Plate Tectonics and Earthquakes

Anomalies

changes on ocean floor

Earthquakes are....

greatest natural threat to humans

How was WWII relevant to plate tectonics?

submarines had sonar sonar inadvertently maps the ocean floor

What season did they decide to work on these things?

summer, better weather and no winter storms

What actually moves are __________/________________ plates.

tectonic/lithospheric

What are the three types of seismic waves?

-primary waves (P) -secondary waves (S) -surface or long waves (L)

What were the 4 other ideas?

-rafting- animals hitched rides across bodies of water -island stepping stones-islands popped up and animals jumped to it -isthmian links-"land bridges" - time of low sea level - ice age -continental drift- very unproven and a cold topic

Depths (how much it occurs)

-shallow (a lot) -intermediate (middle) -deep (not much) ----the deeper you go, the less solid the Earth is

What can earthquakes be caused by?

-slippage long faults - big ones -volcanic erruptions -nuclear explosions

Elastic Rebound

-stresses build up as plates slide past each other -eventually frictional resistance holding the rocks together is overcome ---rocks ruptures, rocks on each plate snap back to their original state

Other explanations included __________________________________.

island hopping, rafting, and land bridges

3. landslides

liquefaction and slumping of saturated layers

When basalt hardens these minerals act like ____________________________.

little bar magnets

Epicenter

location of an earthquake on Earth's surface -directly above the focus

What are the certain minerals that are magnetic?

magnetite (Fe3O4) hematite (Fe2O3)

Certain minerals such as __________&________ are magnetic.

magnetite and hematite

The use of sonar inadvertently ____________________________.

maps the ocean floor

Modern animals like the ___________ were used to prove his theory.

marsoupials

Where does the most damage occur?

most damage occurs within 15-30 miles of the epicenter

Which factors that cause damage can be different because we have human control over them

proximity to humans/buildings design of buildings

What is seafloor spreading?

pushes continents apart

Foreshocks

small earthquakes that precede larger ones

Aftershocks

smaller earthquakes that follow the main earthquake as rocks adjust to new stress fields

Paleomagnetism

study of ancient magnetism in basalts certain minerals are magnetic basalt contains minerals and acquire magnetism when magma hardens

Another name for a place where plates collide is a _____________ zone.

subduction

cynognathus

triassic land reptile

lystosaurus

triassic land reptile

Is intensity similar?

very subjective differs from areas

What is an earthquake?

vibration in the Earth caused by a rapid release of energy

The plates move about as fast as _________________________.

your toenails grow 2-11 cm/year

Earthquake predictions: short-range predictions

(few hours to days) monitoring "precusors" measuring strain in rock, monitoring animal behavior, watching ground water levels

Long-range prediction

(years) statistical estimates of ground motion over time -identify "seismic gaps" - areas that have not had recent quakes -not certain how reliable these methods are

In _________, German meteorologist ___________________ proposed his theory.

1. 1915 2. Alfred Wegener

Mountain ranges like the ________________ here on the East coast and in _________________, _________________________, ______________________ matched.

1. Appalachians 2. England 3. Scotland 4. Ireland

The discovery of the ________________________________ led to the idea of sea-floor ______________.

1. Mid-Atlantic Ridge 2. spreading

Proof

1. The basalt making up the ocean floor gets progressively older moving away from the ridge center. 2. The fossils in the sediment on the ocean floor gets progressively older moving away from the ridge center. 3. The sediment on the ocean floor gets progressively thicker moving away from the ridge center. 4. Given a certain distance from the ridge center in both directions, the basalt making up the ocean floor is the same age. 5. Paleomagnetism

Plate tectonics is the theory that ___________ and _________ move around the earth on large ____________.

1. continents 2. oceans 3. plates

The three boundaries are __________, ___________, and _______________.

1. convergent 2. divergent 3. transform

Three different types of plate boundaries?

1. convergent 2. divergent 3. transform

Convergent boundaries are plates __________ and divergent boundaries are where plates are ___________.

1. destroyed 2. created

Dinosaurs, who are not migratory are found ___________, while migratory groups like _____________ are not.

1. every where 2. mammals

What are two important things at MAR?

1. it lies between the continents, almost equidistant from each shoreline 2. configuration of it mimics coastlines

Factors that cause the damage

1. magnitude of quake 2. duration of vibration 3. stability of substrate upon which buildings occur -loose fill or bedrock 4. proximity to humans/buildings 5. design of buildings

The three types of subduction zones are ________________________, ______________________, __________________________.

1. ocean vs ocean 2. continent vs continent 3. continent vs ocean

Proposed by both ____________ and ______________.

1. scientists 2. nonscientists

What was Wegener's proof?

1. similarity of coastlines 2. mountain ranges on seperate coastlines 3. fossils of similar animals on seperate coasts -dino fossils are found on all continents and mammal fossils aren't 4. paleoclimates 5. modern animals 6. glaciation

What is the damage caused by?

1. the shake of the quake 2. tsunami - seismic sea wave (tidal waves is what it used to be called) 3. landslides 4. fire

Lithospheric Plates

50-75 miles thick, includes crust and upper mantle

What was the public's reaction to Wegener?

50/50 split of how they felt about it couldn't prove how continents moved

In the 19____'s, scientists flocked to this area.

60

Earthquake belts

95% of earthquakes

Who were the two people who talked about seafloor spreading?

Harry Hess - Princeton geologist Robert Dietz - US Coast and Geodetic Survey

Where did the scientists look on the Ridge and why?

Headed to the North Atlantic because that is where the ridge is closest to the surface of the water

Largest magnitude earthquake

Lisbon 1755 (9.5)

Glaciation

Paleozoic glaciation has no pattern with the continents in their present configuration, however, if the continents are placed together then glacial evidence (moraines, striations, drift) all match up

The giant landmass was called __________.

Pangaea

The area around the Pacific Ocean is called the ________________.

Ring of Fire

In the 1960's what occurred?

Scientists flocked to Mid-Atlantic Ridge a deep sea drilling team (Fredrick Vine and Drummond Matthews) headed there to prove sea floor spreading

Modern Animals

The strange evolutionary pattern of the marsupials on Australia indicate that the continent has been isolated from other land masses after a certain point in the evolution of mammals

Mercalli Intensity Scale (1902)

US & Canada -drawbacks = difficult to apply globally -not related solely to earthquake size

The onset of _____________ brought the theory back into the spotlight.

WWII

Magnitude

amount of energy released by seismograms

Divergent

area where plates are forced apart volcanic mountains are produced

Transform

area where plates slide past eachother volcanoes and large earthquakes are common ex. San Andreas Fault

What is Pangaea?

came together and seperated millions of years ago and continents continually moving across the ocean floor

The discovery of __________ on Antarctica was used.

coal

Divergent Plate Boundaries

continental rifts magma rises beneath a continent continent splits apart creates "rift valleys" that are filled with volcanic material and sediments

He could not prove his theory because he __________________________________________.

couldn't prove how they moved (no mechanism)

Intensity

degree of Earth shaking based on amount of damage

Primary (P) waves

fastest waves, compressional (push-pull) motion moves through solids, liquids, and gases

How do earthquakes occur?

focus - the source (location) of an earthquake -energy radiates out from the focus

glossopteris

fossil fern

mesosaurus

freshwater reptile

2. tsunami

generated by submarine landslide or displacement along a submarine fault -more at 300-600 mph -attain heights of 100 ft as they approach land

The ___________ were the main detractors to Wegner.

geophysicists

The sediment on the ocean floor ____________________________________.

gets thicker moving away from the ridge

When is the ocean floor the same age and has the same magnetic orientation?

given a certain distance from ridge center in both directions this occurs

Paleozoic ____________ has no pattern in the world today, but line up the continents and a pattern emerges.

glaciation

Three different types of fossils?

glossopteris, cynognathus, mesosaurus, lystosaurus

Travel-time graphs

graphs of the arrival time of P & S waves that are used to calculate the distance to an earthquake -difference between arrival time of P & S waves is proportional to distance ---need data from at least 3 different seismographs

What was the difference between Wegener vs others?

he actually answered the critics and they kinda shit on him for it because he couldn't explain how the continents shifted

Given a certain distance from ______________________________________.

in both directions, the ocean floor is the same age.

Seismograph

instruments that record seismic waves -contains a free-hanging pendulum -when earth shakes pendulum remains stationary but rest of device shakes

Is there a reliable method of earthquake prediction (short term) ?

no reliable method

Magnitude (2)

objective - a number based on amplitude of largest seismic waves uses logarithmic scaled

Paleoclimates

old climates coal deposits in Antarctica indicate a warm, swampy environment

The basalt on the ocean floor _______________________________.

older as you move away from the ridge

The fossils in the sediment _____________________________.

older as you move away from the ridge

Seismograms

records of seismic activity generated by seismographs P 1st, S 2nd, and L 3rd

The discovery of magnetic __________________ on the ocean floor led to irrefutable proof of moving continents.

reversals/anomalies

4. fire

ruptured gas lines and electric lines -fire-fighting hindered by ruptured water lines and congested roads

What is the Mid-Atlantic Ridge?

series of volcanic mountains 40,000 miles long 1,500 miles wide 2 miles high

Earthquake depth

shallow <45 miles, intermediate = 70-185 miles deep, >185 miles

One of the many elements he used for proof was the ____________ of coastlines.

similarity

Secondary (S) waves

slower, oscillate (shaking motion), moves through solids only

Surface or Long (L) waves

slowest, travels along Earth's surface, does the most damage

Therefore given a certain distance from ______________________________________.

the center of the ridge in both directions, the ocean floor is the same age and magnetic orientation

Seismology

the study of earthquakes started 2,000 years ago in China US after 1906 San Fran quake -vase w/ dragons and marbles to define which direction

The type of boundary in California is a _____________ boundary.

transform