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Examples of Volcanic Disasters:
• Mount Vesuvius : A.D. 79  16,000 dead.
• Tambora, Indonesia 1815 92,000 died (mainly famine)
• Krakatoa – 1883 36,417 killed - mainly by tsunami
• St Pierre, Martinique - 1902 - 30,000 dead (pyroclastic flows)
• Nevado del Ruiz, Columbia, 1985 - >22,000 dead due to
mud/debris flows when eruption melted glaciers & snow.
• Lake Nyos, Cameroon: 1986 - 1,700 killed by carbon dioxide
VOLCANIC HAZARDS
Heimey 1973 -
Montserrat 1995 to 2010 & ?end – pyroclastic flow.
• Mount Pinatubo, Philippines 1991 ≈500 dead. Now lahars…
• Monserrat - 1996-98 & continuing activity. <30 dead.
• Alternately : Kilauea, Hawaii, one of the worlds most active
volcanoes and lava destroys houses, roads etc. Yet many
people live happily alongside. Also Etna frequently erupts but
only 77 known to have been killed in a very long history.
Plymouth, capital of Montserrat – now abandoned because of
pyroclastic flow risk.
Settlements
destroyed by
pyroclastic flows
and lahars
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Renewed activity with pyroclastic flows in February
2010 badly damaged the old airport to the NE of the
active Soufriere Hills area, and also affected the area
of the old capital, Plymouth. This was not a hazard for
people as the exclusion zone was being maintained.
However, since then things have been quiet, and quite
a few of the people who left Monserrat are now
returning. The new airport in the North of the island
has been receiving regular scheduled aircraft for some
time.
The tourist industry is also beginning to make a come
back – see www.visitmonserrat.com
http://www.volcanodiscovery.com/news.html
Volcanic Activity News in Past Week May 2016
Fuego Volcano, Guatemala Thu 19 May. Relatively large
pyroclastic flow.
Santiaguito, Guatemala Mon 16 May. Ash to 3-4km.
Etna, Sicily 18 & 19 May. 1st paroxysm with lava fountains
from 3 or the 4 summit craters. A second paroxysm on the 19 th
with lava flow from one crater – ending later in the day.
Sinabung, Sumatra, Indonesia. Thu May 16. Two moderate
sized pyroclastic flows.
Turrialba volcano, Costa Rica Thu May 16 New phase of
ash emissions & many earthquakes.
Pavlov Volcano, Alaska Peninsula Mon May 13
Earthquakes indicate renewed activity – no direct observations.
Stromboli Italy Mon 13 May Activity picked up, “Strombolian”
explosions.
Bardabunga, Iceland. Earthquake activity indicates renewed
eruption in months/years.
Volcanic Activity Today16 Dec 2016
Colima, Southern Mexico. There are no significant changes,
but it seems that the volcano has been a bit calmer during the
past 24 hours. Small to moderate vulcanian explosions
continue to occur, but their average frequency and strength
seems to have diminished a bit.
Fuego Volcano, Guetamala.
Shiveluch, Kamchatka Peninsula, Russia.
Dukono, Halmahera, Indonesia.
Sabankaya volcano, Peru.
Copahue, Argentina/Chile border.
The island of Tristan da Cunha is 10 km in diameter, a single
volcanic cone rising to 2,060 m (5,500m above the South
Atlantic ocean floor). Erupted in 1961, everyone evacuated to
England but returned in 1963, the settlement largely unaffected.
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SiO2
~50%
MAGMA TEMPERATURE
VISCOSITY
TYPE
(centigrade)
mafic
~1100
~60% intermediate
~1000
~70%
~800
felsic
low
GAS
CONTENT
ERUPTION
STYLE
low
nonexplosive
intermediate intermediate intermediate
high
high
explosive
N.B. In older books you will commonly find different terms:
basic is now mafic, acid is now felsic.
Continental crust has a much higher percentage of felsic
magma, some intermediate and some mafic magma.
Distribution of World Volcanoes
Oceanic crust has mainly mafic magma - though sometimes
felsic magma e.g. Iceland is dominantly mafic magma with
basaltic lava most commonly – but Oraefi Volcano is felsic and
has produced devastating eruptions.
Magma produces much gas as pressures fall - Mafic (basic)
lavas are very fluid – gas easily escapes. Felsic (acid) lavas are
very viscous, so gas cannot easily escape, so felsic volcanoes
are much more explosive and thus much more dangerous.
Bardabunga, Iceland, 31 August 2014. Gas escaping through
molten lava produces “fire fountains”. (Mafic Magma)
YouTube : copy the titles and view for yourselves.
Good video: Published on 16 Dec 2014 (Hawaii)
Title: Lava flows in Pahoa - Eruption Update
Most incredible volcano expedition ever 2012 - the full
version
Title: Marum Volcano's famed lava lake on Ambrym Island,
Vanuatu.
Title: Terrifying Pyroclastic Flows Sinabung Volcano
Eruption in 4K Ultra HD
Hekla, Iceland - fissure eruption, 1980 (Mafic magma)
In Iceland people rush off in their cars to see a new eruption!
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Photo by Sigadur Thorarinson with ordinary camera!
Hekla 1970
Mount St Helens before 1980 eruptions.
Mount St Helens:
30 March 1980
Ash lifted to 18,000ft
– significant hazard to
aircraft.
Mount St Helens: start of the great eruption of 18 May 1980.
The north side had been swelling for some weeks and suddenly
slipped downslope, releasing an enormous explosion of gas & ash.
Mount St Helens: Great
Eruption of 18 May seen a
long way off.
Ash disabled flying aircraft
and half the available
helicopters on the ground.
Mount St Helens: 1st view of north slope after big explosion.
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Mount St Helens: Trees destroyed by pyroclastic flow.
Mount St Helens: no footprints from pickup – no survivors.
Mud on tree shows
how deep the mud
flow was here.
Mount St Helens:mud and logs in melt floods for many miles.
Huge area of devastation
after the eruption. Far
bigger than predictions
because blast was
vented sideways.
57 killed, despite much
warning.
It is safer to have bigger
safety zones!
Lava dome growing in the crater of Mt St Helens, 1984
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Hazardous effects of volcanoes:
Lava – damage, sometimes severe, but little loss of life
(unless snow & ice melt).
Volcanic Gases – sulphides, fluorides & carbon dioxide ++
hazardous to humans and livestock (& poison grazing).
Ash – damage & deaths – loads on roofs – damage to crops
& grazing – damage to vehicle & aircraft engines etc. Volcanic
“bombs”.
Hot Ash Clouds = pyroclastic flows – very dangerous
Lahars/mud & debris flows/floods may be very bad – can
occur long after eruption over
Debris Avalanches – mega mass movements
Climate effects can kill – famine.
Other effects - tsunami
Armero had been previously destroyed by lahars in 1595.
The hazards from eruptions from Nevado del Rio were well
known to scientists and warnings had been given. There were
major risks from pyroclastic flows and lahars. The volcano had
been dormant for 69 years, but the new eruptive phase was
obvious with earthquakes and volcanic ash, including over the
town of Armero, 50 km from the volcano.
A risk map was available and in newspapers, but not widely
seen, & not easy to understand. People were advised to stay
indoors away from the ash, and a thunderstorm disguised a
renewed eruption phase, so that the lahar hit unexpectedly
burying and killing ¾ of the 28,700 people in the town.
Armero, Columbia, was completely destroyed by a lahar in
1985, with 23,000 killed. A remote eruption melted snow & ice
and the lahar surprised the town when it struck.
The lahar moved at 12m/s (43kmph) and was 30m deep. It
was followed by a series of smaller lahars. Rescue efforts were
delayed by the mud.
In June 1991, the second largest volcanic eruption of the
twentieth century occurred in the Phillipines, only 90 km (55
miles) NW of Manila at Mount Pinatubo.
The eruption began in July 1990 with a massive earthquake.
In April 1991 explosions with limited ash triggered the start of
evacuations.
The eruption climaxed in the ejection of massive amounts of
volcanic ash and sulphur dioxide on 15 June 1991.
Despite over 200,000 people being evacuated, the ash, made
heavier by rain from a tropical storm, collapsed many roofs and
killed between 200 and 800 people.
However the climatic effect of the sulphur gases was
enormous. In 1992 & 1993 the Northern Hemisphere was
cooled by 0.5 to 0.6oC and the whole planet by 0.4 to 0.5oC.
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Volcanic ash and aircraft - Eyjafjallajokull 2010
Lourdes, Pinatubo, part buried
by a lahar.
Following the 1991 Mt Pinatubo eruption more people have died
due to lahars (mud flows) than died due to the initial eruption.
Thick volcanic ash and heavy rain (frequent typhoons) produces
many lahars. 100,000 have lost their homes.
From: Geoscientist Online 15 April 2010
If your flight has been cancelled today because of
high level volcanic ash from Iceland, read this.
“Good evening ladies and gentlemen. This is
your captain speaking. We have a small
problem. All four engines have stopped. We
are doing our damnedest to get them going
again. I trust you are not in too much distress.”
Captain Eric Moody, flight announcement, 24 June 1982.
Volcanic eruption with ash in the Indonesia area!
Huge volumes of glassy ash because the erupting magma was
chilled by erupting under a glacier.
Problems for aircraft from volcanic ash.
Volcanic glass can melt onto turbines and clog them.
The ash can sandblast and obscure windscreens.
The ash can clog sensors especially speed indicators
but also engine sensors.
Electrical effects can upset radio communication.
There will be a bigger Icelandic eruption some
time!
Laki 1783 eruption - 14 cubic kilometres of lava and almost a
cubic kilometre of ash. Estimated killed over six million people
globally – world’s deadliest historical volcanic eruption.
Poisonous gases (hydrogen fluoride & others) killed many
people and animals in Iceland. 25% of people and over 50% of
animals dead from gases and starvation.
120 million tons of sulphur dioxide into the stratosphere, lowering
global temperatures. This caused crop failures in Europe,
droughts in India, famine in Egypt and Japan's worst famine
ever. MILLIONS starved to death.
Huge quantities of sulphur dioxide also drifted across Europe at
low level. Parish records in Britain indicate that 23,000 outside
workers died from sulphur dioxide poisoning in Britain!
Laki –biggest ever historic lava eruption, 580km2, flowing up to 60km in 1783
If Volcanic vent in Oldham, lava might have flowed to Liverpool Pier Head!
Mississippi froze at New Orleans and ice on the Gulf of Mexico.
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Tenerife – Scar of massive debris avalanche (NE of Mt Teide)
Such a massive debris avalanche could produce a tsunami!
Vesuvius & Naples. Blue on land is mainly SETTLEMENT!
Pompei Street, with Vesuvius in background.
Crater of Vesuvius.
Body cast at
Pompei.
Body cast and artifacts in store, Pompei.
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Herculaneum.
Heimey, Iceland 1973. Ist night, Jan 27, 2am. A long fissure opens with “fire fountains”.
Herculaneum water gate – hot pyroclasic flow killed many here.
Heimey 1973 – 1st morning – 27 January. Fire fountains from fissure continue.
Pipes carrying
large volume of
water to cool
lava. NB Steam
rising.
Fear of harbour
being blocked, =
the end for a
fishing town.
Heimey 1973 – lava advancing on houses
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Heimey 1973 –
lava piled against
fish factory – later
repaired.
Heimey 1973 – volunteers shovelling ash from roofs to prevent roof collapse
Safe to have people on site because basaltic (mafic) lava is so much less explosive.
Heimey 1974 – These
houses had been
completely buried and
quite a bit of ash has
already been removed.
Heimey 1974 –
clearing ash from
houses. Some
houses had been
completely buried and
some roofs collapsed.
There were problems
with steam damaging
buried houses, so
trenches were dug to
allow steam to escape.
Heimey – before 1973 eruption.
Heimey late summer 1973
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Heimey Before and After the 1973 Eruption
Popocatapetl volcano, just east of Mexico City. It is the most active volcano in Mexico
with 15 major eruptions since the Spaniards arrived in 1519 ( last major 1947). Over
25 million people live in the vicinity of Popocatapetl, including 18 million in Mexico City.
Popocatapetl Crater 1976
Volcanic ash east of Mexico City – many millions are at risk from volcanic hazards
Renewed activity in early 1990’s and mountain closed to visitors.
This picture was 16 April 2016 - lava fountain with incandescent
material thrown out NE to 3.5km and ash several km high (in night).
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Boiling water in pond, Geysir, Iceland.
Predicting future eruptions:
Study eruption history from records and geology (how far
lavas extended, pyroclastic flows?, lahars etc)
Monitor Earthquakes
Monitor gas emissions – changes in composition often warn
Geysir Strokkur
at Geysir,
Iceland
Swelling of the ground – instruments or simple observations
Hotspots – dead vegetation etc – ground observations
Start of ash/lava eruption. Satellite images useful in remote
areas.
Volcanic activity not all bad.
Geothermal power – Los Azulfres, Mexico (also New Zealand, Iceland)
Bathing in hot pools. Los Azulfres, Mexico
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Thank you for your attention
Eggs for the picnic. Los Azulfres, Mexico
Swimming in the hot pools at Landmannalauger is popular with
Icelanders & visitors.
If anyone would like a pdf file with
all the slides from today please
write your email address on the
list and I will send a pdf attached
to an email.
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