Earthquakes & Volcanoes Exam 1 (GEOL 1313)
Beginning with observations, identify the remaining order of operations in the cycle used to construct and validate scientific models:
1. Model construction 2. Model prediction 3. Additional observations 4. Model revision
How far away from the Earth is the Sun?
8.3 light-minutes
Oceanic lithosphere attains its maximum thickness when it is how many years old?
80 million
How fast do the tectonic plates move?
A few centimeters per year
What would you consult to predict the effect of sea-level changes on the amount of exposed land areas?
A hypsometric curve, which shows at a glance the percentage of land that lies at each elevation
What device is used to measure magnetic anomalies?
A magnetometer
What can a seismic velocity graph be used for?
A seismic velocity graph could be used to estimate the density of solid layers beneath the Earth's surface
A mid-ocean ridge is marked by...
A series of submarine volcanoes
What is a stellar wind?
A stellar wind is a stream of atoms emitted from a star during its lifetime.
What are the tectonic plates composed of?
Crust and uppermost part of mantle (lithosphere)
T or F: Our Universe is so old that there are no first-generation stars left in it.
False
T or F: The Big Bang theory states that at the instant of explosion, atoms of all major elements came into existence.
False
T or F: The Earth's magnetic field is static, as evidenced by the fact that declination never changes.
False
T or F: The Nebular Theory does not require that Keplar's Laws of Planetary Motion and Newton's Law of Gravity be true.
False
T or F: The transition from society at large holding a geocentric view to a heliocentric view was rapid (<100 years)
False (It was several centuries)
T or F: The expanding universe theory is supported by the fact that all galaxies exhibit a blue shift.
False!! All galaxies exhibit a RED shift, which means they are traveling away from us
T or F: Planetesimals that were larger than 1 km in diameter gravitationally pulled in all surrounding dust, ice, and smaller planetesimals to become asteroids.
False. They formed into protoplanets not asteroids
T or F: Iron is the most abundant element in the Earth's crust.
False: Iron is the most abundant element on Earth but it is largely differentiated into the Earth's core. It only makes up ~6% of the Earth's crust.
T or F: Vertical fractures (fracture zones) run parallel to mid-ocean ridges.
False: They are perpendicular (right angle) to ridges
T or F: The expanding universe theory contends that galaxies are moving away from the Earth and from each other at a very low velocity.
False; HIGH velocity movement, not low
T or F: Plates may consist of both ocean floor and continental crust, but never JUST oceanic or continental crust.
False; Plates can consist of both oceanic and continental crust, or they can also be composed solely of oceanic crust
T or F: Asthenosphere consists of the lower, middle, and upper mantle, and is defined as mantle material that is cooler than 1280°C.
False; asthenosphere is WARMER than 1280°C
T or F: A fifth-generation star would have a smaller proportion of heavier elements than would a second-generation star.
False; fifth-generation star would have a LARGER proportion of heavier elements because more have been created by other supernovae
T or F: The Sun accounts for almost 50% of the Solar System's mass.
False; it accounts for 99.8% of the mass in the Solar System
T or F: New oceanic crust is ultramafic in composition
False; it is mafic
T or F: The Big Bang is the explanation for how our Solar System developed.
False; it is the explanation for how our universe began, not our solar system
T or F: The Big Bang occurred less than 13 million years ago.
False; it occurred 13 BILLION years ago
Which elements make up most of the mass of the whole Earth?
Iron, oxygen, silicon, and magnesium
Plate movement is influenced by...
Mantle convection, slab pull/ridge push
Which is more dense, continental or oceanic crust?
Oceanic
What separates the crust from the mantle?
The Moho
Is the asthenosphere part of the mantle or the core?
The mantle
What evidence did Wegener gather for his continental theory before he died?
The matching fit of the outline of some of the continents, evidence of similar paleoclimates in belts across Pangaean latitudes, and the matching of the distribution of similar fossils across oceans
What is sonar?
The method of sending pulses of sound waves down through the water and measuring the time it took for the sound to bounce off the seafloor and return to the receiver.
Geologists call a region where three plates meet a _____?
Triple junction
T or F: An accretionary disk eventually grows hot and massive enough to become a protostar, then a star.
True
T or F: Bathymetric maps show the following features of the sea floor: long, linear ridges; broad flat abyssal plains; fracture zones; elongate deep trenches; seamounts and submarine volcanoes
True
T or F: Continents passively ride along as the sea floor spreads.
True
T or F: Earthquakes with depths in excess of 500 km occur at subduction zones, where cold, dense lithosphere is pulled into the mantle.
True
T or F: Energy sources internal to the earth (conduction and convection) are much less than those external to the earth (radiation from sun).
True
T or F: Heat transport processes (convection) and gravity (ridge push, slab pull) provide the driving mechanisms of plate tectonics.
True
T or F: The explosive nature of the eruption generated a nuée ardente that raced down the mountain and engulfed the city of St. Pierre.
True
T or F: The interior of Earth differentiated into a nickel-iron core and a stony (silicate) mantle.
True
T or F: The paleomagnetic record is preserved in stripes of rock parallel to the mid-ocean ridge.
True
What are Magnetic reversals?
changes in the direction of the flow of molten iron in the Earth's outer core.
What is the asteroid belt?
the asteroid belt is a region of solid objects between the orbits of Jupiter and Mars
Trenches are usually found at which type of boundaries?
Convergent (subduction zones)
Aside from the Earth, the terrestrial planets are
Mars, Mercury, and Venus
What are abyssal plains?
The abyssal plains are broad, deep regions that sit 4 to 5 km below sea level
What does radiometric dating determine?
The age of oceanic crust
What is polar wander?
The apparent movement of the poles through time.
What is the Asthenosphere?
The upper mantle warm enough to have a small degree of partial melt, which allows it to flow slowly.
Which statement about the 1902 eruption of Mount Pelée is FALSE:
There were no precursors to the 1902 eruption of Mount Pelée.
What are mantle plumes?
They are created when hot rock rises up from the deep mantle and creates melting at the base of the lithosphere and are a possible cause of hot spots
T or F: The composition of the giant (Jovian) planets is mainly gas and "ice."
True
What are volatile materials?
Volatile materials are gases that exist at the Earth's surface, such as hydrogen, helium, methane, ammonia, water, and carbon dioxide
What explains the creation of the Hawaiian islands?
a hot spot currently sitting under Hawaii and the Pacific Plate moving across it in a northwesterly direction.
What are refractory materials?
refractory materials are those that melt at high temperatures.
How many major tectonic plates are there?
12
How long did it take for the surface of the earth to develop?
2 Billion Years (Ga)
How old is the Earth?
4.5 Billion Years (Ga)
Oceanic crust is covered in what?
A thin blanket of sediment that thickens away from the ridge axis.
What is advection?
Advection occurs when a hot fluid, like magma, moves into a cooler body carrying its heat with it and heating up the adjacent body.
Was the expanding Universe theory developed before or after the Big Bang Theory?
After
Some magma generated during seafloor spreading spills out to produce a new layer of seafloor called _____.
Basalt
Where is the Continental crust thinnest?
Beneath zones of stretching, called rifts
What is conduction?
Conduction is the process by which heat energy moves along a body, as atoms vibrate against their neighboring atoms and cause them to vibrate as well.
Continental mountain ranges such as the Alps and Appalachians are the result of what?
Continental collision
Which is older, continental crust or oceanic crust?
Continental crust
What is convection?
Convection occurs when heat is transferred from one place to another; the increase in temperature causes a decrease in density that often causes the warm, low-density material to become buoyant and rise
What causes the Earth's magnetic field?
Convection of the liquid iron alloy of the outer core generates the Earth's magnetic field.
What do you call the difference/offset between magnetic north and geographic north?
Declination
Linear mountains and valleys are a distinctive feature of this type of plate boundary:
Divergent (rifting of continents). Example: Basin and Range province in USA
T or F: Continental crust is continuously being produced and destroyed.
FALSE! Oceanic crust is continuously being produced and destroyed.
T or F: Conduction is the energy transport mechanism that occurs when an increase in temperature creates a decrease in density, causing the warm, less-dense material to rise.
False
T or F: Hazard and risk are interchangeable terms
False
T or F: Lithosphere and asthenosphere have the same physical properties; they are both rigid.
False
T or F: Lithosphere is more mafic than asthenosphere.
False
T or F: Our Sun is the only star we know of that has planets associated with it.
False
T or F: The only two planets with moons are the Earth and Jupiter.
False; most planets have moons
T or F: Continents have retained the same size and shape throughout Earth's history.
False; they have merged or split in the past
T or F: Dense regions of a nebula pull in surrounding material and therefore rotate slower.
False; they rotate faster as they grow in mass and density
What process ignited the first true stars and illuminated the universe?
Fusion reactions
Lithosphere consists of the crust and the upper mantle, and behaves like a ____ layer that ____
Hard layer that breaks and bends
Differentiation of large planetesimals and protoplanets is caused by what?
Heat created by the transformation of kinetic energy from collisions into thermal energy. During collisions, kinetic energy transforms into thermal energy (heat), which drives differentiation. Therefore, differentiation can be caused by collisions, but the term does not refer to collisions proper
The earliest nebulae to form in the Universe were made almost entirely of which 2 elements?
Hydrogen and helium
Why is the earth habitable?
It lies within the habitable zone of the Solar System
What did Johannas Kepler observe that supported the heliocentric model?
Johannes Kepler's observed that planets follow an ELLIPTICAL orbit.
Based on "Ring of Fire", identify the types of effects that accompanied the eruption of Mount St. Helens in 1980.
Lahars, pyroclastic flow, ash deposits, formation of eruption column
Are crustal rocks more or less dense than the Earth's average density?
Less dense; Crustal rocks have a density between about 3 and 5 g/cm3, well below the Earth's average density
Based on the "Ring of Fire", identify 3 types of damage that accompanied the 1989 Loma Prieta Earthquake in San Francisco.
Liquefaction, fire, bridge collapse
Is our Sun a high-mass or low-mass star?
Low-mass
Which of the Earth's layers accounts for most of the volume of the Earth?
Mantle
The heat flow through the ocean floor is greatest at...
Mid-ocean ridges
Is our Sun a first generation star?
No; it is likely third or fourth generation
(THIS WILL BE ON THE TEST!!!) The shape of the Earth can best be described as ____________.
Oblate spheroid
Whenever plates converge, what is ALWAYS the subducting plate?
Oceanic
What were the precursors to the 1902 eruption of Mount Pelee?
Precursors to the eruption included earthquakes, release of steam and gases (ie., sulfur), light ashfall, migration of animals off the mountain, and formation of a boiling summit lake.
Stars begin as...
Protostars, which fire up when they collapse and become denser & hotter
How can we detect density changes within the Earth?
Seismic-wave VELOCITY can be used to detect density changes. The waves travel at different speeds depending on the density of material
The Earth's magnetic field is distorted by _______, making it non-spherical
Solar wind
What is Stellar nucleosynthesis?
Stellar nucleosynthesis is the process by which stars create the heavier elements.
The volcano Mount Pelée results from subduction of which two plates?
Subduction of the South American plate under the Caribbean Plate.
Plate tectonics theory was widely accepted by scientists by what decade?
The 1960's
The two most common gases of the Earth's atmosphere, and their percentages, are
The Earth's atmosphere consists of 78% nitrogen and 21% oxygen, with minor amounts of argon, carbon dioxide, neon, methane, ozone, carbon monoxide, and sulfur dioxide.
What is the Earth's average density?
The Earth's density is a little over 5 g/cm3.
What is the Oort Cloud?
The Oort Cloud is a vast region of icy debris beyond the heliosphere, held by the Sun's gravity
San Francisco is located along which fault?
The San Andreas Fault
Which of the following lines of evidence for continental drift/plate tectonics was found AFTER Wegener published his theory?
The existence of mid-ocean ridges, where seafloor spreading starts
What is the geothermal gradient?
The rate of change in temperature with depth in the Earth. Although the temperature may increase with increased depth, the rate of change actually decreases with depth. The average rate of change is about 25°C per kilometer in the upper crust. Temperatures at the mantle-core boundary are approximately 3,500°C (not 5,500°C).
What is inclination?
The tilt of a magnetic needle changes with latitude to reflect the angle at which magnetic field lines enter the Earth
T or F: Lithosphere consists of the crust and the upper mantle, and behaves like a hard layer that breaks and bends.
True
T or F: Passive margins do not occur at plate boundaries.
True
T or F: Plates shift the continents around as they move, so Earth's surface is constantly changing.
True
T or F: Some magma generated during seafloor spreading erupts from submarine volcanoes.
True
T or F: The Big Bang began with all matter and energy concentrated in an infinitesimally small point.
True
T or F: The bimodal density of Earth's crust results from plate tectonics, which yields oceanic crust that is denser than continental crust.
True
T or F: The center material of our Solar System's protoplanetary disk developed into the Sun, while the series of surrounding dust, gas, and ice rings became planets.
True
T or F: The asthenosphere supports the lithosphere
True: It supports the lithosphere, rather than being part of it, colliding with it, or subducting under it.
Which feature traps cosmic rays and shields life on the Earth from excessive radiation?
Van Allen belts
What is largely responsible for creating Earth's atmosphere?
Volcanic eruptions, planet outgassing, and comet collisions are largely responsible for creating the Earth's atmosphere.
The expanding Universe theory raises the question of?
When the expansion began
The Himalayas are growing because
a continental plate is colliding with another continental plate there.
The Big Bang theory states that
all matter in the Universe was once confined to a single point.
Why did Plate tectonics theory take decades to be accepted?
because Wegener couldn't explain how continents moved.
What composes the lithosphere?
crust and upper mantle
Over time, the Earth's interior separated into layers according to density, as shown here, through a process called...
differentiation
Atoms that are heavier than iron are generally produced by
explosions of supernovas
By far the most common elements in the Universe and in our Solar System are
hydrogen and helium
Studies of interplanetary space have indicated that...
interplanetary space is much denser than interstellar space.
The Earth is round because...
its interior rock is warm enough to flow slowly in response to gravity, which creates a spherical shape that permits the force of gravity to be the same at all points on its surface.
The Big Bang theory explains that
nebulae condensed and heated to become spinning accretionary disks, then protostars, then stars.
The center of a mid-ocean ridge is where
new oceanic lithosphere is being created.
The global occurrence of earthquakes reveals that they usually occur...
on the boundaries of plates or at hot spots.
The Earth's magnetic field is generated in the...
outer core
Magnetic anomalies are...
places where the magnetic field strength is either greater or less than the expected strength.
What occurs at Boundaries between the Earth's layers?
places where there is an abrupt change in the density of rock.
The heavier elements on the Earth (those with atomic numbers greater than 5) are formed by what?
stellar nucleosynthesis during the life cycles of existing stars.
What is the Kuiper belt?
the Kuiper Belt is a diffuse ring of icy objects that once formed the outer reaches of the protoplanetary disk
Earthquakes but not volcanoes occur in San Francisco because
two plates are moving past each other there. (transform boundary)