Geol Sect 1

Aftershock

smaller earthquakes that occur afterwards in the same place as the mainshock. Depending on the size of the mainshock, aftershocks can continue for weeks, months, and even years

mid-atlantic ridge

splits nearly the entire Atlantic Ocean north to south, is probably the best-known and most-studied example of a divergent-plate boundary

Continental Drift Theory

A: all of the above - Speculated that continental lithosphere moved, but that oceanic lithosphere was stationary - The precursor to plate tectonics

Asthenosphere (Q)

A: all of the above - another name for the upper mantle - source of oceanic basalt - ductile

Convergent plate boundary (Q)

A: all of the above -A collision zone where two or more tectonic plates are colliding together -Associated with subduction

Lithosphere

A: all of the above -composed of the crust and upper mantle -Earth's outermost rocky shell

4 types of plate boundaries

Divergent, convergent, transform, and plate boundary zones.

In a strike slip fault, motion is vertical

False

The Mercalli Intensity Scale is a logarithmic scale meant to quantify the size of an earthquake

False

The Mercalli Intensity Scale is a logarithmic scale meant to quantify then size of an earthquake

False

The Richter scale measures the effects, not the energy (size) of an earthquake

False

The epicenter is below the earth's surface, by the hypocenter

False

Which of the normal, strike-slip, and thrust faults cannot produce tsunami? Why not?

strike-slip faults do not displace water, normal and thrust do displace water

When one plate descends under another plate, sinking into the mantle due to gravity

subduction

Supercontinent

the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass

Asthenosphere

the highly viscous, mechanically weak and ductile region of the upper mantle of the Earth. It lies below the lithosphere, at depths between approximately 80 and 200 km below the surface.

Epicenter

the point on the Earth's surface directly above a hypocenter of an earthquake

Hypocenter (focus)

the point where an earthquake or an underground explosion initiates.

Lithosphere

the rigid, outermost shell of a terrestrial-type planet, or natural satellite, that is defined by its rigid mechanical properties. --On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.

Seismology

the scientific study of earthquakes

Continental Drift

the theory that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed.

Deep ocean trench (oceanic trench)

topographic depressions of the sea floor, relatively narrow in width, but very long. These oceanographic features are the deepest parts of the ocean floor.

List three Natural Disasters associated with subduction zones.

volcanoes, earthquakes and tsunamis

Partial melting

when only a portion of a solid is melted. --an important process in geology with respect to the chemical differentiation of crustal rocks. --at mid-ocean ridges produces oceanic crust --of mantle and oceanic crust at subduction zones creates continental crust. --Partial melts are thought to play an important role in enriching old parts of the continental lithosphere in incompatible elements.

Convergent boundaries

where crust is destroyed as one plate dives under another.

Transform boundaries

where crust is neither produced nor destroyed as the plates slide horizontally past each other.

Divergent boundaries

where new crust is generated as the plates pull away from each other --occur along spreading centers where plates are moving apart and new crust is created by magma pushing up from the mantle (ex. mid-atlantic ridge)

subducting

where plates are moving toward each other, and sometimes one plate sinks(is subducted) under another

A famous supercontinent existing during the Paleozoic and Mesozoic eras

Pangea

A linear zone where the earth's crust and lithosphere are being dragged apart

Rift Valley

Which boundary recycles crust?

Subduction zones are plate boundaries where old oceanic crust is recycled back into the mantle.

tectonic plate

massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere. Plate size can vary greatly

An underwater mountain system that represents a divergent boundary

oceanic ridge

Describe the phenomena of lithospheric plates sliding over the earth's mantle and interacting

plate tectonic theory

A fault represents a fracture in the lithosphere

True

In a strick slip fault the fault plane is vertical

True

In a strike-slip fault plane is vertical

True

Liquefaction is a process that causes a solid to behave as a liquid

True

Mantle plumes (hot spots) explain the formation of volcanos far from plate boundaries

True

The record of earth's magnetism is preserved in rocks

True

Transform plate boundaries show horizontal, rather than vertical motion

True

Seismograph

a device with a base that sets firmly in the ground, and a heavy weight that hangs free. When an earthquake causes the ground to shake, the base of the seismograph shakes too, but the hanging weight does not. Instead the spring or string that it is hanging from absorbs all the movement. The difference in position between the shaking part of the seismograph and the motionless part is what is recorded.

Fault

a fracture in the lithosphere

Volcanic island

a high island or volcanic island is an island of volcanic origin

Divergent plate boundary

a linear feature that exists between two tectonic plates that are moving away from each other. --Divergent boundaries within continents initially produce rifts, which eventually become rift valleys. ***Exists between two tectonic plates that are moving apart from one another

Rift valley

a linear shaped lowland between several highlands or mountain ranges created by the action of a geologic rift or fault. A rift valley is formed on a divergent plate boundary, which is subsequently further deepened by the forces of erosion.

Richter Scale

a logarithmic scale of 1 to 10 used to quantify the size of an earthquake based on energy released

Liquefaction

a process that causes a solid to behave as a liquid

Seafloor spreading

a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.

Plate Tectonics

a scientific theory describing the large-scale motion of seven large plates and the movements of a larger number of smaller plates of the Earth's lithosphere -builds on the concept of continental drift

Oceanic Ridge (Mid-ocean Ridge)

a seafloor mountain system formed by plate tectonics. It typically has a depth of ~ 2,600 meters and rises about two kilometers above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a divergent plate boundary.

Pangea (Pangaea)

a supercontinent that existed during the late Paleozoic and early Mesozoic eras -- assembled from earlier continental units approximately 335 million years ago, and it began to break apart about 175 million years ago. --In contrast to the present Earth and its distribution of continental mass, Pangaea was centred on the Equator and surrounded by the superocean Panthalassa

Continental volcanic arc

a type of volcanic arc occurring as an "arc-shape" topographic high region along a continental margin. The continental arc is formed at an active continental margin where two tectonic plates meet, and where one plate has continental crust and the other oceanic crust along the line of plate convergence, and a subduction zone develops

Convergent plate boundary

an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other causing a process known as subduction.

normal (dip-slip) fault

an inclined fracture where the rock mass above an inclined fault moves down

Plate boundary zones

broad belts in which boundaries are not well defined and the effects of plate interaction are unclear.

High topography that forms above a subduction zone on a continent

continental volcanic arc

What types of plate boundaries have the most volcanoes?

convergent

Modified Mercalli Scale

describes the intensity of an earthquake based on its observed effects

What types of plate boundaries have the most earthquakes?

divergent

Which boundary creates crust?

divergent boundary; two tectonic plates move away from each other and magma (molten rock) rises from the Earth's mantle to the surface, solidifying to create new oceanic crust.

A release of sudden energy in crust us called a(n)

earthquake

A release of sudden energy in the crust is called a(n)

earthquake

a release of sudden energy in the crust is called a(n)

earthquake

A _____ occurs before the main earthquake

foreshock

This is where the earthquake initiates

hypocenter

A linear zone where the earth's crust and lithosphere are being dragged apart

rift valley

Earthquake

shaking when two blocks of the earth suddenly slip past one another

Foreshock

smaller earthquakes that happen in the same place; occurs before the main earthquake

What value on the Richer scale can a megathrust earthquake exceed?

9.0

Strike-slip fault

--the fault plane is vertical, motion is mostly lateral

Layers of Earth, components, and states

1. Atmosphere (gas) 2. Hydrosphere (liquid) 3. Oceanic + Continental crust (low density rock) 4. Lithosphere (Crust and upper-most solid mantle) 5. Mantle: Asthenosphere (weak semi-solid rock) 6. Mantle (strong high-density rock, semi-solid) 7. Outer Core (iron-nickel, Liquid) 8. Inner Core (iron-nickel, Solid)

1. surface wave 2. body waves 3. primary waves 4. secondary waves

1. Travel at the earth's surface 2. travel through the interior 3. can travel through fluids 4. Displace to the ground perpendicularly to the direction of travel

subduction zone

The location where sinking of a plate occurs

Seafloor spreading

The process whereby oceanic crust is created at mid-ocean riders