Natural Disasters Units 3 & 4
Place the following famous volcano events into the appropriate bins based on their VEIs.
8 - Yellowstone and Toba 7 - Tambora 6 - Pinatubo and Vesuvius 5 - Mt. St. Helens
About ___ of volcanism is associated with the edges of tectonic plates.
90%
Many hill-slope masses are weak due to preexisting geologic conditions such as ___
All of these choices are correct
Mt. Rainier, Washington, is number one on the danger list of many U.S. volcanologists because of its ___.
All of these choices are correct
Active volcanoes today in Oregon and Washington, including Mt. St. Helens, result from ___.
The subduction of the Juan de Fuca Plate beneath North America
The Italian city of ___ is trying to save itself from slow subsidence and sea level rise.
Venice
The moon is thought to have formed ___.
from material that coalesced after an impact between Earth and a Mars-sized object
Several geologic phenomena are being studied as signs of an impending volcanic eruption. These include seismic waves, ___, and the release of gases.
ground deformation
Most of the people killed by the Mount St. Helens eruption of 1980 ___
had gone around barriers meant to keep people out of 'harms' way
Water table
level of saturation underground; higher means more mass movements
Lava flow
molten rock moving downslope
Earthquakes in Hawaii are mostly related to ___.
movement of volcanic magma beneath the ground
Lahars
muddy water-laden rush of material downslope
Faults on which the dominant forces are extensional are recognized by the separation of the pulled-apart rock layers in a zone of omission; these are ___
normal faults
When oceanic lithosphere collides with another plate, the ___ in the process of subduction.
older, colder plate turns downward beneath the younger, warmer plate
Most earthquakes are explainable using ___
plate-tectonics theory
Pyroclastic Flow
rapid rush of gases and materials downslope
With compressional forces, the hanging wall moves upward relative to the footwall; this type of fault is referred to as a ___ fault.
reverse
The New Madrid earthquakes are apparently related to an old buried ___.
rift zone
The strike-slip San Andreas Fault in California is a ___ fault more than 1,300 km long.
right-lateral
The seismic-gap method of earthquake forecasting works by identifying ___.
segments along a fault that not moved for the longest amount of time
A mantle hot spot has generated a long-lived plume beneath Yellowstone National Park, and the North American continent is moving ___ above it about 2 to 4 cm/yr.
southwestward
When most of the movement along a fault is horizontal, the fault is referred to as a ___ fault.
strike-slip
Earthquakes are most commonly caused by ___
sudden earth movements along faults
What erupts in a geyser?
superheated water and steam
The intensity of an earthquake is influenced by all but which of the following?
the current air pressure
What is the cause of volcanism at Italy's Vesuvius, Stromboli, Vulcano, and Etna?
the subduction of Mediterranean seafloor beneath Europe
Human-caused and natural events can be distinguished using seismic waves because ___.
they produce different S and P wave patterns
Using the S-P timing method, epicenters can be located using seismograms from a minimum of ___ recording stations.
three
Our solar system formed ___
through collisions of matter within a rotating cloud of gas, ice, dust, and other solid debris
The large left step in the San Andreas Fault in the Los Angeles area causes compressive ruptures along east-west-oriented ___ faults as in the 1971 San Fernando and 1994 Northridge events.
thrust
In ___ masses move down and out by sliding on planes of weakness, such as faults, bedding, or clay-rich layers.
translational slides
Divergent Boundary
two plates are spreading apart
Subduction Zone
two plates of different densities are converging
Continent-Continent Collision
two plates of the same density are converging
Transform Boundary
two plates slide past each other
Using Fig. 5.19, determine which U.S. states have a very high or very low risk of a major earthquake in the next 50 years.
very high risk -Washington -California -Missouri -Alaska -South Carolina very low risk -Texas -Minnesota -Michigan -North Dakota -Florida
absorption and absorption
water binds with clay to weaken its strength
cement dissolving
water can dissolve minerals that bind rocks together
weight of water
water fills in pores in rocks, making them heavier
pore-water pressure
water in rocks at depth gets added pressure from above, creating quicksand
Liquefaction occurs when seismic waves cause ___.
water to be injected into sediment causing the grains to lose cohesion and behave like a fluid
piping
water underground can physically erode loose materials, leaving caverns
In magma, ___ is the most abundant dissolved gas.
water vapor (H2O)
Today, North America has several small- to medium-sized plates subducting beneath its ___.
western margin
In the 1989 Loma Prieta quake, the Marina District building collapses were extensive, and numerous destructive fires broke out, due to all but which one of the following?
widespread looting and arson
A shield volcano has a great ___.
width compared to its height
The sum of all the underlying causes can push a slope to the brink of failure, and then an immediate cause may trigger the movement. The immediate causes for mass movements include ___
All of these choices are correct
Violent causes of death from volcanic eruptions include ___.
All of these choices are correct
Why does the magma from some volcanoes flow smoothly and relatively peacefully, while the magma from other volcanoes blasts forth violently and deals death over wide areas?
All of these choices are correct
If an island were to have developed approximately 52 million years ago from this same hot spot, where would it have most likely formed?
B
What was the origin of the gas that killed 1,700 people in Cameroon in 1996?
It leaked upward from basaltic magma underlying a lake
The ___ wave travels fastest and moves in a push-pull fashion of alternating pulses of compression (push) and extension (pull).
P
On 20 February 1943, a new volcano named ___, a scoria cone, was born when an eruption rose up through a farm field near a village in Mexico.
Paricutin
___ eruptions are the most violent types of explosive eruptions.
Plinian-type
The most famous of all volcanoes probably is Vesuvius, and the most famous of its eruptions are those of 79 CE, which buried the cities of ___.
Pompeii and Herculaneum
___ faults are commonly found at areas of plate convergence where subduction or continental collision occurs.
Reverse
___ are steep-sided, symmetrical volcanic peaks built of alternating layers of pyroclastic debris capped by high-viscosity andesitic to rhyolitic lava flows that solidify to form protective caps.
Stratovolcanoes
Sort the following mountain ranges into whether they are formed by continent-continent collisions or are formed at subduction zones.
Subduction Zones -Andes Mountains -Cascade Mountains Continent-Continent Collision -Caucasus Mountains -Himalaya Mountains
Which of the following wave types travels slowest through rock?
Surface waves
The volcanic explosivity index (VEI) measures size of volcanic eruptions on a scale of 0 to 8. Between 1500 and 1980, one VEI 7 eruption occurred. This was ___
Tambora in 1815
The most peaceful eruptions are ___ eruptions.
Icelandic type
What is the volcanic explosivity index (VEI) of a Yellowstone super-eruption?
VEI of 8
A highly viscous fluid is ___ . One common way to make a fluid less viscous is to ___ the fluid.
-very resistant to flow -add heat to
Rank the following speeds of mass movements from slowest to fastest:
1. Creep 2. Slump 3. Flow 4. Fall
After looking at the image, place the labels in the proper order from first to last to describe the eruption of Mt. St. Helens in 1980.
1. Preeruption 2. Bulge 3. Landslide/ Avalanche 4. Blast 5. Vertical eruption (Plinian) 6. Dome building
How many of the 17 earthquakes listed occurred at subduction zones?
15
The oldest rocks on the ocean floors are about ___ years in age.
200 million
California accounts for ___of all U.S. earthquakes of magnitude 3.5 and above.
23%
Earth is about ___ years old
4.5 billion
How many of the 17 earthquakes listed occurred in the 21st century?
6
Over ___ of Earth's magma extruded through volcanism takes place at the oceanic spreading centers.
70%
How many of the 17 earthquakes listed occurred at a Pacific Plate boundary?
8
Which state accounts for the greatest percentage of all U.S. earthquakes of magnitude 3.5 and above?
Alaska
Which of the following is not a divergent margin?
Aleutian Island Arc
The viscosity of magma is lowered by ___
All of the choices are correct.
Seafloor spreading generates ___ magma.
Basaltic
Which four states account for 91% of all U.S. earthquakes of magnitude 3.5 and above?
California, Alaska, Hawaii, and Nevada
Three basic classes of collisions include all but which of the following?
Continental plate versus mantle plate
The hot spot that formed the Hawaiian Islands through the present day is most likely to develop the next Hawaiian Island at which location marked on the map?
D
Before a landslide mass begins to move downhill, it must overcome ___
Inertia and friction
Which of the following steps taken by residents of Vestmannaeyjar, Iceland, were helpful in stopping and redirecting the lava flow during the 1973 eruption?
Helpful -seawater sprayed on lava flows to cool approaching lava. - Pyroclastic material bulldozed to create barriers and redirect flow. Not Helpful -Trenches dug to redirect lava out of town. - Movement of harbor to the other side of the island to avoid future disasters.
In 1883, __________ exploded and the resulting tsunami killed 36,000 people on Java and Sumatra.
Krakatau
The Mt. Pinatubo endangered people, animals, and property when its 1991 eruption resulted in ___
Lahars and pyroclastic flows
On 8 May 1902, a massive eruption of ___ killed 30,000 people in the town of St. Pierre.
Mont Pelee, Martinique
Crater Lake, Oregon, fills the caldera of ___ which collapsed about 7,600 years ago.
Mt. Mazama
A genuine success story of advance warning before a large eruption occurred in the Philippines in 1991 before the climactic eruption of ___.
Mt. Pinatubo
Volcanic eruptions with which of the following VEIs happen the most often?
VEI of 3
The Charleston, South Carolina, earthquake of 1886 occurred along a seismic belt that may be related to ___.
an adjacent oceanic fracture zone on the Atlantic seafloor
When the part of California west of the San Andreas Fault plows into Alaska it will ___.
become part of Alaska's southern margin
A rock smashed into many pieces by a scientist using a hammer is undergoing ___ deformation.
brittle
In August 1986, a gigantic volume of ___ belched forth from Lake Nyos in Cameroon and swept down the adjacent valleys asphyxiating 1,700 people.
carbon dioxide
The Toba eruption 74,000 years ago may have ___
caused a great reduction in the worldwide human population
Pyroclastic debris is ___
chucks of magma and rocks blown into the air by gas in a volcanic eruption
The natural materials most commonly associated with earth failures are ___.
clay minerals
The heat that transformed Earth early in its history came primarily from all but which of the following?
dark energy
If you are alone and get buried deeply in a snow avalanche, you will most likely ___
die of suffocation
A normal fault occurs when the hanging wall moves ___ relative to the footwall
down
In general, during an earthquake you should ___.
drop, cover, and hold on where you currently are
The best time for an earthquake to occur to minimize loss of life is ___.
during the night when most people are home and asleep
