An example of the level of detail needed for A2 case studies and a discussion of the Mount St Helens 1980 eruption.

1. RICHARD HUISH COLLEGE 01/06/2009
The Huish Volcanologist
Mt St Helens - What on Earth Happened?
Nearly 30 years ago, Americas most beautiful volcano came to life after a 120 year
period of dormancy in an explosive demonstration of earths terrifying power. This issue
discusses the event, what effects the eruption had, how far on the road to recovery we
are, and how much longer it will take. Most importantly this issue will question; can
America cope with this disaster again?
Referred to as the event that umns under 3km high)
spawned the birth of Modern
The United States Geo-
Inside this issue: volcanology as a science, May
logical Survey (USGS)
the 18th 1980 is a day burned in
had been on site since
May 18th 1980 1 the memory of millions of scien-
the start of the activity.
tists, residents and observers.
A series of seismometer
The Primary Impacts 2 This was the first time a volcano-
and geodetic stations
logical event was so well record-
MSH Lahars 2 (Geodesy is the study of
ed, monitored and predicted, and
the shape of the earth)
then broadcast around the world.
Long Term Recovery 3 were positioned around
Important to scientists and stu-
the volcano.
Potential Hazards 4
dents alike as the only recent
case study iof a major acidic By April the 3rd, the
eruption in an MEDC, the les- governor had declared a state of magma and other ejectiles that
Further Reading 4
sons learned from this cataclys- emergency and order the evacu- moved at speeds of between
mic eruption were far reaching, ation of most of the citizens 220km/hr at the start to over
and led to many advanced moni- within the immediate danger 650km/hr over 20 miles away
toring systems being installed on zone. One infamous resident, from the vent. The combina-
other deadly volcanoes around Mr. Harry Truman, was among tion of the slide and flow
the world. those who refused to leave his caused the lake level to be
property and disbelieved the raised by 90m, feeding the
In early march, the first signs of new ash deposits with water
geologists warnings.
significant activity since 1840 creating Lahars, and stripping
were detected. Starting as a small As the eruption continues in
bare the 600 square KM of
swarm of earthquakes around the small bursts and harmonic trem-
surrounding pine forests.
volcano. Within 48 hours from ors for the next month, the pub-
Timeline:
noon on March 25th, over 174 lic began to loose interest, and This was the first time geolo-
March—EQ’s signal evacuated residents exerted gists had ever realized the a
quakes of magnitude 2.6 and
awakening from a 123
over were recorded. By the week pressure on geologists to allow volcanic blast did not neces-
year sleep
of the 18th of May, there were 8 them back into the exclusion sarily go straight upwards, but
April—State of Emer- zone on the 17th of May, a se- can come laterally out of the
magnitude 4 or higher quakes per
gency and evacuation
day. cond trip back to houses for cone. For USGS Volcanolo-
of residents and tourists
possessions was planned for 10 gist David Johnston, pictured
May 18th—massive For the next two months, the
O'clock the next morning. left, this realization came too
landslide triggers the North side of the mountain
late as he was directly in the
first lateral blast ob- swelled as magma was injected At 8:32 that Sunday morning, a
path of the blast.
served in history killing into the chamber, pushing the Magnitude 5.1 tremor loosed
57 people the north face and triggered a The eruption continued until
north face upwards and out-
wards. This massive landslide. The removal October 1980, killing 57 peo-
started to desta- of just under 3 Km3 of mass ple and the effects were felt as
bilize the slope, above the magma chamber trig- far away as Wales. Even today
and numerous gered a massive eruption about the volcano is still rumbling,
small collapses 7 seconds after the slide. The but much has been learned that
and small erup- landslide was a significant vol- aids in current prediction and
tions were ob- ume of material, however, the management around the
served. initial release of pressure creat- world.
(eruption col- ed a pyroclastic blast of molten

2. Page 2 The Huish Volcanologist Special Edition
(400 m) and left a crater 1 to 2 miles (2 to 3 km) wide and
The Primary Impacts 2,100 feet (640 m) deep with its north end open in a huge
breach. The Ash and subsequent 17 pyroclastic flows deposit-
The impacts of any geomorphologi-
ed ash in 11 US states. 4 Billion Board feet worth of timber
cal event are split into primary and
was destroyed, one of the defining factors in the low mortali-
secondary. The most significant pri-
mary impact in this case was the ty rate was that as it was a Sunday, had it been any other day
blast, which at times crossed the of the week, 300 loggers would have been working in the
sonic boundary. The debris flow was blast zone.
superseded by a gas cloud moving Environmentally the devastation was total within the baslt
slightly faster, the average tempera- zone, for 30km around the main vent, the thermal blast
ture of these clouds is 1000 degrees. seared all life, and covered land and water alike with thick
Containing blocks the size of double ash deposits. 1500 elk and 5000 deer were killed, and as
Decker buses, molten lava
amany as 7000 big game animals such as brown
and parts of the volcano
bear. 12 Million Salmon and Chinook fingerlings
wall, this cloud instantly “The nature of
Caption describing pic- movement was (small fish) died as the lakes acidified and boiled,
vaporized water it came eerie.... The
ture or graphic. entire mass began and over 40 000 mature salmon were forced to flee
into contact with and to ripple and the waters through turbines they normally swam
carbonized all organic churn up, without
moving laterally. over.
matter. Then the entire
north side of the In terms of issues to populations, poor visibility
The blast itself did not last longer than 30 seconds, but summit began
within that time it had devastated areas as far away as sliding to the closed several airports in Washington state, Inter-
north” state 90 was closed for two weeks, 1000 commer-
30km, and the extreme heat caused devastation much
further afield. cial flights were cancelled. Sewerage and water sys-
Keith Stoffel,
Geologist flying tems were clogged, with many local businesses clos-
What the blast did, was to open up the throat of the over the eruption
column
ing for the duration.
magma chamber, relieving pressure and causing mag-
ma from deeper sources to ruch into and recharge the
chamber. Once started, the volcano formed an eruption column
that reached 19km high within 10 minutes. This column fed other
flows that sped down the flanks, and volcanic bombs to fall fur-
ther from the vent which created pits almost 20m deep and send-
ing as almost 2km up into the air.
Fifty-seven people were killed and 200 homes, 27 bridges,
15 miles (24 km) of railways and 185 miles (300 km) of high-
way were destroyed
The eruption ejected more than 1 cubic mile (4 km³) of materi-
al. A quarter of that volume was fresh lava in the form of ash,
pumice, and volcanic bombs while the rest was fragmented,
older rock.
The removal of the north side of the mountain (13% of the Melting of the summit glaci-
cone's volume) reduced St. Helens' height by about 1,313 feet ers—fed theinitial lahars which
started in the summit zone at
MSH: Lahars around 90MPH slowing to
3KMPH 30 km away. These
One of the most significant hazards flows moved upstream along
during and after the eruption was the the Cowlitz river by 27 miles, in
generation of lahars. These came a 4m high wall of muddy water
from several sources and were used
as an example of what could and in- The mountain streams and
deed did happen in the Nevado Del brooks—becoming clogged
Ruiz eruption. with ash
Spirit lake– overwhelmed by In total the lahars were responsible for
the landslide and the lateral some major damage including de-
blast, the water boiled killing stroying 27 bridges, 298km of high-
all aquatic life and then mobi- ways, 25km of railways and stranding
lized the settling ash into a 31 ships in the Columbia River whose
lahar depth was reduced from 12 to 4m.

3. The Huish Volcanologist Special Edition Page 3
Long Term Recovery and Impacts
The eruption phase that started in May ash and the surrounding intact forests (Unfortunately
“half hour
continued actively until October of that provided a source of plants that grew the advice was helicopter rides
year. There have been numerous phas- into the damaged area, and birds and not heeded, and costing $149 per
es pf activity since then, but don as animals transported seeds through drop- the Lahars gener- person give you a
dramatic as the 1980 eruption. The pings into the fertile ash. ated by Glacier
effects of that day have had reverbera- melt killed 23000
guided tour of the
Social:
tions around the world, and can be split people). summit”
into distinct groups: 57 people were killed in the eruption, by
The eruption also
the time the blast reached them it
led to a significant over hall of most mon-
was still 360 degrees Celsius causing
itoring stations in the Cascades range,
instant asphyxiation. Among those
and the CVO (Cascades Volcano Observa-
that died were a National Geograph-
tory) re-evaluated the status of several
ic Photographer and David John-
other volcanoes.
ston, a young USGS volcanologist
who was stationed immediately in Economically:
front of the bulge. The ridge were
The most up to date estimate of the costs
he died has been renamed Johnston
of the eruption was $2.74 Billion in 2007
Ridge. Over 200 homes were de-
dollars. Congress sent $951 Million to
stroyed completely by the blast, the
FEMA the US Army Corps of Engineers
loss of homes and land is a signifi-
and the Small Business Administration.
cant set back to local recovery.
Unemployment in the area rose by a fac-
Volcanological: There was a marked increase in depres-
tor of ten a few weeks after the eruption,
sion and other mental health issues in
The eruption ceased by 1982, but there and tourism in the region was crippled by
the months following the start of recov-
have been several renewed bursts the fact that the Mount Baker camp was
ery
since then. There have been 7 domes/ utterly destroyed and access to the area
spines since 1980, including the whale- On a more positive side, the information was restricted . Many conventions and
back, pictured above. These spines gained from observing this eruption with larger social gatherings were relocated
grow and collapse periodically, with the high tech equipment and a range of rele- away from the Washington area.
1987 third dome reaching 900m by vant experts on hand meant that signifi-
However, these effects were temporary,
800m. Following the pyroclastic flows cant advances in prediction capability
and once the national park was reopened
and lahars, ash removal from the state and monitoring were made. The under-
there was a resurgence of visitors who
took 10 weeks and cost $2.2 million. standing of the lateral blast phenomena
had observed the eruption on the news,
The flows were still at 300 to 420 De- and the lahars produced by the meting of
attracting an entire new group of volcano
grees two weeks after the eruption, summit glaciers and snow was used to try
based tourists. This influx still continues
and the interaction of groundwater and and aid the population of Armero during
today, in 1987 when the site was reo-
hot deposits caused numerous small the 1985 eruption of Nevado Del Ruiz
pened to climber, a permit was required
explosions within the flows, continuing for access to the faces costing $22/day,
for several months. and half hour helicopter rides costing
Environmental: $149 per person give you a guided tour of
the summit.
Although devastation within the blast
zone was total, all forms of life blown Mount St. Helens National Volcano Mon-
up, carbonized or buried in ash, recov- ument, which is run by the U.S. Forest
Service and straddles Cowlitz and Skama-
ery speed has taken scientists by sur-
nia counties, account for much of Cowlitz
prise. This picture at the bottom of the
County's $90 million annual tourism reve-
page shows the same site in 1988 and nue and pump about $15 million a year
2001, secondary succession has taken into Skamania County. About 2,400 jobs
place so rapidly partly due to the na- in both counties are tourism-dependent.
ture of the eruption. Unlike basic volca-
Educational:
noes like Hawaii, the erupted material
was ash and pyroclastics, meaning it Learning continues apace around the
volcano. There were 21 active periods
was already broken down into small
between 1980 and 1990, and a google
fragments, meaning weathering could
Scholar search reveals over 20,000 papers
take place rapidly. The buried seeds written about the eruption.
and bulbs could break through loose

4. RICHARD HUISH
COLLEGE Potential for Future Hazards
Geography Department One of the areas worst affected, that still poses a dangerous risk to the area, is Spirit
South Road Lake. Annihilated by the 1980 eruption, the blast hit the lake, sending water 240m up
Taunton
TA1 3DZ
the hillside, and blocking the outlet. This led to a 60 m rise in the level of the lake, which
within a month had become devoid of all oxygen and life. Scientists initially despaired
Phone: 01823 320800 that life would take years to come back, but by 1983, there was more biological activity
E-mail: milliew@richuish.ac.uk
than ever before, and fish had returned by 1993.
The risk the lake poses is of overflowing and remobilizing loose ash deposits as cold la-
hars. The outlet was blocked by loose ash and pyroclastic deposits, which being uncon-
solidated, will not hold indefinitely,. To reduce the risk of overflow and lahars, there is
no a drainage tunnel removing water and maintaining a safer lower level.
The other risks relate to periods of renewed activity, there will be lahars following signif-
icant rainfall, and small eruptions related to dome building and collapse. The risk is al-
ways higher over winter and is carefully monitored and managed by hazard mapping and
evacuation routes.
MSH is now one of the most heavily monitored volcanoes in the world. The information
it provides is invaluable for predicting other future eruptions
Useful Links
There is a wealth of information about the vol-
canoes on the web. The best source for infor-
mation is the USGS< who have the dedicated
Cascades Volcano Observatory (CVO):
http://vulcan.wr.usgs.gov/
An interesting comparison can be made by look-
ing at eruptive styles and management on Ha-
waii and in the Cascades, this link takes you to
the Hawaiian Volcanoes Observatory where you
can make detailed comparisons between the
risks posed by acidic composite cones and the
basic effusive activity in the pacific:
http://hvo.wr.usgs.gov/
There is an excellent documentary frequently
on TV called “The eruption of Mt St Helens”
made a camera team dropped in the blast zone
two days after the eruption, who found that
compasses did not work, and the volcano was
still erupting
The other good documentary with excellent
footage is “Seconds from disaster: the eruption
of Mt St Helens”.
Key Questions:
Evaluate the management of this hazard
The eruption of MSH in 1980 had only negative
impacts—to what extent do you agree with this
statement?