D2l questions 6-8 Flashcards
Why was continental drift rejected?
Wegener couldn’t explain why there were floating continents, inadequate mechanism.
What are the three types of plate boundaries?
Divergent, transform, convergent
Why do the plates move?
Plates at our planet’s surface move because of the intense heat in the Earth’s core that causes molten rock in the mantle layer to move.
why do oceans form where they do?
sea floor spreading
At what type of plate boundary do very large mountains form? Why?
Convergent, Because the plates collide
What is the driving force for a volcanic eruption?
Gasses bubbling out of solution in the magma; Plate Tectonics
Why are some volcanoes more explosive than others?
Magma, viscosity, residence to flow, temperature, amount of water, composition, amount of silica in the magma,
What are the two types of seismic waves, and which type is most destructive?
Body waves, surface waves. Surface waves more destructive
Why are magnitude scales more commonly used to measure EQ strength than are intensity scales?
When using intensity scales, the intensity varies with distance from the focus. When using magnitude scales it measure the amplitude along with calibration for distance.
What determines the amount of damage that a particular earthquake will cause?
Time of day, the population density, building design, the type of sub straight structures
Why do seismic waves travel through some earth materials with higher velocities and through some materials with lower velocities?
Because the p waves are the primary waves so they have high viscosity. So the s waves are the secondary waves so they travel a lot slower.
What is the difference between absolute and relative geologic time?
Relative is places events in the order they occurred. Absolute is numerical time- actual # ratio metric dating
What causes the sudden release of energy along a fault that results in an earthquake?
Plate movement, movement in different directions, blocks are locked, elastic energy over comes friction
What are the two types of body waves, and which type is transmitted only through solids?
P and S waves; S waves
Volcanoes are most common at which type of plate boundary?
Convergent
What are the two types of body waves, and how do they move?
P and S waves; p are pressure waves, fast, high velocity. S are shear and travel like scissors, slow
What does the difference in arrival times between P and S waves on a seismogram tell us about a particular earthquake?
How far the away earthquake is.
How do we know that the outer core is a liquid?
Because the s waves only go through solids and the earthquake doesn’t feel so far away.
Even though we have no direct physical evidence from deep within the earth, how do we know so much about the properties and composition of the earth’s interior?
We look at the body waves
Why is the silica content of magma significant for volcanic eruptions?
It determines the viscosity; more = high less = low
How cans a volcanic eruption change climate?
Volcanic ashes in atmosphere makes the climate change makes colder and dryer, it makes the sun unable to go through the ash.
What comes out of a volcano during an eruption?
Volcanic ash, Magma
How and where do stratovolcanoes form?
Seductions zones; very large dangerous mountains, have eruptive cycles.
What is the greatest hazard associated with stratovolcanoes, especially for people who live some distance from the volcano?
Landslides, mudflows and lava flows
What are the two types of surface waves?
Love and Rayleigh; love move side to side Rayleigh forward rolling motion
What is a tsunami and how do they form?
A series of water waves, caused by the displacement of large volume of a body of water.
Why are tsunamis so destructive?
Large oceanic wave, generated by an earthquake, because of the high velocity on the shoreline they make a very high wave wall and floods.
What is the seismic gap method?
A section of faults that has produced earthquakes in the passed but is now quiet.
How do scientists locate the epicenter of earthquakes?
Through the p and the s waves looks at the distance between the arrival times. Also determines the distance in distance graphs.
What are the principles of relative time?
Super position, cross cutting, fossil succession.
What is the geologic time scale?
Calendar of earth’s history
What two layers, which consist of the outer part of the mantle and the crust, are most involved in plate tectonics?
the lithosphere and the asthenosphere
Why is ocean crust subducted beneath continental crust at convergent boundaries?
it is more dense
What causes the sudden release in energy that results in an earthquake, and how is this energy transmitted away from the focus of the quake?
elastic rebound and snap-back which generate seismic waves
