Natural Disasters Test 2

Front 1

island arc

Back 1

They are long linear chains of volcanoes lying along the leading edge of lithospheric plates

Front 2

Stratovolcanoes are composed of mixed layers of ______________ and ________________
material

Back 2

lava & pyroclasitc

Front 3

Stratovolcanoes are composed mostly of ______ composition lava and pyroclastic layers though flows and pyroclastic layers of ______ to _____ composition also occur.

Back 3

intermediate (andesitic)

mafic (basaltic) to rhyolitic (silicic)

Front 4

Shield volcanoes are built up primarily from highly fluid, low viscosity ___________________
lava.

Back 4

basaltic

Front 5

smallest volcano

Back 5

cinder cone

Front 6

what types of volcanoes are in island arcs

Back 6

stratovolcanoes (composite volcanoes)

Front 7

What is the average dip of subducting plates?

Back 7

45 degerees

Front 8

The trench is a deep bathymetric furrow marking the location where one plate descends or subducts beneath another.  If the dip of the subducting plate is less than 45, then what happens to the distance between the locus of volcanic arc activity in the island arc and the trench?

Back 8

It will lengthen

Front 9

If the dip of the subducting plate is greater than 45, then what happens to the distance between the locus of volcanic activity and the trench?

Back 9

It will shorten

Front 10

If water and other types of volatiles are introduced to the lower lithospheric mantle, then what happens?

Back 10

it melts

Front 11

Mohorovicic discontinuity

Back 11

The boundary between the mantle and the crust

Front 12

Geologist describe the accumulation of magma at the Moho as:

Back 12

Ponding and Underplating

Front 13

After leaving the Moho magma may eventually accumulate in a large chamber lying beneath a
volcano.  What is the chamber called?

Back 13

subvolcanic magma chamber

Front 14

hotspots are known to occur in

Back 14

intraplate settings

Front 15

Yellowstone and Hawaii

Back 15

Hotspots

Front 16

Where hot spots exist hot plumes of mantle rock rise without significant loss of heat to areas of lower confining pressure.  What would happen to the head of the plume if it rises to just a few kilometers beneath the sea bed or land surface?

Back 16

it would melt

Front 17

Rifts are ___________________

Back 17

elongate basins produced by the stretching or pulling apart of the crust

Front 18

the plates and microplates that make up the East African Rift
System:

Back 18

african plate, arabian microplate, somalian microplate

Front 19

The East Africa Rift System is a

Back 19

young rift

Front 20

ponding or underplating

Back 20

the accumulation of magma at
the crust‐mantle boundary

Front 21

viscosity of magma

Back 21

is its internal resistance to flow when a shear stress is applied to
it.

Front 22

magma with a high viscosty

Back 22

..has a high internal resistance to flow, while with a low viscosity if more flui

Front 23

solubility

Back 23

of any substance, refers to its ability to be dissolved within a liquid

Front 24

vapor pressure

Back 24

is the pressure produced by H2O
and CO2 gas separating from the magma at a given temperature under equilibrium conditions.

Front 25

confining pressure

Back 25

the pressure exerted by the column of rock lying above the magma.   
Obviously, the greater the column of rock overlying the magma, the higher the confiningpressure.

Front 26

If the exsolution of H2O and CO2 is a result of lowered confining pressure, then it is
called

Back 26

first boiling or isothermal decompression

Front 27

If the vapor pressure increases within the magma, and if it rises to equal that of the confining pressure

Back 27

then second or retrograde boiling occurs.

Front 28

eruption column

Back 28

is the region of hot gas and fragmented pyroclastic materials lying above the fragmentation surface

Front 29

occurs in the lower part of the eruption column where it
consists of pyroclastic material, some still plastic, and gases driven vertically upward through
expansion

Back 29

gas thrust region

Front 30

convection thrust region

Back 30

comprises about 90% of the eruption column and occurs where, due to the fall out of pyroclastic particles, the density of the eruption column becomes less than that of the atmosphere, and hence the column is driven upward by convective up rise.

Front 31

a rock derived from an air‐fall deposit composed
mostly of as

Back 31

air-fall tuff

Front 32

air-fall lapillistone

Back 32

rock composed of lapilli falling towards the earth

Front 33

Pyroclastic flows, (nuees ardentes: French for "glowing clouds")

Back 33

are mixtures of hot gas, tephra, and rock fragments 161-241 kilometers an hour

Front 34

Volcanic Explosivity Index

Back 34

index is based on the volume of material erupted, the height of the eruption column, and the duration of the eruption (range 0-8)

Front 35

volcanism in the East African Rift
System

Back 35

a. Magma effuses out of fissures to form flood basalts
b. Magma effuses out of a central vent to form large shield volcanoes
c. Magma explosively erupts to form large stratovolcanoe

Front 36

Eventually the East African Rift System will ...

Back 36

East African Rift System will subside beneath the Indian Ocean, and will be replaced by a mid‐ocean ridg

Front 37

As magma cools, viscosity

Back 37

increases
(Temperature decreases, viscosity increases)

Front 38

Rhyolitic magma is more viscous than both _ and _ magma

Back 38

basaltic and andesitic

Front 39

magma with more dissolved water will be

Back 39

less viscous

Front 40

is the pressure produced by the weight of the overlying column of rock.  It will increase with depth

Back 40

confining pressure

Front 41

Does the solubility of the volatile phase increase or decrease with depth in the crust?

Back 41

increases with depth

Front 42

"The Volatile Phase"

Back 42

This phrase means that the volatiles came out of solution as an independent separable
component.  In other words they did not remain dissolved in the solution

Front 43

the rate at which the volatile phase separates from the magma is _______ ___ the rate at which it is dissolves back into it.

Back 43

equal to

Front 44

Exsolution of the volatile phase will occur when the ________ _______________ equals the
____________ ____________.

Back 44

vapor phase = the confining pressure

Front 45

The general process of exsolution of volatiles from a magma is called

Back 45

vesculation

Front 46

The fragmentation surface forms when the volume of bubbles is about what percentage of the total volume of the magma column

Back 46

75%

Front 47

The point source from which all material blasted out of the volcano is derived separates the exsolving magma below from the eruptive column above

Back 47

the fragmentation surface

Front 48

Tephra that is pulled by gravity out of the eruption column commonly blankets the landscape.  
Such deposits are called

Back 48

ash-fall deposits

Front 49

logarithmic

Back 49

The scale of the VEI is

Front 50

The VEI for a Strombolian type eruption is

Back 50

1, 2

Front 51

The VEI for a Volcanian type eruption is

Back 51

2, 3, 4

Front 52

The VEI for a Plinian type eruption is

Back 52

4, 5, 6

Front 53

The VEI for an Ultraplinian type eruption is

Back 53

6, 7, 8

Front 54

Hawaiian type eruptions: High and low

Back 54

High Fluidity, Low Viscosity basaltic lava

Front 55

. In what types of eruptions would you expect to see lava fountaining?

Back 55

hawaiian and strombolian

Front 56

In what type of eruption would you expect to hear intermittent explosions sometimes called burps

Back 56

Strombolian

Front 57

Which of the following types of eruptions typically involve andesitic to dacitic magma and result in explosive eruptions with columns reaching 5 to 10 kilometers in height

Back 57

volcanian

Front 58

Which of the following types of eruptions are characterized by large explosive events that form dark eruption columns of tephra and gas that extend into the stratosphere and can last from hours to days?  
They commonly form from volatile‐rich dacitic to rhyolitic magma, and involve the wide spread dispersal of tephra, and pyroclastic flows or nuees ardentes

Back 58

Plinian

Front 59

Which of the following produces an eruption column that reaches 45 kilometers or more into
the atmosphere?

Back 59

ultraplinian

Front 60

are openings such as small vents or cracks in or around a volcano that emit steam and gases such as carbon dioxide (CO2), sulfur dioxide (SO2), and hydrogen sulfide (H2S),

Back 60

Fumaroles

Front 61

how hot are fumarole

Back 61

temperatures varying between ~100-1000 degrees

Front 62

CO2

Back 62

For
is an odorless, tasteless, and colorless gas that is extremely dangerous.

example, breathing air with more than 11% CO2 will produce unconsciousness in a minute or less

Front 63

SO2

Back 63

has a pungent smell and can cause inflammation and
burning of the eyes and respiratory tract, and difficulty in breathing.

Front 64

sulfuric acid form by

Back 64

When SO2 mixes with
water vapor it forms

Front 65

severe damage or destruction of vegetation, and severe irritation of the eyes, nose, and
throat.

Back 65

acid rain

Front 66

H2S (Hydrogen Sulfide)

Back 66

is a toxic gas that smells like rotten eggs.
Breathing H2S can cause a variety of ailments including headaches, fatigue, dizziness, excitement, diarrhea, and eye irritation.  
Inhaling large amounts of H2S gas can cause paralysis of the respiratory system and death.

Front 67

Small vents or cracks in an around a volcano that emit steam and gas

Back 67

fumaroles

Front 68

Acid Rain is ....

Back 68

Sulfuric acid

Front 69

Carbon dioxide (CO2) is an odorless and colorless gas that can suffocate people.  On October 21, 1986 a CO2 cloud was released from Lake Nyos.  It asphyxiated ~1700‐1800 sleeping villagers.  
Where is Lake Nyos?

Back 69

Cameroon

Front 70

limnic eruptions

Back 70

the name of the process that results in the emission of CO2 from lakes overlying
subvolcanic magma chambers?

Front 71

What are the essential conditions that must exist prior to a limnic eruption?

Back 71

There must be a lake that lies above a sub‐volcanic magma chamber.  CO2 emitted from the magma chamber enters the lake from below.  The cold bottom waters of the lake become saturated with CO2.

Front 72

In a deep tranquil lake saturated with CO2, will this gas phase remain in solution or will it exsolve in the deeper waters of the lake?

Back 72

CO2 will remain in solution

Front 73

If a deep tranquil lake saturated with CO2 is disturbed such that bottom waters rise to the lake
surface, then what will happen to the CO2?

Back 73

As the cold deep water moves upward it becomes warmer, and as a result, the CO2 will exsolve.
A cloud of poisonous CO2 gas may escape the lake and travel down the slopes of the volcano

Front 74

Should airplanes attempt to fly through ash clouds?  If not, then why?

Back 74

No, the temperatures inside jet engines are hot enough to melt volcanic ash.  The melt is then
swept into the cooler interior portions of the engine where it causes it to completely shut down,
i.e., flame out.

Front 75

Lightning is an electrostatic discharge between variously charged areas of the eruption
column or between charged areas of the column and the ground.  What process
produces the positive and negative electrostatic charges within the eruption column?

Back 75

Within the eruption column tephra tumbles and bumps into each other building up an electrostatic charge

Front 76

is an electrostatic discharge between variously
charged areas of the column or between charged areas of the column and the ground

Back 76

lightning

Front 77

lahar

Back 77

describes a hot or cold mixture of water and volcanic rock fragments flowing down the slopes of a volcano or river valley

Front 78

What type of volcano is most often associated
with the development of a lahar?

Back 78

Stratovolcanoes

Front 79

Mount Rainier lies near the beautiful cities of Tacoma and Seattle, Washington.  It posses two characteristics that are commonly associated with the generation of a lahar.  What are those two characteristics

Back 79

Stratovolcano with glaziers and snowfields at its summit

Front 80

If large lahars continue to occur at rates similar to those of the past, then what is the change of
a lahar reaching the Puget Sound lowland during an average human lifespan?

Back 80

10%

Front 81

According to the United States Geological Survey what are the two common processes that
initiate lahars on stratovolcanoes

Back 81

In melt‐water generated lahars, pyroclastic flows travel over and erode glacier ice and snow
thereby generating a mixture of water, ice, pumice, and rock fragments.  In landslide‐generated
lahars, landslides are initiated by magma rising into the volcano and destabilizing it by producing
steep gravitationally unstable slopes and/or by concomitant earthquakes.  In addition, landslide‐
generated lahars are also produced in steep to over steepened volcanic terrains underlain by
weak hydrothermally altered volcanic rock

Front 82

Mount Rainier is described as being composed of large volumes of hydrothermally altered
volcanic materials.  In terms of the generation of lahars, why is the presence of such material a significant concern

Back 82

Hydrothermally altered volcanic rocks are very weak and thus are highly susceptible to landslide development in steep to over steepened volcanic terrains.

Front 83

How are most lahars on Mount Rainier initiated?

Back 83

Most lahars on Mount Rainier are initiated by cold debris avalanches and are thus landslide‐generated lahars

Front 84

 What is the name of the
lahar that originated on Mount Rainer 500 years ago

Back 84

The Electron mudflow or lahar

Front 85

 What is the name of the
lahar that originated on Mount Rainer 5600 years ago

Back 85

The Osceola mudflow or laha

Front 86

Occurs along a steep gravitationally unstable slop

Back 86

characteristics of a cold debris avalanche.

Front 87

c. Occurs as a direct result of earthquakes produced by magma movement  
d. Occurs as a result of the high level injection of magm

Back 87

characteristics of a hot debris avalanche

Front 88

Were the initial events that created the Osceola and Electron lahars on Mount Rainier a cold or
hot debris avalanche

Back 88

cold debris

Front 89

A tsunami is a set of ocean waves caused by any large, abrupt disturbance of the

Back 89

sea surface

Front 90

The magnitude of an earthquake is a relative measure of its energy, while the focus is the location of the earthquake within the Earth’s interior.  Most tsunami are produced by 

Back 90

Small (<7) magnitude, deep focus (>30 km) earthquake

Front 91

What is the period of a tsunami

Back 91

The time it takes successive crests or troughs to pass a stationary point

Front 92

In the deep oceans, the wave height of a tsunami is often no more than

Back 92

1meter in height

Front 93

Wavelengths for tsunami typically range from _____________ of meters to over _____________
kilometers

Back 93

hundreds, 50

Front 94

Greater than 966 kilometers/hour

Back 94

. In the deep oceans what are the maximum speeds documented for a tsunami?

Front 95

Periods for tsunami range from __________ minutes to _______________ hours.

Back 95

10minutes to 2 hours

Front 96

When a tsunami approaches shore sea level appears to recede.  What is this phenomenon
called?

Back 96

drawdown

Front 97

Tsunamis often come ashore as a wall of water resembling a tidal bore.  The maximum vertical
height above normal high tide reached by the tsunami as it travels over the land surface is
referred to as __________________.

Back 97

runup

Front 98

Where is the Alika 2 landslide located?

Back 98

Off the SW coast of Mauna Loa, Hawaii

Front 99

What caused the Alika 2 landslide?

Back 99

A large piece of Mauna Loa gave way and slide into the adjacent Pacific Ocea

Front 100

What was the runup for the Alika 2 landside

Back 100

400meters

Front 101

Are the residents living on Mauna Loa, Hawaii safe from a tsunami?

Back 101

Absolutely not.  The volcano continues to grow and thus portions remain highly susceptible to gravitational collapse.

Front 102

IIn 1883, a volcano lying within the Sunda Strait between Java and Sumatra violently erupted.  In
the surrounding coastal communities it produced a series of tsunamis that ultimately killed Krakatoa or Krakataabout 36,000 people.   What is the name of this volcano

Back 102

Krakatoa or Krakata

Front 103

on the French Caribbean island of Martinique in the Lesser Antilles in 1902

Back 103

Mount Pelée erupted

Front 104

Select from the list below all of the processes that preceded the main eruption of Mount Pelée?

Back 104

a. Fumarole activity and eruption of sulfuric gases
b. Minor volcanic eruptions and formation of small pyroclastic flows
c. Formation of a crater lake
d. Lahar developmen

Front 105

What was the maximum speed reached by the pyroclastic flow that engulfed St. Pierre and what is its estimated maximum temperature?

Back 105

e. 100 mph 1300
o
F

Front 106

How many people lived in St. Pierre prior to the May 8, 1902 pyroclastic flow

Back 106

29,000, 2 survivors live there now

Front 107

Were the citizens of Martinique safe following the May 8, 1902 main eruption of Mt. Pelée?

Back 107

No, volcanic activity continued for many days following the main eruption

Front 108

What happened to the community of Morne‐Rouge, Martinique, on May 30, 1902?

Back 108

A pyroclastic flow struck the community and killed 2,000.

Front 109

Large sustained volcanic eruptions eject into the atmosphere large quantities of ash and SO2 gas.  
Molecules of SO2 combine with water vapor to form droplets of sulfuric acid.  These tiny droplets along with volcanic dust form an aerosol.  How does the resulting aerosol affect the temperature of the Earth’s surface?

Back 109

They reflect the Sun’s rays and thus cause a cooling of the Earth’s surface

Front 110

The eruption of Mount Krakatoa in the Sunda Strait between Indonesia and Java in 1883 is
classified as a VEI _____ eruption.

Back 110

6

Front 111

How high did the 1883 eruption column of Krakatoa reach

Back 111

25-36km

Front 112

The 1883 eruption was so violent that it literally tore the volcano apart.  It was so loud that it
was heard as far away as Rodriguez Island in the Indian Ocean.  This is a distance of about  

Back 112

4500km

Front 113

The cloud of sulfuric acid droplets and volcanic dust from the Krakatoa formed a stratospheric aerosol that was distributed by the wind around the globe.  During the year following the eruption it is estimated that global temperatures dropped by

Back 113

0.5degrees celcius

Front 114

Following the eruption of Krakatoa global weather patterns remained chaotic years and the global climate did not return to normal until

Back 114

1888