Download
1 / 29
290 likes | 518 Vues
205787-4 Environmental Risk Assessment for Natural Resources Management. Natural Hazard Volcanic Eruption. Active Volcano. On September 30, 1996 a volcanic eruption started underneath Vatnajökull. This thunderous fight of fire and ice makes for one of nature's most dramatic spectacles.
E N D
205787-4Environmental Risk Assessment for Natural Resources Management Natural Hazard Volcanic Eruption
On September 30, 1996 a volcanic eruption started underneath Vatnajökull. This thunderous fight of fire and ice makes for one of nature's most dramatic spectacles.
Volcanic Hazards A assessing deposits formed by (1) debris avalanches (2) sub-plinian to plinian tephras, (3) pyroclastic flows and lahars, and (4) lava flows. In general, areas immediately above of the Active Crater are in the highest hazard zone, primarily from lahars or debris/pyroclastic flows associated with explosive eruptions.
Mount Pinatubo Ash column generated by the eruption of Mount Pinatubo, in the Philippines Luzon volcanic arc, on June 12-15, 1991, and was one of the largest eruptions of this century. The climactic event lasted about 9 hours and erupted over a cubic mile of rock material. It injected a 20- million ton, the largest sulfur dioxide cloud into the stratosphere to an altitude of more than 20 miles. Since 1978. It caused the largest aerosol disturbance of the stratosphere this century, although smaller than the eruptions of Tambora in 1815 and Krakatau in 1883. Sulfate aerosol formed in the stratosphere from sulfur dioxide in the Pinatubo cloud increased the reflection of radiation from the Sun back into space. Consequently, the Earth's surface cooled in the three years following the eruption, by as much as 1.3 degrees ( Fahrenheit scale) at the height of the effect. The sulfate aerosols also accelerated chemical reactions that, together with increased stratospheric chlorine levels from man-made chlorofluorocarbon (CFC) pollution, destroyed ozone and led to the lowest ozone levels ever recorded to date in the stratosphere.
1994 Rabaul eruption In April the people of Tavana, Valaur and Latlat, whose villages, estates of coconut and cocoa, permanent houses and buildings, dwellings, garden sites, sacred grounds and cemeteries are buried under 20 metres of volcanic ash and dust deserted their relocation site of Warena and cawed in tents in what used to be their homes
Volcanic gas released from Bocca Nuova, Etna driven away from observer by strong wind.
A huge cloud of gas, spewed from volcanos on one of Jupiter's moons, extends into space to a distance that is almost equal to that of the earth from the sun
Volcanic gasVolcanic gas is released from magma as it rises toward the surface and during eruptions. Just as when the cap is removed from a pressurized bottle of soda and dissolved gas forms bubbles, magmas become bubbly as they rise to the surface and depressurize. The most common gas released by magma is steam (H2O), followed by CO2 (carbon dioxide), SO2 (sulfur dioxide), (HCl) hydrogen chloride and other compounds.
Because volcanic gas forms acid when it dissolves in water, it tends to attack rocks, breaking them down into weak clay materials. The interiors of volcanoes often become seriously weakened by this hydrothermal alteration, which makes them susceptible to sudden landslides.Volcanic gas is one of the clues to detect rising magma and a potential eruption.Volcanic gas does not only leave the volcano through the central vent. But also escapes through cracks or vents called fumaroles.
Volcanic gas fatality at Adatara VolcanoFour hikers lost their lives due to volcanic gas in a summit (Numano-daira) crater on 15 September. A party of 14 enjoyed hiking near the summit in foggy and calm condition. They lost a mountain trail and wandered into the crater, looking for the trail. Three people fell in the crater floor, and a person who tried to help them did too.According to the VOTIT, fumarolic gas from the southwestern part within the crater, contained 0.5 % of SO2, 60-65 % H2S and 33-37 % CO2 as dry basis, and gas collected from a mud pond on the crater floor contained H2S of 41% and CO2 of 56%. Inhalation of H2S as the most possible reason of this fatality. Volcanic gas can accumulated in the low level. On that day, this volcano has raised its activity,mud was spouting from two ponds on the crater floor and fumarolic activity has heightened in the southwestern part. They gave the public warning of danger to approach the crater area.
Jessie Crain monitoring the volcanic gas samplingapparatus on the crater rim of Mt. Erebus.
Method Applications Direct sampling Collection of emissions in glass containers and on filters for laboratory chemical and isotopic analysis Spectroscopic and remote Ground-, airborne-, and satellite-based sensing techniques measurements of gases in volcanic plumes to obtain emission ratesSoil gas measurements Determination of diffusive fluxes of volcanic gases in volcanic regions Chemical sensors Continuous in-situ monitoring of the concentrations of volcanic gases in fumaroles, soils, and ambient airLeachate analysis Determination of the amounts of gas adsorbed on surfaces of ash
