Geo science

How do earthquakes happen?

A sudden realize of stress through a slip along a fault. The elastic crust snaps back to its unstressed shape which realizes energy rota had been put into straining the crust

How Can a stress occur on a fault?

It occurs along a pre-existing fault in a rock. a strain in the crust gradually builds up in between eathquakes and is realised in seismic waves

what is Seismic waves?

waves of acoustic energy that travel through the Earth or other planetary bodies. They are generated by high-energy sources such as earthquakes, volcanic eruptions, landslides, or man-made explosions. [1, 2]

How to measure waves

Location, Magnitude,Intensity(effects on Humans), Fault plane orientation, Slip direction

Shallow earthquakes

occur on any fault, Many at mid ocean ridges(transform faults), Also seen in continental interiors

Intermediate depth (70-700km)

Convergent boundaries, (deep earth quakes need subduction)

How to figure out where an earthquake happened

1. The difference between arrival times of P-waves and S-waves at reveals the distance between seismometer and earthquakes

2. measure the arrival times of P-waves and S-waves and make at least three seismometer to idefiy the intersection point

How to define an earthquake

1. orientation of Fault

   1. Dip direction:compass direction of steepest decsnt

   2. Dip angle: angle from horizonatk

2. Direction of slip

   1. Dip-slip: slip along dip direction

      1. Normal fault is extension

      2. Thrust or reverse fault is compression

Hazards of seismicity

1. Fault line offsets

2. Violent ground motion.

3. Liqufication

4. Tsunamis

5. Slope Failure

6. Fire roadblocking and disruption of utilities

Critical zone

from the top of the vegetarian canopy to the bottom of the fractured bedrock

Streams

Channels of flowing water

overland flow

surface runoff from the streams watershed

Baseflow

discharge/ seep

Braided rivers

have lots of sediment shred into them, multiple threads transporting materials, lots of dig Chanels, same elev

velocity profiling

measure the water velocity at several points across the stream transect, spinner flow method

benefits of velocity profiling

minimal disturbances, applicable across wide range of stream types

Issues with velocity profiling

very large streams, what if stream shape changes take a long time difficult

ADCP

USES SOUND WAVES TO MEASURE VELOCITY IN A WATER column and stream

Benefits of ADCP

really accurate measurements throughout the whole stream

Issues with ADCP

expensive, depth signal penetration depends on sediment load

measuring streams by discharge

pros: easy to measure water level, can be installed far away from river

cons:clogging of connection to stilling well, flow measurement is only as good as rating curve, clogging of weirs disruption of fish migration

Meandering rivers

move fast. Cut bone erosion: outside of curve moves faster than average

Point bar deposition: inside of curve move slower

Alluvial river deposits

Range of energies, flow rates creates very complex deposits

can be used to make inferences about landscape

can tell how long river is by grain size

Mountain stream

steep deep channel banks make it hard to increase increases inundated area quickly steeper channels slops(easier to move water quicker)

Low Land stream

Large flat flood plain, Easy to increase inducted area once channel is breached. Gentle channels slope hard to drastically increase velocity

hydrograph metrics

longterm, max stage in average year variability in years,

short term: delay between input precipitation, height peak

Flood frequency curve

Likelihood for flood to occur

1.assing each a rank

2. calculate recurrence interval

Dreding

removing vegetation, concrete engineered Chanels

Leveese

raised Chanel bank which contains flow within the canal, needs to be built in the right spot

Diversion change

redirects flow away from the river once reached a creation height

Natural watersheds

more infiltration to groundwater followed vy larger baseflow

longer, later, lower, peaks in discharge

urbanized watersheds

more surface runoff directly to stream, ealier, shorter, higher peaks in streamflow, less base flow to sustain stream between storms, flashy flow

Archimedes principle

buoyancy is an upward force and is exerted by a fluid on an object immersed in a fluid

The buoyant force is equal to the weight of the fluid displaced by the object

The buoyant force allows the object to float or appear to have less weight

Buoyant force

The pressure exerted by the air around the ball that counteracts gravity

convergence

air converges to an area of low pressure at earths source

Rising

The air near the. center of the low pressure makes room for converging air

Divergence

The air at altitude moves out of the way to make room for rising air

If T1>T2

the bail of air moves up, hot air rises in the atmosphere

If T1<T2

The ball of air moves down

cold air sinks in the atmosphere

If T1=T2

The air stays

Reasoning behind Hadly cell circulation

1. some of the energy absorbed by the earths surface is transferred to the lower atmosphere by radiation and thermal conduction

2. Because there is more energy absorbed in the tropics air near the tropics is water rhan air in poles and is less dense and rises

3. This creates low pressure near the surface in the tropics

4. Air at high latitudes at the surface flows to the trops

5. Air aloft at high latitude sinks

6. Air aloft in the tropics diverges to make room for the rising air

Coriolis effect

The apparent curving of the path of long-distance objects, winds, and ocean currents caused by the rotation of the Earth beneath them

Coriolis effect deflecting moving air

Air moving poleward in the northwilll will appear to be deflected to the east or the right

Air moving to the equator in the north will appear to an observer on the earth to be deflected dto. the west

Ferrel circulation

1. the equatorial low where air rises is referred to as the intertropical convergence Zone or ITCZ This is a region of high towering clouds and lots of precipitatipn

2. the subtropical hush is an area of subsidence.Low precipitation

3. the poplar front is and area of convergence where cold air meets warmer air from the ferrel celll where most storms are generated

What is the pH of the ocean and why

8 and HCO3-(from continental weathering)

why. is the ocean more acidic

there is more CO2 with means the ocean aborsobs. CO2 combines with CaCO3 and produces H+ ions

Light facts

Light=elctromagnetic radiation

Light can be described as a traveling wave and as a particle

Flux

Unite area per time

number/(areaxtime)

Black body radiation

Every object with T>0K emits electromagnetic radiation

Temp and color depends on objects temperature

Hotter objects have fast molecular motion, which produces higher frequency, shorter wavelength radiation

Effective temperature

the temperature a planet in thermal equilibrium would be if emitted radiation as a blackbody

greenhouse Gases

a gas whose concentration reduces the ability of longwave radiation to escape earth

Ex: Water vapor, CO2, CH4, O3,

Which greenhouse gas produces the greatest warming effect

H2O

What is the threshold for O2 concentrations

35%, the whole biosphere would burn if above

what proves the atmospheric O2 hasn’t dropped blow 13% for hundreds of Myr

Charcol in sedimentary rocks

What chaceteristic of the earth is not periodic

Magnetic field

what two processes controls the long term carbon cycle

weathering and metamorphism

evidence for snowball earth

banded iron formations, capstone carbonates, drops one, glacial tills at low latitude.

Right lateral strike slip fault

a near-vertical fracture in the Earth's crust where two blocks of land slide past each other horizontally

what earthquake characteristic can be unfired from seismic waves

fault plane orientation, magnitude, slip direction, depth, Lattitude and longitude

Top 3 factors for deterring damage caused by and earthquake

1. the conditions of the soil, sediment, or rock at the location

2. the magnitude of the earthquake

3. the distance of the earthquake epicenter

Most explosive volcanic eruptions driven by

cold, high silica, and gas rich magmas

What do fissure eruptions and shield volcanos have In common

They produce wide flat lying structures, They both erupt balsamic material

Precursors to volcanic eruptions

small to large earthquakes, increases or changes in gasses emitted from a volcano, bulging or deformation of valcano

What promotes melt production

increasing temp and decreasing pressure

Drainage basin

where a stream draws water from

What increases the risk of flooding downstream

dredging Chanels and building levees

Hadleys intialmtheory

Divison of each hemisphere into three circulation of cells, high atmospheric pressure at the equator, and high preciptation rates at mid latitudes