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Originally posted by trusername
reply to post by cmaracing
I don't know if that is an unusually long list of "active volcanos"
but this is a great site - thanks for the link!
The USGS volcano observatories have the following goals in common:
* Research directed toward understanding volcanic processes and products.
* Evaluation of the ongoing hazards posed by the active volcanoes.
* Delivery of warnings to public officials regarding these hazards.
To realize these goals, it is necessary to conduct visual and instrumental monitoring of volcanic activity. Monitored changes common to each volcano include the following:
Seismicity -- Earthquakes commonly provide the earliest warning of volcanic unrest, and earthquake swarms immediately precede most volcanic eruptions.
Ground Movements -- Geodetic networks are set up to measure the changing shape of the volcano surface caused by the pressure of magma moving underground. Techniques commonly used include electronic distance measurement using a laser light source (EDM); measurement of tilt, both electronically and by repeated leveling of triangular arrays; and standard leveling surveys to obtain elevation changes. Additionally, very simple and inexpensive techniques, such as measuring crack openings using a steep tape, or noting changes in water level around a crater lake, have proven useful in certain situations. Upward and outward movement of the ground above a magma storage area commonly occurs before eruption. Localized ground displacement on steep volcanoes may indicate slope instability precursory to mass failure.
Geophysical Properties -- Changes in electrical conductivity, magnetic field strength, and the force of gravity also trace magma movement. These measurements may respond to magma movement even when no earthquakes or measurable ground deformation occurs.
Gas Geochemistry -- Changes in fumarole gas composition, or in the emission rate of SO2 and other gases, may be related to variation in magma supply rate, change in magma type, or modifications in the pathways of gas escape induced by magma movement.
Hydrologic Regime -- Changes in ground water temperature or level, rates of streamflow and transport of stream sediment, lake levels, and snow and ice accumulation are recorded to evaluate (1) the role of ground water in generating eruptions, (2) the potential hazards when hot, energetic volcanic products interact with snow, ice, and surface streams, and (3) the long-term hazard of infilling of river channels leading to increased flood potential.
Reconstructing a Volcano's History
Direct observations of volcanoes before, during, and after eruptions are essential to understanding a volcano's current behavior. The following studies complement information gained from monitoring and allow specification of the entire history of activity at a given volcano or volcanic field.
Geologic Mapping -- Geologic mapping places layered and more irregular deposits in the proper stratigraphic order and establishes their thickness and areal extent (and thus volume). Field descriptions of stratigraphic units are used to classify deposits and interpret the type of eruption that produced them. Mapping of ash deposits is used to correlate widely separated stratigraphic sections associated with a given volcano. Dating of ash layers is especially valuable to bracket ages of other, less extensive, deposits in individual stratigraphic sections.
Dating -- Dating of deposits establishes the time intervals in which eruptions or hydrologic events occurred. Techniques commonly used for young deposits are:
Carbon-14 -- This technique is used where eruptions overlie or incorporate vegetation or organic-rich soil and the carbon-bearing material is preserved.
Tree Rings -- Traumatic injuries to trees are represented by interruption or distortion of growth rings. In some cases, the season in which the event occurred can be specified based on knowledge of the yearly cycles of tree-ring growth.
Paleomagnetism -- In some areas, it has been possible to calibrate yearly changes in the position of the Earth's magnetic pole over the past several hundreds or thousands of years. In such cases the magnetic directions preserved in a series of eruptive deposits may be used to specify their approximate age.
Understanding Volcanic and Hydrologic Processes
Direct observation of volcanic and hydrologic events gives important but incomplete insights into the nature of volcano hazards. The following topics represent some of the avenues pursued to gain a fuller understanding of volcanic processes that control hazardous events.
Numerical Modeling -- Numerical modeling is used to test our understanding of physical processes, and hazard predictions can eventually be made on the basis of modeled events. Volcano-related processes amenable to modeling include (1) the gravity-driven flow of lava, hot pyroclastic debris, landslide debris, water-saturated mixtures of mud and rock, and water floods; (2) the dispersal of volcanic ash plumes and thickness of ash accumulation on the ground; (3) the development of eruption- or landslide-induced waves; (4) the time of occurrence and magnitude of outbreak floods from lakes dammed by volcanic debris; and (5) the flow of groundwater and the dynamics of hydrothermal systems.
Experimental Research -- Experimental research is necessary to model volcanic processes that can not be studied directly or safely in the field or are too complicated to model numerically. Experiments can be designed to simulate volcanic conditions and infer possible consequences of volcanic activity. For example, a gelatin mold injected with a colored fluid mimics patterns of subsurface magma movement. Specially designed flumes simulate the properties of dense slurries and help scientists to better understand the development and movement of debris flows. Other topics, such as the origin of magmas by melting in the Earth's mantle, and their subsequent crystallization, can be studied by a combination of laboratory experiments, numerical modeling, and interpretation of chemical variation in erupted lavas.
Excerpts taken from Wright and Pierson, 1992, Living with Volcanoes, The U.S. Geological Survey's Volcano Hazards Program: U.S. Geological Survey Circular 1073, and the Yellowstone Volcano Observatory Website, 2006, with some wording updated.
Originally posted by speaknoevil07
will a conventional gas mask work in these conditions? just curious.......
How long would the ash fall and could one travel afterward to safer area?
Originally posted by ressiv
EQ's are on a dept of approx. 300 to 500 mtr's
lake yellowstone is at places 600 mtr deep.... are de walls of the lake cracking??
[edit on 28-12-2008 by ressiv]
Originally posted by clay2 baraka
Originally posted by speaknoevil07
will a conventional gas mask work in these conditions? just curious.......
How long would the ash fall and could one travel afterward to safer area?
I think the big problem would be the oxygen displaced by the volcanic gases. A gas mask without an oxygen supply would be of little use.
Swarms of this nature are relatively common in this part of Yellowstone Park.
YELLOWSTONE VOLCANO OBSERVATORY INFORMATION RELEASE
Saturday, December 27, 2008 20:29 MST (Sunday, December 28, 2008 03:29 UTC)
YELLOWSTONE VOLCANO (CAVW#1205-01-)
44.43°N 110.67°W, Summit Elevation 9203 ft (2805 m)
Volcano Alert Level: NORMAL
Aviation Color Code: GREEN
PRESS RELEASE FROM YVO PARTNER UNIVERSITY OF UTAH SEISMOGRAPH STATIONS
Released: December 27, 2008 04:40 PM MST
The University of Utah Seismograph Stations reports that a swarm of small earthquakes of magnitude 3.5 and smaller is occurring beneath Yellowstone Lake in Yellowstone National Park, five to nine miles south-southeast of Fishing Bridge, Wyoming. The swarm began yesterday afternoon, Dec. 26, and has continued and intensified today. The two largest earthquakes in this swarm have been shocks of magnitude 3.5 and 3.4 which occurred at 1:17 and 1:26 pm MST, respectively, today. Many smaller earthquakes have also occurred, including three events this morning of magnitude 2.5 to 2.8 and a magnitude 3.2 event at 3:30 pm MST. Some of the earthquakes in the swarm have been reported felt by people in the Yellowstone Lake area. Swarms of this nature are relatively common in this part of Yellowstone Park.
Originally posted by Shirakawa
Originally posted by ressiv
EQ's are on a dept of approx. 300 to 500 mtr's
lake yellowstone is at places 600 mtr deep.... are de walls of the lake cracking??
[edit on 28-12-2008 by ressiv]
Wikipedia says that Lake Yellowstone is deep at most 118 meters, with an average depth of 42 meters, so yes, the last 'quakes are close to the bed of the lake but not THAT close.
en.wikipedia.org...
Fears of explosive volcano eruption closes Kamchatka Airport By Simon Hradecky, created Sunday, Dec 28th 2008 18:33Z, last updated Sunday, Dec 28th 2008 18:33Z Predictions, that the Koryak Volcano located about 13nm north-north-east of Petropavlosvk-Kamchatsky Airport (Russia) on the Kamchatka peninsula might burst into an explosive eruption, have closed the Petropavlosvk-Kamchatsky Airport. The Volcano has increased its eruptions in the recent days. Now collapses at the north-western slope of the 3456 meter high volcano at a height of about 3100 meters triggered fears, the volcano might burst into an explosive eruption. The volcano's last significant eruption was estimated about 3500 year ago, the last minor eruption was in 1957.
Earthquakes at Yellowstone
Thousands of small earthquakes rattle the Yellowstone region each year, and at least eight magnitude 6 or greater quakes have occurred in historical time. The largest was the magnitude 7.5 Hebgen Lake earthquake, which struck about 15 miles (24 km) northwest of the Yellowstone Caldera on August 18, 1959. That earthquake killed 28 people and caused damage of $11 million (equivalent to $70 million in 2003 dollars). The most recent large earthquake was a magnitude 6.1 shock inside the Yellowstone Caldera near Norris Geyser Basin on June 30, 1975.
An early written account of Yellowstone's earthquakes was given by Ferdinand Hayden in 1872, when his survey party was camped on the northeast shore of Yellowstone Lake:
We were informed by mountain-men that these earthquake shocks are not uncommon, and at some seasons of the year very severe, and this fact is given by the Indians as the reason why they never visit that portion of the country. I have no doubt that if this part of the country should ever be settled and careful observations made, it will be found that earthquake shocks are of very common occurrence.
So common were these shocks at Yellowstone Lake that Hayden named this camp "Earthquake Camp," an apt name because the area remains one of the most common sites of earthquake swarms in the Yellowstone region.
To document and monitor this seismic activity, the USGS installed a permanent network of instruments in 1973. University of Utah and USGS scientists have since pinpointed the locations of thousands of earthquakes in the Yellowstone region. Most are small (magnitude less than 3), shallow quakes that sometimes occur in swarms lasting days to weeks or longer. Swarms have been located both within the caldera and between the caldera and the rupture zone of the Hebgen Lake earthquake to the northwest. Although many earthquakes are associated with known active faults or former sites of volcanic eruptions (vents), some are not.