Natural Disasters Test 1

Atmosphere

the gas surrounding Earth’s surface

Geosphere

the solid Earth from surface to center

Hydrosphere and cryosphere

the combined system of water on Earth, including oceans, rivers, glaciers, and ice caps.

Cryo =frozen

Biosphere

the global sum of all ecosystems, encompassing all living organisms and their relationships with each other and their environments.

comprise 99% of dry air.

The layer of gases surrounding Earth, primarily composed of nitrogen and oxygen.

Air’s oxygen comes from…

photosynthesis by plants.

Air density and pressure are highest near…

the Earth's surface due to the weight of the overlying air.

Clouds are created when…

air’s water vapor changes state.

Weather

short-term atmospheric conditions

Climate

long-term atmospheric conditions

70% of the geosphere’s surface is

under the oceans as seafloor.

Bathymetry

is the shape of the ocean floor

The ocean floor includes…

flat plains, ridges, and trenches

Continental shelves

fringes of continents under ocean water.

30% of the geosphere

Land

Topography

shape of land surfaces.

liquid water covers

70% of earths surface

97% of surface water is

salty ocean water.

3% of surface water is

fresh, in lakes, rivers, and underground.

Earth’s sea level changes when

ice melts or water evaporates

Distribution of water in the hydro/cryosphere

97.5% oceans

1.9% ice (75% of total fresh water)

0.5% groundwater

0.02% rivers & lakes

0.0001% atmosphere

Most life lives on Earth’s

surface, or in the oceans. (some live above and below earths surface too)

Internal engergy

melts rock which may form a volcano

drives plate movement (Plate movement generates earthquakes)

Earth’s center = as hot as suns surface

sources of Earth’s Internal heat

Leftover heat from the planet’s formation

Heat from the decay of radioactive atoms

external energy

Electromagnetic radiation from the Sun

• Sunlight drives photosynthesis.

gravity

The attractive force exerted by all matter

• Causes land movement, rainfall, and river flow

convection

Less-dense materials rise, more-dense materials sink.

• Seen in atmospheric and ocean circulation, and plate movement

• Often caused by temperature variations and gravity

5 characteristics of minerals

1. Naturally occurring

2. Generally inorganic

3. Homogeneous

4. Crystalline solid

5. Definable composition

3 characteristics of rocks

1. Coherent

2. Naturally occurring

3. An aggregate of minerals

Magma

Molten rock beneath Earth’s surface (when magma solidifies intrusive igneous rocks form)

Lava

molten rock on earth’s surface (when lava solidifies extrusive igneous rocks form)

Physical weathering

Breaks rocks into fragments called clasts

Chemical weathering

changes the chemical composition of rocks

Beds

successive layers of deposited sedement

deposition

Minerals accumulate

Lithification

Clasts are compacted and cemented together

compaction occurs as clasts are squeezed together

Cementation occurs as minerals precipitate out between clasts

Slate

develops when clay minerals become foliated

schist

develops when mica minerals become foliated

compositional banding

may occure when diverse minerals are foliated

Strata

Succession of belts

Earths Crust

15% less dense than the mantle

Oceanic crust

7-10 km thick mostly silica-poor igeneous rock such as basalt and gabbro

continental crust

25-70 km thick mostly silica-rich igneous, sedimentary, and metamorphic rock

Earth’s mantle

consists mostly of silica-poor igneous rock called peridotite, mostly solid rock with specific magma zones

earths core

a sphere of iron alloy at earth’s center

90% iron

5% nickle

5% oxygen, silicon, sulfur, and carbon

Earths outer core

rapidly flowing liquid metal, generates earth’s magnetic field

earth’s inner core

solid metal, 3.5 million times the pressure at Earth’s surface

Lithosphere

rigid and consists of Earth’s crust and upper mantle

Asthenosphere

hot enough to undergo plastic flow

Protolythe

A pre-existing rock

Moho

The seismic-velocity discontinuity that defines the boundary between the Earths crust and mantle

Evidence for Pangaea

1. Mountain belts separated by oceans are aligned

2. matching fossils occur on continents separated by oceans

3. aligned sedimentary rocks follow climate belts across continents

4. aligned, contiguous glacial evidence across continents

Seismic belts include

1. Deep-sea trenches

2. seafloor fracture zones

3. mid-ocean ridges

4. mountain belts

Fracture zones

narrow bands in which vertical cracks bounded by steep cliffs break up the oceanic crust, link the ends of ridge segments to each other. Along the margins of some, but not all, ocean basins are elongate troughs known as deep-sea trenches.

oceanic island

If the top of a peak rises above sea level, it forms an

seamount

whereas if its top lies below sea level

broad continental shelves

along the edges of many continents, where the seafloor depth is less than 0.5 km (0.3 mi).

Active continental margins

boundaries between continental and oceanic lithosphere

are plate boundaries, thus have earthquakes

accretionary prism

As subduction takes place, seafloor sediment, as well as sand and mud that has washed into the trench from nearby land, gets scraped up and incorporated into a wedge-shaped mass, known as an

divergent boundaries

lithospheric plates move away from each other, forms new oceanic lithosphere and hot rock rises producing magma

convergent boundaries

lithospheric plates slide horizontally toward each other, deep sea tenches (oceanic plates slide beneath another plate)

transform boundaries

lithospheric plates slide horizontally past each other

downgoing plate

the plate that sinks (convergent)

Overriding plate

the plate that does not sink (convergent)

Subduction

the process of an oceanic plate slipping beneath an overriding plate

Collision

happens when any two relatively buoyant pieces of crust (such a continent and an island arc) converge at a plate boundary, for such crust cannot be completely subducted

island arc

forms when an ocean plate subducts beneath an ocean plate

continental arc

forms when an ocean plate subducts beneath a continental plate

hot-spot volcanoes

do not form from plate interactions, situated atop mantle plumes, move off mantle plumes as plates move

mantle plumes

columns of especially hot asthenosphere, fixed

separation of plates

occurs often in oceans, seafloor spreading, creates mid-ocean ridges

geologic stress

force applied over an area

1. compression

2. tension

3. shear

caused deformation

shear

adjacent rock moves parallel to a plate boundary

eons

divided into eras, periods, and epochs

Ga: billions of years

Ma: millions of years

Ka: thousands of years

Seismicity

earthquake activity

seismic waves

vibrations generated by earthquakes

seismology

the scientific study of earthquakes

seismologists

scientists who study earthquakes

Joints

cracks in rock, but without shear along the crack, planes of weakness

faults

cracks in rock where shearing occurs, (displacement = amount of movement across the fault)

fractures in rock

develop when crust experiences deformation

movement, called slip, occurs on either side of the fracture

Hanging wall

the rock above the fault plane

footwall

the rock below the fault plane

normal faults

hanging wall moves down fault plane, relative o footwall

occur due to tension stress along divergent plate boundaries

reverse faults

hanging wall moves up fault plane, relative to footwall

occur due to compression along a convergent plate boundaries

Strike-Slip Faults

movement occurs parallel to the strike line (strike line = horizontal line of a fault plane)

no vertical motion on either side

focus/hypocenter of earthquake

the location inside earth where seismic waves begin

epicenter of earthquakes

the point on earth’s surface directly above the focus

foreshock

a cluster of small earthquakes preceding a mainshock

mainshock

the largest earthquake of a sequence

aftershocks

a cluster of small earthquakes following a mainshock

bodywaves

travel through earth’s interior

P-waves=primary=compression motion parallel to the wave

S-waves=secondary-shearing motion perpendicular to the wave

Surface waves

travel on earth’s surface, slower than body waves

L-waves= love waves = horizontal shearing motion, like a snake

R-waves= Rayleigh waves= vertical motion of rolling undulations

Wavelength

P-waves= the distance between successive dilations or contractions

Other waves= the distance between successive crests or troughs

Wave height

the distance between a crest’s top and a trough’s bottom

Amplitude

half the wave height

Attenuation

waves weaken with increasing distance from the focus

some rocks absorb energy

as energy spreads out it covers more area

amplification

waves slow down as they enter weaker rock

slowing velocity causes wavelength to shrink but amplitude to grow

seismographs

a device that measures and records ground motion

seismograms

the record of an an earthquake produced by a seismograph

horizantal axis recors time

vertical axis record amplitude of seismic waves

arrival time on seismograms

the instant when a seismic wave appears

p waves arrive first (fastest)

s waves arrive second (slower)