GEOLOGY
VOLCANIC HAZARDS & MONITORING
NAME___________
Standards/Purpose
 Describe the composition of igneous rocks and their formation
 Describe how scientific knowledge helps decision makers with local challenges related to
volcanoes
 Understand how monitoring can give us information about volcanoes and types of
hazards they may produce
I. Volcanic ____________________ in History
Hundreds of thousands of people have been killed by volcanoes in the past several hundred
years.
A. Mt. _____________________, Italy:
1. 79 A.D. eruption produced ash and ______________________ that buried the
towns of _________________ (10 ft.) and Herculaneum (75 ft.).
B. Mt. ______________, Martinique:
1. 1902 eruption, pyroclastic flows killed _____________ people in the city of St.
Pierre.
C. Nevada del Ruiz, ___________________:
1. 1985 eruption produced ____________ that killed 23,000 people in the town
of _________.
D. Mt. St. ________________, Washington State:
1. 1980 eruption produced pyroclastic flows and lahars that killed ______
people.
E. ______________________, Democratic Republic of Congo:
1. Very fluid lava lake in crater drained in less than 1 hour in 1977. Lava moved
at 40 mi/hr, overtaking and killing about 70 people
F. ____________, Heimaey, Iceland:
1. lava from 1973 eruption threatened to block harbor. People fought back,
spraying advancing flow with seawater to cool & stop it.
II. Volcanic _________________
A. ____________________ Flows
1. ______________________ clouds of hot ________, gas and ___________.
2. One of the most dangerous of all volcanic hazards.
3. They are ______________ and flow down the __________ of volcanoes killing
everything in their path.
4. The temperature of the pyroclastic flow deposits at Mt. St. Helens was ____° F
two weeks after the eruption.
B. __________
1. Fine ___________________ (<2mm) that are erupted from a volcano.
2. Effects of ash:
a. causes _____________ of buildings to _________________
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b. damages _______________ of ________________ that fly into ash cloud
c. covers _______________ areas and makes them unusable for many years
d. may stay in upper _________________ and cause unseasonably _______
temperatures (Ex: year without a summer (1816), snow fell in New
England in June: caused by 1815 eruption of Tambora)
C. ________________
1. ________________ that form when volcanic ______ mixes with __________
(rainwater or glacial melt).
2. They can flow for long distances down from the slopes of volcanoes.
3. Can ____________ towns and people in their path.
D. ______________
1. ___________ (molten rock) that is expelled onto the earth’s surface from
volcanism.
2. One of the least dangerous of volcanic hazards.
3. Lavas are much ______________ moving than pyroclastic flows and lahars,
and in most cases people are able to get out of the way before lava reaches
them.
Example of exception: Nyiragongo, Zaire: ~300 people overtaken & killed by
lava flows.
III. ____________________ Volcanoes
A. Can we predict volcanic eruptions?
1. _____. We can’t say that a particular volcano will erupt at a certain time.
2. However, we are getting better at _______________________ volcanic
eruptions. Using different monitoring techniques, we can often say that an
eruption at a volcano is likely within a certain amount of time.
3. Each volcano is _____________. The background ___________________
(normal activity) of each volcano must be learned in order to detect changes in
activity that may signal an impending eruption.
B. _________________ Monitoring
1. Seismometers are used to detect volcanic _____________________.
2. An increase in the number of earthquakes, shallow earthquakes, or earthquakes
with a particular pattern can be an indication of increasing volcanic activity.
C. Ground _____________________ Monitoring
1. _________________ and lasers are used to detect changes in the ___________
of volcanoes.
2. These changes correspond to changes in the magma ______________.
3. Ex: the side of Mt. St. Helens bulged out as new magma entered the magma
chamber.
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D. ______ Monitoring
1. Several techniques are used to monitor gas emissions from volcanoes. Changes
in the ______________ of gases or the _________ of one gas to another may
indicate increasing activity. Types of gas monitoring include:
- COSPEC
- FTIR
- Direct sampling
2. __________________ Gas Monitoring
a. COSPEC stands for correlation spectrometer. It is an instrument that is
used to measure the amount of ________ (sulfur dioxide) in volcanic
__________________ (gas column that rises from the volcano).
b. Can be done at a distance from the volcano.
3. ______________ Gas Monitoring
a. FTIR stands for fourier transform infrared. It is an instrument that is
used to detect ________ in volcanic plumes.
b. Can be done at a distance from the volcano.
4. ________________ Sampling of Gases
a. Gases are sampled directly from fumaroles and bubbling springs and
analyzed in the lab.
b. A ___________________ is a small hole from which volcanic gases
escape.
c. A bubbling _______________ is a fumarole that is covered in
___________, and like its name implies is a hot spring through which
gases are bubbling.
d. Must be done up close and personal on the volcano.
IV. Ms. Brown’s volcano research
A. Dominica & St. Lucia, West Indies
1. Direct sampling of ______________ from __________________ and bubbling
_____________________ in hydrothermal areas.
a. _________________________ areas are places where _______________
is heated by _______________.
Ex: Yellowstone
2. Sampled gases were analyzed in the gas lab at ________ using gas
_______________________ and wet chemistry techniques.
3. Results were used to establish __________________ parameters of volcanic
activity on the two islands in order to ______________ the volcanoes for signs
of eruptions.

L.
Brown
Updated February 2013
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