Geo 004
4 A's of mitigation
Avoid, accept, anticipate, alter
Which describes the lithosphere?
Behaves rigidly and is brittle, "floats" on top of the asthenosphere, is solid, consists of the crust and upper mantle, NOT where earthquakes occur
Magnitude
Bigger the earthquake, the more energy emitted and more rare
The Earth's innermost layer is known as the core when considering ___ properties, but is broken into 2 layers, outer core and inner core, when discussing ___ properties.
Chemical, physical
Dip slip: Reverse fault
Compressional setting, hanging wall moves up
Volcanoes are formed at ___ .
Divergent and convergent plate boundaries
Geometrical spreading
Energy has to be spread over a large area as the distance from the source increases (think of ripples)
Dip slip: Normal fault
Extensional setting, hanging wall moves down
Normal faulting occurs when the hanging wall moves upward relative to the footwall
False
Shield volcanoes are steep-sided, symmetrical volcanic peaks built of alternating layers of pyroclastic debris capped by high-viscosity andesitic to rhyolitic lava flows.
False
Radical component
Forward and backward
Why does amplitude vary from location to location? Why do amplitudes vary from earthquake to earthquake?
Geometrical spreading, attenuation, rock type, site effects, earthquake magnitude
Super volcano
High viscosity, high volatility, very large volume
Lava dome
High viscosity, low volatility, small volume
Which characteristics describe a transform plate boundary?
Horizontal sliding plate motions, occurrence of earthquakes, and strike-slip faulting
The ___ is where an earthquake starts and the ___ is a surface point on map directly above the hypocenter.
Hypocenter, epicenter
The most peaceful eruptions are
Icelandic type eruptions
Internal heat energy
Impact of asteroids and comets, decay of radioactive isotopes, gravitational energy, differentiation into layers
Attenuation
Loss of energy with distance due to scattering and friction 1. Friction between mineral grains dissipates energy and reduces amplitude 2. The longer the wave travels, the more energy is lost (doesn't happen in cold areas) 3. Different rocks/regions have different friction properties- variable attenuation
shield volcano
Low viscosity, low volatility, large volume
After lava cools, atoms in iron-bearing minerals on the seafloor become ___ . This evidence of ___ is just one dataset supporting the theory of plate tectonics.
Magnetized in the direction of the Earth's magnetic field at that time and place, seafloor spreading
Flood basalts
Massive volume of magma, mass extinctions, low viscosity, low volatility, very large volume
Stratovolcano
Med/high viscosity, med/high volatility, large volume
Cinder (scoria) cone
Medium viscosity, medium volatility, small volume
Mechanical Layers
Physical properties, material strength
convergent plate boundary
Plates colliding (subduction zone) anything dense goes down
P waves
Primary seismic waves, Sound waves, side to side motion
What type of motion is associated with divergent plate?
Pull apart
What characteristics describe a divergent plate boundary?
Pulling apart plate motions, occurrence of earthquakes, and normal faulting
What type of motion is associated with convergent plate boundaries?
Push together
What characteristics describe a convergent plate boundary?
Pushing together plate motions, occurance of earthquakes, and reverse faulting
The primary cause(s) of death from explosive volcanic eruptions is (are) ___.
Pyroclastic flow
___ faults are commonly found at areas of plate convergence where subduction or continental collision occurs.
Reverse
Surface waves: rayleigh wave
Rolling motion, particle motion is circular
Seismic waves
Ruptures releases energy as seismic waves that pass through the earth
S waves
Secondary, up and down motion
Rock type
Sediment or soil have large amplitudes and rock have smaller amplitudes Sediment= soft, ground easily moves Bedrock= hard, ground does not easily move
Site effects
Sediment sites amplify seismic waves (liquefaction)
Several geologic phenomena are considered precursors of an impending volcanic eruption. These include ___, ground deformation, and ___.
Seismic waves, the release of gases
Evidence for plate tectonics
Shape of the continents, rocks of mountain belts, fossils, earthquake locations, volcano locations and hot spot volcanism, seafloor magnetization and age
strike-slip fault
Shearing setting, moves horizontally
Tangential component
Side to side
Volume
Size of magma chamber, more magma= more erupted material
What type of motion is associated with transform plate boundaries?
Slide past
Chemical Layers
Sorted by density, heaviest elements near center
Map design elements
Title, numeric scale, north arrow, legend, graphical scale
A majority of earthquakes occur on or near plate boundaries.
True
Hot spots have active volcanoes above them on the Earth's surface and moving plates carry the volcanoes away from their hot-spot source.
True
Strike-slip (transform) faults usually link spreading centers or connect spreading centers with subduction zones.
True
The movements of the lithospheric plates are directly responsible for the vast majority of the earthquakes, volcanic eruptions, ans mountains on Earth.
True
The rates of plate movements are comparable to those of human fingernail growth
True
The types of rock or sediment on which a structure's foundation sits are of paramount importance with respect to whether the structure will be damaged by shaking from an earthquake
True
Volcanoes tend to occur mostly along plate boundaries.
True
In addition to lava flows, volcanic processes can cause
Tsunamis, debris avalanches, lahars
Vertical component
Up and down
3 V's of volcanic hazard
Viscosity, volatiles, volume
The three Vs of volcanology are ___ .
Viscosity, volatiles, volume
Epicenter
Where seismic waves rupture, location on the surface directly above the hypocenter
Hypocenter
Where seismic waves start, location in earth where earthquakes begins
Surface waves: love waves
Zig zag motion, increase in depth there's a decrease in motion, slower than p and s waves
Slow flowing, more viscous basaltic lava commonly has a rough, blocky texture called
a'a
A caldera collapse occurs
after the magma chamber is mostly empty
Types of plate boundaries
convergent, transform, divergent
When oceanic lithosphere collides with another plate, the ___ in the process of subduction.
older, colder plate turns downward beneath the younger, warmer plate
divergent plate boundary
plates pull apart
As radioactive atoms decay, energy is
released
Viscosity
resistance to flow, higher it is the more explosive
transform plate boundary
sliding past each other