stay about the same around that higher number.
652094
It's the rapid flow of material from a volcano that is accelerated by hot gases.\n\nHere's a good link for reference from the US Geological Survey site.  It has some better definitions, pictures, and case studies of pyroclastic flows.\n\n\n"Pyroclastic flows are high-density mixtures of hot, dry rock fragments and hot gases that move away from the vent that erupted them at high speeds. They may result from the explosive eruption of molten or solid rock fragments, or both. " http://volcanoes.usgs.gov/Hazards/What/PF/pcflows.html