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277 Cards in this Set
- Front
- Back
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the three largest earthquakes in the continental United States have occurred in the _____ area
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New Madrid; they occurred in December, January, and February and did a lot of damage but there were not very many people there to see it. Today an earthquake in this area would likely kill thousands
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a sudden motion or trembling in the earth caused by the abrupt release of slowly accumulated strain
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earthquake
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Earthquakes can be caused by five things? Which of these five is the most common?
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(1.) volcanic activity, (2.) meteorite impacts, (3.) undersea landslides, (4.) explosions of nuclear bombs, (5.) MOST COMMON -- the movement of Earth across a fault
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a fracture in the Earth's crust across which the two sides move relative to each other
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fault
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the study of earthquakes
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seismology
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an instrument used to detect earthquake waves
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seismometer
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an instrument used to record earthquake waves
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seismograph
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seismographs capture the movement of Earth in three components; what are they?
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north-south, east-west, and vertical
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How does a seismograph work?
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One part stays as stationary as possible while Earth vibrates; a heavy mass fixed by inertia in a frame that moves with the Earth, leading to differences between position of the frame and the mass to be recorded digitally
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p-waves are also known as _____ waves
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compression
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s-waves are also known as _____ waves
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shear
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although the p- and s-waves originate and move away from a fault rupture at the same time, the _____ is faster so it is recorded first by the seismometer
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p-wave
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waves from large earthquakes can pass _____ and therefore be recorded where?
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through the Earth; all around the world
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True or false: Waves follow straight paths through the Earth as they encounter different layers.
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false
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Waves do not follow straight paths through the Earth but change _____ and _____ as they encounter different layers
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velocity; direction
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How do we know that the outer core is liquid?
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When waves hit the outer core, the velocity drops considerably and s-waves stop completely at the outer core. P-waves, on the other hand, transmit through each other (think of the people) ++ EXPAND ON THIS NOTECARD
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_____ says that you get a refraction of a wave when you go through layers of different densities and that wave keeps refracting until it comes back up to the surface, as in the shape of a "u"
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Schnell's law
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with regard to waves, _____ refers to displacement and is how big the wave is
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amplitude
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with regard to waves, _____ refers to the distance between successive waves
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wavelength
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with regard to waves, _____ refers to the time between waves
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period
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with regard to waves, _____ refers to the number of waves in one second (1/period)
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frequency
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Seismic waves come in two families: those that can pass through the entire Earth, known as _____ and those that move near the surface only, known as _____
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body waves; surface waves
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Between body waves and surface waves, which are faster?
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Body waves; they have short periods and are most energetic near the hypocenter
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p-waves and s-waves are both types of _____ waves
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body
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What are the two types of body waves?
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p-waves and s-waves
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an s-wave is also known as a _____ wave
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shear
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_____ waves are the fastest of all waves and are always the first to reach a recording station, hence their name
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primary/p-waves
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_____ waves move in a _____ motion involving alternating pulses of compression and extension, like a wave through a Slinky
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primary; push-pull
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_____ waves can travel through solid, liquid, or gas and their velocity depends on the _____ and _____ of the substance they are traveling through
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primary/p-waves; density; compressibility
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_____ waves are the second to reach a recording station; they exhibit a _____ motion involving _____ or shaking particles at right angles to the wave's path
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secondary/s-waves; transverse; shearing
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_____ waves travel only through solids and are reflected back or converted if it reaches _____; their velocity depends on the _____ and _____ of the substance
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secondary/s-waves; liquid; density; resistance to shearing
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there is a velocity of about _____ km/sec for p-waves through granite
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4.8
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there is a velocity of about _____ km/sec for an s-wave through granite
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3.0
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the up-and-down and side-to-side shaking done by _____ waves cause extensive damage to buildings
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secondary/s-waves
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_____ waves travel near the Earth's surface and created by body waves disturbing the surface
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surface
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Surface waves have a _____ period than body waves and carry energy further
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longer
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Love waves are a type of _____ waves
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surface
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Rayleigh waves are a type of _____ waves
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surface
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_____ are a type of surface waves that are similar in motion to s-waves, but move _____ in a horizontal plane, travel _____ than Rayleigh waves, and do not move through air or water
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Love; side-to-side; faster
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_____ waves are a type of surface waves that include a _____-rotating, _____ motion that produces horizontal shaking that feels like a rolling boat at sea
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Rayleigh; backward; ellipitcal
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Regarding surface waves, _____ waves travel faster but _____ travel great distances
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Love; Rayleigh
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More energy is released by Rayleigh waves when the hypocenter is _____ to the surface
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close
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p-waves travel about _____ times faster than s-waves
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1.7
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the further you go from the hypocenter, the _____ the lag time of s-waves behind p-waves
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greater
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you need the distance of an earthquake from _____ stations to pinpoint the location of an earthquake; basically, circles are drawn around each station for an appropriate distance from the station and the earthquake's location is at _____. This method is most reliable when the earthquake is _____ the surface
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three; the intersection of the circle; near
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In the _____ or (more preferably) the _____, there is a relationship between the distance from the station and the maximum amplitude of the s-wave and the magnitude of the earthquake
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Richter; local magnitude earthquake scale
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the _____ was the first to measure magnitude
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Richter scale
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the _____ was devised in 1935 to describe the magnitude of shallow, moderately-sized earthquakes located near Caltech seismometers in southern California
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Richter scale
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the Richter scale was developed to describe the magnitude of _____, _____-sized earthquakes
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shallow; moderately
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the Richter scale does not work well for _____ or _____ earthquakes. Why?
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distant; large; because short-period waves do not increase amplitude for bigger earthquakes
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True or false? All magnitude scales are not equivalent.
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true
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Two other magnitude scales are the _____, which uses the amplitudes of p-waves with 1 to 10-second periods, and _____, which uses Rayleigh waves with 18 to 22-second periods
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body wave scale; surface wave scale
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Two other magnitude scales are the body wave scale, which uses the amplitudes of _____ with 1 to 10-second periods, and the surface wave scale, which uses _____ with 18 to 22-second periods
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p-waves; Rayleigh waves
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Larger earthquakes radiate _____ energy at _____ periods not measured by the _____ or _____
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more; longer; Richter scale; body wave scale
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Richter scale and body wave scale significantly _____ magnitudes of earthquakes far away or large
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underestimate
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the magnitude scale goes up _____
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exponentially
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the best way to measure magnitude is _____
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seismic moment/the moment magnitude scale
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with regard to the moment magnitude scale, a _____ is calculated using rocks' shear strength times rupture area of fault times displacement (slip) on the fault and -- measures the amount of strain energy released by movement along the whole rupture surface --
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seismic moment
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a seismic moment measures the amount of _____ released by movement along the whole rupture surface and is _____ accurate for big earthquakes
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strain energy; more
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the _____ uses seismic moment in a mathematical formula
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moment magnitude scale
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the best way to measure magnitude
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seismic moment
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seismic moment is the best way to measure _____
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magnitude
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fault-rupture _____ and _____ influence seismic wave frequency
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length; duration
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fault-rupture length and duration influence seismic wave _____
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frequency
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a short rupture and duration results in _____ frequency seismic waves
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high
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a long rupture and duration results in _____ frequency seismic waves
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low
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True or false? Seismic wave frequency influences damage.
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true
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_____ frequency waves cause much damage at the epicenter but _____ with distance from epicenter
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high; die out quickly
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_____ frequency waves travel great distance from the epicenter and do the most damage _____
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low; farther away
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buildings are designed to handle _____
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vertical forces
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_____ during earthquakes can do massive damage to buildings
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horizontal shaking
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Where does the word "volcano" come from?
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The island of Vulcano in the Mediterranean Sea, where people believed Vulcano was the chimney of the forge of Vulcan, the blacksmith of the Roman gods.
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90% of volcanism is associated with _____
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plate boundaries
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80% of volcanoes occur at _____ and about 10% occurs at _____; the remaining 10% of volcanism occurs above _____
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spreading centers; subduction zones; hot spots
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it is best to understand volcanoes in the context of _____
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plate tectonics
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variations in magma's _____, _____ (_____), and _____ determines whether eruptions are peaceful or explosive
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chemical composition, ability to flow (viscosity), gas content and volume
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_____ combine to form _____, which combine to form _____
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elements; minerals; rocks
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different compositions of magma result in different _____ rocks
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igneous
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mineral formation in magma is called
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crystallization
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crystallization is _____
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mineral formation in magma
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there are _____ naturally occurring elements, and _____ make up 99.23% of Earth's crust
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92; 12
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_____ and _____ are by far the most abundant in the Earth's crust, forming the _____
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oxygen; silicon; SiO4 tetrahedron
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_____ and _____ make up mafic oceanic crust
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magnesium and iron
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magnesium and iron make up _____ crust
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mafic oceanic
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_____ and _____ make up felsic continental crust
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silicon and oxygen
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silicon and oxygen make up _____ crust
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felsic continental
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What three things will eventually cause a rock to melt?
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(1.) lowering pressure, (2.) raising temperature, (3.) increasing water content
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What three things will eventually cause a rock to melt?
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(1.) lowering pressure, (2.) raising temperature, (3.) increasing water content
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Lowering pressure, raising temperature, and increasing water content will cause _____
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rock to melt
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The most common way to melt rock is _____
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decompression melting
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What is the most common way to melt rock?
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decompression melting
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What effect will s-waves have on pillars? Why?
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An s-wave would cause a pillar to shatter to pieces because it is moving horizontally and buildings/pillars are not designed to handle horizontal shaking
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_____ cause more damage. Why?
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s-waves; they shake horizontally and most buildings are not designed to handle horizontal shaking
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_____ is what we use to measure ground motion during earthquakes
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acceleration
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at a boundary, a wave will _____ or _____
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reflect; refract
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a wave refracts _____ in slower material
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down
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a wave refracts to _____ in faster material
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shallower material
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_____ permit us to find depth to crust-mantle boundary
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curved paths (under the surface)
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close to the earthquake, paths through _____ arrive first
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the crust
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farther away from an earthquake, paths through _____ arrive first
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the faster mantle
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_____ speed up and down as they travel through the Earth depending on the material they are traveling through
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p-waves
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with regard to seismic waves within the Earth, faster velocities indicate _____
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denser materials
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with regard to seismic waves within the Earth, _____ indicate denser materials
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faster velocities
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_____ neutralizes s-waves
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the core
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How do we know that there is a density core between the core and other layers of the Earth?
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because of the bent waves; if there are no s-waves, we can infer that they have to go through a liquid, in which case they do not survive
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states that sediments are originally deposited in horizontal layers
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law of original horizontality
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the law of original horizontality states that
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sediments are originally deposited in horizontal layers
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states that in undeformed sequences of sedimentary rock layers, each layer is younger than the layer beneath it and older than the layer above it
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law of superposition
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the law of superposition states that
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in undeformed sequences of sedimentary rock layers, each layer is younger than the layer beneath it and older than the layer above it
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Why is the law of original horizontality important?
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if the layers are not horizontal, you can surmise that something caused them to move
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young rocks are on _____ whereas older rocks are on _____
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top; the bottom
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the law of superposition refers to rocks of which type?
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sedimentary
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states that sediment layers are continuous and end only (1.) against a topographic high, (2.) by pinching out from lack of sediment, or (3.) by graduational change from one sediment to another
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law of original continuity
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the law of original continuity states that
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sediment layers are continuous and end only (1.) against a topographic high, (2.) by pinching out from lack of sediment, or (3.) by graduational change from one sediment to another
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true or false? understanding fault offsets can have financial rewards
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true, such as if an ore-bearing unit exists in two different places on either side of a fault
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complex zones of breakage with irregular surfaces, can be many miles wide and long and thin or narrow
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faults
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faults are
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complex zones of breakage with irregular surfaces, can be many miles wide and be long and thin or narrow
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in the process of _____, brittle lithospheric rocks fracture and crack
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jointing
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a large stress differential on either side of a fracture results in movement, leading the fracture to become a _____
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fault
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_____ and _____ are used to describe the location in 3D space of a deformed rock layer
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strike; dip
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the angle of inclination from horizontal of tilted layer
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dip
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the compass bearing of the horizontal line in a tilted layer
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strike
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the angle of inclination from horizontal of a tilted layer
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dip
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the compass bearing of a horizontal line in a tilted layer
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strike
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where two plates meet
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plate boundary
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_____ occur on plate boundaries and where plate boundaries separate
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faults
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_____ is referred to with degrees while _____ is referred to with a direction
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dip; strike
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seismic waves radiate outward from the _____
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hypocenter
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what causes most earthquakes?
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faults
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on what kind of plate boundary do we find normal faults?
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divergent boundary
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on what kind of plate boundary do we find reverse and thrust faults?
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convergent boundary
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on what kind of plate boundary do we find strike-slip faults?
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transform boundaries
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at a divergent boundary, we find _____ faults
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normal
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at a convergent boundary, we find _____ faults
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reverse/thrust
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at a transform boundary, we find _____ faults
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strike-slip
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where the dominant force is extensional (pulling apart/exterior), a _____ fault occurs when the hanging wall moves down relative to the footwall, and a zone of _____ results
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normal; omission (because things are spreading apart and there is like an exess area)
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where the dominant force is compressional (pushing together), a _____ fault occurs when the hanging wall moves up relative to the footwall, and a zone of _____ results
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reverse; repetition (because there is more than one layer there)
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_____ faults are dominated by horizontal movement
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strike-slip
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strike-slip faults are dominated by _____ movement
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horizontal
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when straddling a fault, if the right-hand side has moved towards you, it is a _____-lateral fault
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right
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when straddling a fault, if the left-hand side has moved towards you, it is a _____-lateral fault
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left
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the San Andreas fault is a _____-lateral fault
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right
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with regard to earthquakes, stress builds up until _____ occurs at a weak point and propagates along fault surface
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rupture
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the point where a rupture first occurs is known as the _____ or _____
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hypocenter; focus
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the point directly above the hypocenter on the surface is the
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epicenter (think epidermis/skin)
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a fault rupture is a _____ of events, with the largest one referred to as _____
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the earthquake
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a _____ is a series of events with the largest one referred to as the earthquake
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fault rupture
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within a fault rupture, smaller events preceding the earthquake are known as
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foreshocks
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within a fault rupture, smaller events after the earthquake are known as
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aftershock
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the point at which a fault ruptures the surface is known as a _____
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fault scarp
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true or false? earthquakes do not rupture along clean, straight lines but with several breaks that stop and start and bend
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true
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name four things that could cause earthquakes
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volcanic eruptions, landslides, meteoroid impacts, explosions
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continental strike-slip faults can produce _____ but _____ earthquakes
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large; shallow
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continental collisions produce _____ _____
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large earthquakes
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continental rifts cause _____, _____-sized earthquakes along _____ faults
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shallow; moderate; normal
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just as waves have natural frequencies and periods, so do _____
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buildings
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the period of swaying for buildings is about _____
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0.1 second per story
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building materials affect building periods; flexible materials like wood and steel result in _____ periods of shaking whereas stiff materials like brick and concrete result in _____ periods of shaking
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longer; shorter
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the _____ determines which buildings and which ones will not
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frequency content
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as something goes from a faster medium to a slower medium, _____ increases
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amplification
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the velocity of a seismic wave depends on the _____
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material it is moving through
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the _____ of a seismic wave depends on the material it is moving through
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velocity
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a seismic wave moves _____ through hard rocks and _____ through soft rocks
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faster; slower
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a seismic wave moves faster through _____ rocks and slower through _____ rocks
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hard; soft
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when waves pass from harder to softer rocks, they _____
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slow down
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waves slow down when they pass from _____ to _____ rocks
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harder; softer
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in order to carry the same amount of energy, you have to _____ the _____ of waves
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increase; amplitude
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shaking tends to be _____ in basins, valleys, and reclaimed wetlands
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stronger
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_____ was developed to quantify what people feel during an earthquake
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Modified Mercalli Scale
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_____ assesses an earthquake's effect on people and buildings
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Modified Mercalli Scale
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_____ was used for earthquakes before instrumentation or for current earthquakes in areas without instrumentation
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Modified Mercalli Scale
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earthquake intensity refers to what?
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what we feel during an earthquake
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before an earthquake, it is a good idea to visualize what may fall and to _____ these items and to _____ that offer protection
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anchor; locate safe spots
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the best course of action to follow during an earthquake is to _____ and if you are inside, stay inside; if you are outisde, stay outside
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duck, cover, and hold
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the _____ fault is being investigated in depth by means of a borehole drilled across the fault with instruments that collect data on earthquakes as they occur
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San Andreas
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the combined probability of a major earthquake in the San Francisco area before 2032 is over _____ percent
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60
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true or false? predictions based on the past activity of a fault are problematic
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true
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magma can be made more thick because as it rises to the surface, it can incorporate pieces of the rock through which it passes called _____
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inclusions
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A quality of the seismic wave called the _____ can be used to distinguish parts of the lower mantle
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shear wave velocity
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The study of this earthquake was one key step in development of the theory of plate tectonics
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Great Alaskan Earthquake of 1964
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moving magma and volcanic fluids trigger _____, volcanic _____
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shallow; earthquakes
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rising magma and volcanic gases in volcanoes exert pressure, which causes _____, which triggers _____
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rocks to break; earthquake
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melting temperature _____ with increasing pressure, so a pressure decrease on an already hot rock can initiate _____
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rises; melting
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magma contains dissolved gases; there is more dissolved gas as pressure _____ and temperature _____
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increases; decreases
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_____ is the most abundant dissolved gas in magma
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water
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what is the most abudnant dissolved gas in magma?
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water
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as magma rises and pressure decreases, dissolved water becomes _____
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steam bubbles
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mafic magma has a _____ water content and is therefore responsible for more peaceful, safe eruptions
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lower
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felsic magma has a _____ water content and _____ viscocity and is therefore responsible for violent, dangerous eruptions. Why?
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higher; high; because many steam bubbles form and they cannot escape through thick magma so it explodes
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mafic magma is associated with _____ eruptions
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peaceful
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felsic magma is associated with _____ eruptions
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dangerous
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_____ of our water came from volcanoes
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99.9%
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when water is present, the melting curve shifts to the _____ because water provides an additional agent to break chemical bonds
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left
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rocks melt at a _____ temperature if water is present
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lower
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rocks melt at a lower temperature if _____ is present
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water
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Adding water causes something to melt at a lower temperature. Why?
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the water molecules interfere with other molecules
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internal resistance to flow
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viscosity
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viscosity is
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internal resistance to flow
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something with low viscosity is _____
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more fluid
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something with high viscosity is _____
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thicker
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water and melted ice cream have a _____ viscosity
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lower
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honey and toothpaste have a _____ viscosity
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higher
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something with a higher temperature results in a _____ viscosity
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lower
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something with a _____ temperature results in a lower viscosity
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higher
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something with more SiO4 has a _____ viscosity
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higher
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something with _____ SiO4 has a higher viscosity
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more
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is something with more SiO4 thicker or thinner?
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thicker (because more SiO4 results in a higher viscosity, and something with high viscosity is thicker)
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Why does something with more SiO4 have a higher viscosity?
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it has to do with the type of bonding; primarily covalent bonds
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a higher viscosity results in _____ eruptions. Why?
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more explosive; because it is thicker, bubbles do not get out as much and therefore explode
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something that is more viscous is _____ to flow and _____ gas
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more difficult; traps
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something that is less viscous is _____ to flow and _____ gas
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easier; releases/allows gas to escape
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adding water to magma does what?
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lowers the temperature of the magma
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at spreading centers, you would expect to see
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abundant (but peaceful) volcanism
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you would expect to see abundant (but peaceful) volcanism at
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spreading centers
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Why would you expect to see abundant volcanism at a spreading center?
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at spreading centers, plates pull apart and the asthenosphere rises and melts under low pressure; low SiO2, low viscosity Mafic magma allows easy escape of gases and therefore peaceful eruptions
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spreading centers sit above the hot _____
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asthenosphere
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at subduction zones you would expect to see
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violent eruptions
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you would expect to see violent eruptions at
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subduction zones
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You would expect to see violent eruptions at subduction zones. Why?
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Magma is generated by the partial melting of the subducting plate with water in it and melts the overlying crust to produce magma of variable composition, leading to a decrease in temperature and an increase in SiO2, water content, viscosity (and therefore making more violent eruptions)
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a scoria cone is _____, meaning the hazard level is _____
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steep; higher
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this type of volcano has medium viscosity, medium volatiles, and small volume
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scoria cone
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scoria cones have a _____ viscosity, _____ volatiles, and _____ volume
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medium; medium; small
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these volcanoes have a great width compared to height
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shield volcanoes
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the largest volcanic events known on Earh
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flood basalts
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_____ are low conical hills (also known as _____) of mafic to felsic pyroclastic debris built up at a volcanic vent
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scoria cones; cinder cones
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can have summit crater with lava lake during eruption
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scoria cones
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form during eruptions lasting hours to several years
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scoria cones
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after eruptions cease, _____ usually have central vent of hard lava with softer layers of pyroclastic debris; erosion may eventually leave only central vent standing above countryside as _____
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scoria cones; volcanic neck
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these types of volcanoes have low viscosity, low volatiles and large volume
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shield volcanoes
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shield volcanoes have _____ viscosity, _____ volatiles, and _____ volume
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low; low; large
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_____ are comprised of thousands of layers on top of each other that come together to form a very broad, gently sloping volcano
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shield volcanoes
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_____ have a great width compared to height
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shield volcanoes
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Mauna Loa in Hawaii is an example of what type of volcano?
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shield volcano
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The world's most active volcano is
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Kilauea
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a volcano composed of different materials (pyroclastic flows, mudflows, lava, etc.)
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composite volcano
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Mount St. Helens is an example of what type of volcano?
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volcanic dome
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there is 1 earthquake approximately every _____ seconds
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30
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a quantitative value related to the amount of energy released along a fault
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magnitude
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a qualitative measure of what people felt at various distances
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intensity
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_____ remains the same no matter where you are, but the _____ will change
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magnitude; intensity
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intraplate earthquakes of the _____ US can be felt over much larger areas relative to earthquakes of similar magnitude in _____
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central; California
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a system of deep faults covered in a very thick blanket of soft sediments and included with large bodies of igneous rock
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reelfoot rift
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the source for most of the New Madrid region's significant earthquakes
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stretching apart of the Earth's crust at the Reelfoot Rift
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the major New Madrid earthquakes happened predominantly in what 2 years?
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1811-1812 (though aftershocks continued through 1817)
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a process by which
water-saturated sediment temporarily loses strength and acts as a fluid |
liquefaction
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what is liquefaction?
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a process by which water-saturated sediment temporarily loses strength and acts as a fluid
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An earthquake that happened in _____ proves liquefaction and substantiates much of the New Madrid historic record since the area is similar to the New Madrid area
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Gujarat, India
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magnitude 7 or higher earthquakes occur in the New Madrid area about every _____ years
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500
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Why do earthquakes occur in the middle of the continent in the New Madrid region?
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Reelfoot Rift
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U.S. Geological Survey forecasts _____ probability of magnitude 6-7 earthquake in the New Madrid area in the next 50 years
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90%
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LOOK OVER MITIGATION
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LOOK OVER MITIGATION
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devices used to measure vibrations
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accelerometers
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What does CNMSN stand for?
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The Cooperative New Madrid Seismic Network
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The strongest earthquake in the history of Kentucky happened where? What magnitude was it?
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in northeast Kentucky, near Sharpsburg, Bath County. The magnitude was 5.03
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What are four things that can be done to prepare for an earthquake?
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(1.) develop a home earthquake plan, (2.) prepare a disaster supplies kit, (3.) be ready when the shaking begins, (4.) know what to do after an earthquake
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What should you do during an earthquake?
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duck, cover, and hold onto the legs of the desk or table to prevent it from moving
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What are some things that should be done following an earthquake?
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Be calm, check for injuries, be ready for aftershocks, stay away from buildings, listen to firefighters and other emergency workers, watch out for hazards like broken glass, fires, and downed power lines
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most continents today have a piece of archean crust that we call the core of the continent or the _____
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craton
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Earthquake activity beneath a volcano almost always _____ before an eruption. Why?
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increases; because magma and volcanic gas must first force their way up through shallow underground fractures and passageways, and when they move they cause rocks to break or cracks to vibrate; when rocks break earthquakes are triggered
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most volcano-related earthquakes are _____ in magnitude
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small (less than a magnitude of 2 or 3)
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in 1980, a magnitude _____ earthquake shook Mount St. Helens, killing approximately _____ people
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5.1; 57 (although some may merely be still missing)
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RSAM refers to _____ measurement, an automated technique for tracking seismic energy
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Real-Time Seismic Amplitude Measurement
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earthquake activity in the Mount St. Helens area led to what?
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dome building (though it has stopped after three years of continuous growth)
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the current status of Mount St. Helens is alert level _____ or what color?
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2; orange
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true or false? Seismicity at Mount St. Helens is at its lowest level since before the eruption began in 2004, and has been so since late January 2008
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true
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Scoria cones form when
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basaltic magma contains dissolved gas
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when lava flows out of a fissure fed by dikes
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fissure eruption
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when lava spreads out and flows downhill
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lava flow
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when lava erupts into water forming rounded shapes called pillows
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pillow basalt
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what type of volcano contains solidified lava with volcanic ash and rock fragments and very viscous felsic or intermediate magma
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volcanic dome
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Ecuador is an example of what type of volcano?
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composite
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Mount St. Helens is an example of what type of volcano?
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dome
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a volcano-related topographic depression that erupts huge volume of magma, mostly as volcanic ash
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caldera
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flood basalts have a _____ viscosity, _____ volatiles, and _____ volume
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low; low; very large
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flood basalts coincide with _____
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mass exctinctions (Siberia, India)
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can indirectly have global effects as huge amounts of gases (including CO2 and SO2) are released into the atmosphere
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flood basalts
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broken up fragments of magma and rock from violent gaseous explosions, classified by size
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pyroclastic debris
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