GEL 017 - Final Review
The mid-oceanic ridges are the most volcanically active regions of the world - over _____ of the world's volcanism likely occurs along within rift valleys on mid-ocean ridge crests
80%
San Andreas Fault
A transform fault boundary separating the North American plate (moving southeast) from the Pacific plate (moving northwest)
How does vegetation affect landslide hazard? A) it removes water from the hillslope, increasing landslide hazard B) it adds mass to the hillslope, increasing landslide hazard C) it adds structure and strength to the hillslope, decreasing landslide hazard D) both A and C
C
Hanging wall block
Block above fault
Footwall block
Block below fault
Divergent margin
Boundary between plates that spread apart to open new ocean basins or the continual spread of older ocean basins
An earthquake's epicenter is A) the location along the fault at depth where slip initiates B) the location along the fault at the surface where the slip initiates C) the location on the surface directly above the point on the fault where the slip initiates D) the location along the fault where the greatest displacement has occurred
C
Effusive eruptions A) produce ash fall B) are generally explosive C) produce lava flows D) produce pyroclastic flows
C
Effusive eruptions A) produce ash fall B) are generally explosive C) produce lava flows D) produce pyroclastic flows
C
Explosive volcanic eruptions generally occur in which type of tectonic setting? A) transform boundary B) divergent boundary C) convergent boundary D) both B and C
C
"tectonics"
refers to large scale movement and deformation of Earth's outer surface (lithosphere)
The alignment of earthquake epicenters and volcanoes circumscribing the Pacific Ocean is called the __________ and is entire related to subduction zones
"Ring of Fire"
What are the interior structures of the Earth, described by composition?
- Crust - Mantel - Core
What are the three plate margins?
- Divergent - Convergent - Transform
What are the interior structures of the Earth described by strength?
- Lithosphere - Asthenosphere
As it enters the bay, the height of a tsunami wave ______ A) rises because more water from each wave is forced into less space B) rises because the wave energy increases C) drops because the wave must spread out and slow as it approaches the shore D) drops because as the waves breaks it rushes ahead as fast-moving swash
A
If you stood on one side of a left-lateral, strike-slip fault during a large earthquake A) the opposite side of the fault would be moving on your left B) the opposite side of the fault would be moving on your right C) your side of the fault would be moving up relative to the opposite side D) your side of the fault would be moving down relative to the opposite side
A
Magma with _______ will be thick; magma with _______ will be runny A) high silica; low silica B) low silica; high silica C) low viscosity; high viscosity D) Both A and C
A
Pore pressure and cohesion A) are competing effects that cause mass wasting hazard to increase and decrease respectively B) do not drastically influence landslide hazard in areas with human development C) combine to make water-rich magmas more viscous D) both A and B
A
The highest mass wasting hazard exists when the ______ and hillslope dip in _______ A) solifluction lobe; the same direction B) internal surfaces; opposite directions C) internal surfaces; the same direction, with the hillslope steeper than the internal surfaces D) head scarp; the same direction
A
The oceanic crust subducts under the continental crust because A) it is denser than continental crust B) it is denser than the underlying mantle C) it is less dense than the continental crust D) it is mainly basaltic in composition
A
The process associated with divergent plate boundaries include: A) creation and widening of ocean basins B) oceanic trench formation C) mountain-building D) all of the above
A
Tsunami hazard is greatest near what type of plate boundary? A) convergent subduction B) convergent collision C) divergent D) transform
A
Which of the following are characteristics of an effusive volcanic eruption? A) little water and low viscosity B) more water and higher viscosity of the magma C) low viscosity of magma and a narrow vent D) weak rocks around the vent and more water
A
Which of the following statements is TRUE? A) On Earth, the magnitude of earthquake increase as the frequency decreases B) On Earth, the magnitude of earthquake decrease as the frequency increases C) On Earth, the magnitude of earthquake increase as the frequency increases D) There is no correlation between the magnitude and frequency of earthquakes
A
While _______ can affect thousands of square kilometers, the greatest impact of this hazard is directly downwind if this erupting volcano A) ash fall B) pyroclastic flows C) lahars D) earthquake swarms
A
Fault
A fracture along which movement has occurred; offsetting features on opposite sides of the fault
Asthenosphere
A hot weak, semi-plastic layer of rock that underlies the lithosphere
85% of all earthquakes occur within _______ of the Earth's surface A) 10km B) 20km C) 50km D) 200km
B
Displacement (AKA offset)
Amount of slip on the fault occurring during an earthquake - displacement during earthquakes may range from a few centimeters for small quake to ten meters for a large quake
In the elastic rebound theory of earthquakes, which of the following is true? A) with continued motion of tectonic plates, continuous slip prevents stress from accumulating across a fault B) the fault remains "locked" by friction until the strain exceeds the frictional strength of the rock C) single earthquakes always must release all of the strain accumulated across the fault D) earthquakes are periodic, and occur at regular and repeating intervals on each fault
B
Large earthquakes and active volcanos are both common along A) divergent plate boundaries B) convergent boundaries C) transform boundaries D) transform and convergent boundaries
B
Select the set of mass wasting events that is in order from fastest to slowest A) fall; solifluction; flow; slide B) slide; flow; creep; solifluction C) creep; flow; slide; fall D) flow; slide; creep; slip
B
The 1994 Northridge earthquake A) produced major ground shaking but negligible uplift of the Transverse Ranges B) occurred on a blind thrust fault C) caused major freeway damage in Seattle D) had a large surface rupture which cut all through the San Francisco Valley
B
The Earth's lithosphere A) is generally 10000 km thick B) comprised of the crust and uppermost mantle C) very plastic in behavior D) all of the above
B
The Wadati-Benioff zone is A) the zone in a divergent margin where basaltic magma comes to the surface through seafloor spreading B) the belt of earthquakes that delineates the descending slab in the subduction zone C) the area around an earthquake epicenter that is most damaged by ground shaking D) the name of the subduction zone offshore of Washington and Oregon
B
What force must be overcome in order for a landslide occur in most cases? A) slope B) friction C) saturation D) gravity
B
Which of the following is NOT an earthquake-related hazard that occurred during the 1994 Northridge earthquake? A) wave amplification B) liquefaction C) landslides D) none of the above
B
Which of the following is a FALSE statement about intraplate earthquakes? A) the tectonic forces that trigger intraplate earthquakes are poor understood B) intraplate earthquakes occur infrequently and in tectonically stable regions C) intraplate earthquakes occur infrequently and near divergent margins D) intraplate earthquakes often cause damage over a much larger area than non-intraplate earthquakes
B
Which of the following is a true statement about volcanic gas monitoring? A) CO2 and SO2 are always reliable precursors of eruptions at all volcanoes B) gas monitoring is most valuable when it can be conducted over long enough time period to develop a unique baseline for each individual volcano C) gas monitoring can be conducted remotely and analyses can be done quickly D) only volcanoes that erupt effusively emit volcanic gases
B
Which of the following is true about predicting volcanic eruptions? A) we cannot predict volcanic eruptions B) we cannot predict exact timing of volcanic eruptions but with continuous monitoring can identify precursor events that often precede eruptions C) Precursor events such as earthquake swarms and ground deformation always preceded eruptions D) none of the above
B
Which of the following most accurately describes the process of creep? A) slow movement of deep-seated material down a hillslope B) slow movement of shallow material down a hillslope C) moderate movement of material down a hillslope, driven by high pore pressure D) rapid movement of material down a hillslope driven by exceeding the angle of repose
B
Which two main factors result in more violent eruptions? A) little water and low viscosity B) more water and higher viscosity of the magma C) higher viscosity of the magma and a narrow vent D) strong rocks around the vent and more water
B
Why are earthquakes along the east coast of North America felt over a greater distance than on the west coast of North America? A) Earthquakes are larger on the East Coast B) The older and "colder" East Coast crust transmits seismic energy more efficiently than crust on the West Coast C) Earthquakes tend to be smaller on the West Coast D) All of the above
B
With a pattern of earthquake ruptures migrating along the fault over the course of decades, which of the following fault systems may behave in a similar manner to the San Andreas Fault? A) the Alpine-Himalayan Belt B) the North Anatolian Fault C) the New Madrid Seismic Zone D) the Hayward Fault
B
_______ is molten rock at depth and ______ is molten rock at Earth's surface A) lava; magma B) magma; lava C) pyroclastic debris; lava D) lava; pyroclastic debris
B
In California, the mass wasting hazard is highest A) in the Sierra Nevada Mountains, where the mountains are highest and often have cliffs on one or more sides B) in the Bay Area, where there are many well-known active faults C) in the Los Angeles area, where there is combination of unstable slopes and extensive development of buildings and roads D) in coastal California, where precipitation is most common
C
In order to determine the epicenter of a large earthquake, we need to know A) the magnitude of the earthquake B) the MMI for the earthquake C) the difference in arrival time P and S waves from at least 3 distant locations D) all of the above
C
Large magnitude earthquakes can occur at depths up to a few hundred kilometers along A) mid-oceanic spreading centers B) transform faults C) the Wadati-Benioff zone D) all of the above
C
Large-magnitude thrust earthquakes, such as the one in Nepal on April 25th, can occur on both _____ and _____ plate boundaries A) continental collisional; divergent B) subduction; transform C) continental collisional: subduction D) divergent; transform
C
Magma that is forcefully ejected into the atmosphere as small particles is called A) lava B) lahar C) pyroclastic debris D) none of the above
C
The 1989 Loma Prieta earthquake: A) had a surface rupture of 400km B) was a magnitude 5.0 on the Richter scale C) had an epicenter near Santa Cruz D) all of the above
C
The Ring of Fire, which has a high hazard of earthquakes, tsunami, and explosive volcanic eruptions, is primarily defined by what type of plate boundary? A) divergent B) convergent collisional C) convergent subduction D) transform
C
The San Andreas Fault marks what kind of plate boundary? A) Convergent B) Divergent C) Transform D) Compound
C
The difference between the Moment Magnitude (Mw) scale and the Mercalli Intensity (MMI) index is that: A) each earthquake had only one MMI and multiple Mw measurements B) MMI and Mw can both be vary widely for an individual earthquake, depending on the depth of the earthquake's focus C) Mw is an absolute measurement based on energy released in the earthquake D) MMI is used widely by engineers and scientists because of its reliability in accurately recording the absolute size of an earthquake
C
The major destruction to the city of San Francisco in 1906 was due to: A) ground shaking on bay mud B) ground shaking on rock C) fire D) landsliding
C
The order of earthquake wave arrival at a seismograph station is A) surface, S, P B) surface, P, S C) P, S, surface D) P, surface, S
C
Which of the following conditions results in the greatest hazard of mass wasting? A) frequent precipitation; low slope; consolidated material B) infrequent precipitation; high slope; consolidated material C) infrequent precipitation; high slope; unconsolidated material D) infrequent precipitation; low slope; unconsolidated material
C
Which type of seismic wave causes the most damage during an earthquake? A) P-waves B) S-waves C) surface waves D) they all cause the same amount of damage
C
________ are a devastating volcanic hazard that can rapidly travel more than 10 km from a volcano, but are generally confirmed to river valleys A) ash fall B) pyroclastic flows C) lahars D) earthflow
C
A earthquake-triggered tsunami is caused by _____ A) the propagation of seismic p-waves through the ocean B) the propagation of seismic s-waves through the ocean C) violent shaking in a region of shallow, confined water such as a bay D) displacement of the seafloor during earthquake rupture
D
A magnitude 7.0 earthquake on the Richter scale is how many times more powerful (or energetic) than a magnitude 4.0 earthquake? A) 3 times B) 30 times C) 1000 times D) 27000 times
D
Based on geological evidence, the volcanic hazard that poses the largest threat to cities in Cascadia such as Tacoma and Puyallup beneath Mound Rainier, is A) lava flows B) lava domes C) pyroclastic flows D) lahars
D
How can landslide deposits be recognized in a landscape? A) well-sorted, fine grained sedimentary deposits B) well sorted, coarse-grained sedimentary deposits C) fine grained igneous deposits that cooled quickly D) poorly sorted sedimentary deposits containing material of many sizes and types
D
Localities that have a high seismic risk A) also have a high seismic hazard B) have a sizable population C) also have a high tsunami hazard D) both A and B
D
Many human factors can contribute to mass wasting hazard, including A) oversteepening of hillslopes B) removing water C) removing vegetation D) both A and C
D
Plate tectonic exists on Earth because: A) the interior of the Earth is still very hot B) as it "flows", the asthenosphere "carries" the overlaying lithosphere C) rising beneath divergent plate margins, the asthenosphere melts to create new lithosphere D) all of the above
D
Plate tectonics A) is one of the most encompassing theories in geology B) explains the uplift of mountains and the opening of new ocean basins C) is the continual motion, creation, and destruction of parts of the surface of the planet D) all of the above
D
Pyroclastic flows consists of A) rocks and lava B) water, ash, and rocks C) ash and lava D) volcanic gas, ash, and rocks
D
The "Big Bend" of the San Andreas Fault is a section of the fault where A) the fault bends, creating a zone of oblique compression B) the fault bends, creating a zone of oblique extension C) the east-west oriented Transverse Ranges are uplifted by transpression D) both A and C
D
The elastic rebound theory of earthquake basically states that: A) the crust on either side of an active fault builds up elastic strain energy during an earthquake B) During an earthquake, the fault remains locked to frictional strength C) when the frictional strength of the crust on both sides of the fault that generates the seismic waves D) it is the elastic snap-back of the crust on both sides of the fault that generates the seismic waves
D
Unlike earthquake hazard, tsunami hazard often____ A) is proceeded by a warning, sometimes my multiple hours depending on your location B) is limited to a relatively narrow band of land near the ocean C) diminishes greatly after the first few minuets of the event pass D) both A and B
D
When a continental plate and an oceanic plate collide A) a deep trench forms between them B) Volcanoes form one of the two plates C) a mountain belt rises in the collision zone D) all of the above
D
Which of the following are earthquake-related hazards that directly impact the San Francisco Bay Area? A) landslides B) liquefaction C) wave amplification D) all of the above
D
Which of the following can effectively mitigate lahar hazard? A) monitors and early warning systems B) geologic mapping C) engineering to contain and control debris flows D) all of the above
D
Which of the following types of faults form in extensional tectonic settings? A) transform B) thrust C) reverse D) normal
D
Why are pyroclastic flows so often deadly? A) they follow river valleys, where people often live B) they move at speeds greater than 100mph C) they are unpredictable and very hot D) both B and C
D
What is the driving force for plate tectonic movement
Escaping heat
Elastic Rebound Theory
It's the fundamental model for earthquakes. Tectonic motion generates stress on rocks (stress is the push, pull, or shear that a material feels when subjected to a force)
Transform margins
Lithosphere is neither created nor destroyed. Rather plates are "transformed" past one another
Focus
Location within the Earth where the original rupture along a fault begins
Core
Metal iron and nickel; has a liquid outer core and a solid inner core
_____ ______ is being formed where plates pull apart from each other
New crust
Mid-oceanic ridges
Often called "spreading centers" because they form by the process of seafloor spreading where basaltic magma wells up along fractures in the lithosphere and pours out as lava onto the seafloor
____ _____ is being destroyed where plated collide
Old crust
Convergent margins
Plate boundary where two plates converge to produce chains of volcanoes, uplifted mountain belts, and deep-sea trenches. Lithosphere is commonly destroyed along convergent margins by burial back into the mantle
Epicenter
Point on Earth's surface that lies vertically above the focus - epicenter typically doesn't occur along the surface trace of the fault
"plate"
Refers to the shape of the moving sections of Earth's outer surface
Aftershocks
Release the remnant energy remaining along the partially unlocked fault plane or they release new local stresses developed in response to the main shock
Mantel
Slightly less than half the radius of the planet, 2900 km thick. Composed of rocky, crystalline minerals
Where do most earthquakes tend to be located?
The tend to be located along the edges of continents or strung out along linear trends down the middle of oceans
Lithosphere
The upper "cool and strong" layer of rock that behaves rigidly (it bends, flexes, and breaks, but does not flow easily)
Crust
Thin outer layer, about 6km thick in the oceans and about 35 km thick in the continents
Deep strong earthquakes, are commonly associated with _________ ________ _________ where two gigantic plates rub against each other along their margins
convergent plate boundaries
New lithosphere is created along divergent margins such as the 60,000 km of underwater mountain chains known as ________ ________ that circle the globe
mid-oceanic ridges
In divergent margins _____ lithosphere is _____ whereas in convergent margins _____ lithosphere is ______
new; created; old; destroyed
Along plate boundaries where an oceanic plate converges against a continental plate, the denser oceanic plate will "dive" beneath the less dense continental plate. The "diving" process is called _______ and the entire region is commonly called a ________ _______
subduction; subduction zone
The belt of earthquakes along the subducting slabs is called _________ ________
the Wadati-Benioff zone
Plate tectonics
the continual motion, creation and destruction of parts of the planet's active surface
How thick are tectonic plates?
~60 to 200km