Hazards Ch 2.

internal structure of earth parts

inner core, outer core, mantle, crust

inner core elemental structure

solid

inner core temperature

high temp

inner core thickness

>1200 km(750mi)

inner core material

90% iron 10% sulfur, oxygen, nickel

outer core distance

>2,200 km (1370 mi)

outer core elemental structure

liquid

outer core density

10.7g/cm

Outer core material

90% iron, 10% sulfur, oxygen, nickle

mantle elemental structure

solid

mantle thickness

~2900 km (1800 mi)

Mantle material

iron and magnesium rich silicate rocks

mantle density

4.5 g/cm

Crust material

rock layer of earth

crust thickness

variable

crust density

3.0 g/cm

moho discontinuity

separation of lighter crustal rock from dense mantle

lithosphere temperature

cool

lithosphere strength

strong and rigid

lithosphere consists of

crust and top of mantle

lithosphere thickness

20-400 km exept below mid ocean ridges

asthenosphere temp

hot

asthenosphere strength

weak and plastic

asthenosphere flow

slow flow

asthenosphere thickness

~600 km

-Pheres of earth from center to space

mesosphere, asthenosphere, lithosphere, atmosphere

continental crust thickness

20-70km average 35km

continential crust age

>7 bil years

continetial crust density

2.7 g/cm

continential crust composition

granitic basement rock

oceanic crust thickness

6-7 km

oceanic crust age

<200 mill years

oceanic crust density

3.0 g/cm

oceanic crust composition

basaltic

seismology

study of earthquakes

where do we learn about earth structure

seismology

earthquakes cause seismic energy T or F

True

Seismic wave movement

some solids, no liquids, reflected, refracted

seismic wave paths infer

earth structure, physical properties, composition

where does magma generate

asthenosphere

lost lithosphere is found where

deep into mantle

lithosphere thickness reflects

age and history

who found the continential drift theory

Alfred Wegner

Continential drift first date

1915

continential drift evidence

fit of africa and south america, fossils found on separated land, glacial reposits on southern continents

why was continential drift abandoned

lack of drive mechanism for movement (tectonic plates not discovered

what brings back continential drift

sea floor spreading

glomar challenger

sonar used to map topography of seafloor

bathymetry

study of sea floor

what does glomar challenger discover

oceanic ridges, deep sea trenches

who proposed sea floor spreading

harry hess 1962

sea floor spreading evidence

new ocean crust at ocean ridges, crust moves laterally from trench to ridge, ocean crust destroyed at oceanic trenches

what renews intrest in continential drift

sea floor spread

palemoagnetism

study of rock remnant magnetism

how can earths magnetic field be represented

a dipole (force line extend from north- south pole

what preserves magnetic field

igneaous rock containing iron that is cooled below curie point

normal polarlity

main force pushing down

reversed polarity

main force pushing up ( upside down)

what shows reversed magnetism

volcanic rock on land

how often are there magnetic reversals

every few hundred thousand years

what is believed to cause magnetic reversal

changes in direction of circulation in outer core

when was magnetic ocean floor mapping invented

1960’s

magnetometers

instruments that measure magnetic properties of rocks

what created Vine and Matthes theory

magnetic anomalies on seafloor 1963

where are ocean floor stripes

parallel to oceanic ridges

what do ocean floor stripes show

areas of normal and reversed magnetic fields

what shows age of ocean rock

magnetic anomalies

how old is sea floor

>200 mil years

what explains stripe pattern

spreading of mid-ocean ridges

Tof F cooling rocks are normally magnetized

True

plate tectonics

large geo processes that deform earths lithosphere by moving over atheosphere

seven major tectonic plates

N. american, s. american, pasific, eurasian, african, indo-austrailian, antartic

how many minor tectonic plates

~12

3 types of plate boundries

divergent, convergent, transform

divergent - plates involved

usually ocean

divergent - dynamics

spreading

what happens during plate spreading

plates move away from each other and molten rock rises to fill gap

divergent - results

ocean ridges form new ocean lithosphere created added to each plate

dovergent - hazards

light/moderate earthquakes

non explosive volcanic eruptions

convergent plates involved

ocean continent, ocean-ocean, continent-continent

convergent Ocean-continent - dynamics

ocean plate sinks beneath continent plate

convergent Ocean-continent - results

volcanic continent arc and deep trench formed

earthquake/volcano activity found here

convergent Ocean-continent - example

andes mountain

formed by nazca and south american plates

divergent - examples

mid- atlantic ridge

from african and north american plates

convergent Ocean-continent - hazards

great earthquakes

explosive volcanoes

tusnamis

flooding

mass wasting

subsidence

convergent ocean-ocean - hazards

great earthquakes

explosive volcanoes

tusnamis

flooding

mass wasting

subsidence

convergent ocean-ocean - dynamics

older denser ocean plate sinks beneath younger

convergent ocean-ocean - results

volcanic islant arc and deep trench formed

earthquakes/volcanos found here

convergent ocean-ocean - example

carribean islands

formed w carribean and south american plates

convergent continent- continent - dynamics

compression bc neither is dense enough to sink

convergent continent- continent - results

large mountain chain formed

common earthquakes

convergent continent- continent - example

himilayan mountains

eurasian and indoaustrailian plates

convergent continent- continent - hazards

major earthquakes

flooding

mass waste

transform- plates involved

ocean-ocean or continent-continent

do the same things

Subduction plate boundries

ocean-ocean, and ocean-continent

collision boundries

continent-continent

transform - dynamics

plates slide past eachother

transform - results

earthquakes and topographic changes

transform - examples

san andreas fault

northamerican and pasific

transform- hazards

stong earthwuakes