test 2 Flashcards
What are the three major components of the Earth and their features?
Surface/Crust – is made of thinner oceanic plates and thicker continental plates
Mantle – makes most of the earths diameter and is under high pressure
Core – near center and under high pressure composed of metallic iron and nickel, outer core is molten, and the inner core is solid
What are the three possible movements of plates, relative to each other?
Divergent – push away from each other
Convergent – push towards each other, when oceanic and continental plates come together oceanic plate falls under because it is thinner
Transform – plates slide against each other in opposite directions
Where are divergent plates commonly found?
Along plate boundaries
What are the three types of convergent plates?
Oceanic – Oceanic
Continental – Continental
Continental – Oceanic
What happens at a transform plate boundary?
The friction from the sliding produces faults and causes earthquakes
Name and describe types of forces that can cause the Earth material to move?
Compression – material is forced together
Tension – material pulled apart
Shear – creates horizontal movement
What is a fault? What are the four types?
A fault is movement of two beds, either vertical or horizontal
Normal fault – hanging wall moves down
Reverse fault – hanging wall moves up
Thrust fault – reverse fault with folding (bending) of hanging wall
Strike-slip fault – lateral movement
Describe the five types of folds.
Anticlines – A shape
Syncline – U or V shape
Dome – uplift in a circular area
Basin – Opposite of dome, center is downward
Monocline – mostly flat areas with only one-fold downward
What are the four basic causes of an earthquake?
Movement along faults
Activity around volcanoes
Gravitational movement of material can result in Landslides
Variety of explosions (human caused or natural)
Describe the terms hypocenter and epicenter relative to an earthquake.
The point of the earthquake is the hypocenter (including depth below surface), the earth surface above is the epicenter
How can a seismometer be used to measure an earthquake?
It records earth vibrations by showing the amount of movement as squiggles
Relative to an earthquake, what are P-waves and S-waves?
Primary waves are the result of compression moving the fasted
Secondary waves are movements perpendicular and move slower
How can we determine the location of an earthquake?
By using three stations to record the waves and triangulate them
What is the magnitude of an earthquake?
The strength of the earthquake – how much the earth shakes
Describe how the Richter scale is used to measure the magnitude of an earthquake.
A scale from 1-10 but each level is 10 times greater than the last, 3 is 10 times greater than 2
Lowest is 1 and most powerful is 10
Where are earthquakes most common?
Oceanic continental plate boundaries
The rift valley of Africa
Along mid oceanic ridges
What are the outcomes of earthquakes?
Human structures can collapse, rockslides, material can lift, settle, or slide, and under water earthquakes can cause tsunamis
What is magma?
Molten material that has come outside to earth’s surface
How and why does magma vary between solid and liquid within the Earth?
Changes in temperature and pressure
With very high pressure material stays solid, but loss of pressure may result in turning liquid
In what ways does magma change as it moves closer to the Earth’s surface?
The reduced pressure can cause partial or complete melting as it moves toward the surface
How do temperature, composition, and crystals influence the movement of magma?
Temperature
High – very liquid, below the surface
Low – thick, closer to surface
Composition
Few silicates can move easier
Water dissolved in magma can even vaporize
Presence of crystals
More crystals – slower movement
Fewer crystals – faster movement
Name and contrast the four types of volcanoes.
Shield volcanoes – have gently curved slopes with one or more crater
Composite volcanoes – symmetrical tall mountains with a crater top
Scoria cones – cone shape with small crater at top, much rock and debris
Volcanic domes – dome-shape mostly of magma, little ash
Describe a flava flow and a pyroclastic eruption.
Lava flows produce flows of lava and are not very viscus,
pyroclastic eruptions are explosive and throw out much debris including rocks and ash
In what ways should we worry about volcanic eruptions?
Falling objects
Ash in the air
Other gases in the air
Blocked sunlight
Describe the features of a basaltic volcano.
Can produce a jumble of angular blocks, or ropy material
As it moves into water can produce pillows
Describe the features of a composite volcano.
Produce eruption columns
Has viscus lava, but doesn’t move far
Has layers of lava, debris, ash
What is a Caldera?
Large basin shaped volcanic depression
How are mid oceanic ridges associated with volcanoes?
Because they create cracks in the earth’s surface, magma moves into the cracks and the volcanoes process starts very small amounts produced at any one time
