Natural Hazard Volcanic Eruption

205787-4Environmental Risk

Assessment for

Natural Resources Management

Active Volcano

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.

View from spa ce shattle

Aerial view of Pu`u `O`o eruption.

Volcanic Eruption on Ka mchatka Peninsula in Ru

ssia

Volcanic Hazards A assessing deposits formed by

(1) debris avalanches - 2( )sub pl i ni antopl i ni antephra

ee 3( ) pyroclastic flows and lahars,

and (4) lava flows. Ingeneral,areasimmediatelyabove of the Acti ve Crater are

in the highest hazard zone, pri marily from lahars or debris/py

roclastic flows associated with explosive eruptions.

Mount Pinatubo

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.

Vapour from fissile eruption

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c ash and dust deser t ed t he i r r el ocat i on si t e of War e na and cawed i n t ent s i n wh

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Rabaul vol canic ash

Volcanic gas released from Bocca Nuova, Etna driven

away from observer by str ong wind.

A huge cloud of gas, spewed fro m 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 gas Volcanic gas is released fro

m magma as it rises toward t he surface and during erupti

ons. Just as when the cap is r emoved from a pressurized

bottle of soda and dissolved gas forms bubbles, magmas

become bubbly as they rise t o the surface and depressuri

ze. The most common gas re leased by magma is steam (

H2

O), followed by CO2

(carb on dioxide), SO

2 (sulfur diox

ide), (HCl) hydrogen chlorid e and other compounds.

Becausevolcanicgasformsacidwheni t di ssol ves i n water, i t tends to attack rocks, breaking

them down into weak clay mate rials. The interiors of volcanoes often become seriously weaken

ed by this hydrothermal alterat ion, which makes them suscept ible to sudden landslides.

Volcanicgas i s one of the cl ues todetec t rising magma and a potential

eruption. Volcanic gas does not only leav

e the volcano through the centr al vent. But also escapes throu gh cracks or vents called fumar

oles.

Volcanic gas fatality at Adatara Volcano

Four hikers lost their lives due to volca - nic gas in a summit (Numano daira) crater o

n 15 September. A party of 14 enjoyed hikingnearthesummitinfoggy andcal mcondi ti on.They l ost a m

ountain trail and wandered into the cra ter, looking for the trail. Three people f

ell in the crater floor, and a person who tried to help them did too.

According to the VOTIT, fumarolic gas f rom the southwestern part within the c

rater,contai ned - 0.5 % of SO2, 60 65 % H2S a - nd 33 37 % CO2 as dry basis, and gas co

l l ectedf roma mudpondonthe crater fl o or contai ned 241 256HSof %andCOof %. I nhal ati onof

e2

S as the most possible reason of this fatality. Volcanic gas can accumulated in th

elowlevel.Onthatday,thi s vol canohas rai sedi ts acti v ity,mud was spouting from two ponds o

n the crater floor and fumarolic activity has heightened in the southwestern pa

rt. They gave the public warning of dan

ger to approach the crater area.

NumaCrater

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 rates

Soil 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 air

Leachate analysis Determination of the amounts of gas adsorbed on surfaces of ash