EOSC 114 Textbook Notes fragile system+earthquakes.docx

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Earth and Ocean Sciences
EOSC 114
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EOSC 114 MIDTERM 1 Chapter 1: A Global and Canadian Outlook on Natural Disasters - Great Natural Disaster  A natural disaster to so overwhelming that outside assistance is needed to handle the response and recover for the region - Year 2010 has highest peak of fatalities on saw-tooth graph o Many lives lost in Haiti earthquake, heat wave that hit Russia and Czech Republic, and earthquake that hit Chile o A lot more fatalities in Haiti but a lot more damage in Chile - Natural disasters kill more people in poor countries, and recovery is slower because means are limited and insurance is less likely Port-Au-Prince, Haiti Earthquake, Jan.12, 2010 - A past double destruction of earthquakes caused French authorities required buildings be constructed with wood and banned construction relying on concrete - Haiti’s population grew rapidly o Most of its population suffered from poverty, a low literacy rate, and life in poorly constructed, concrete buildings o Lessons of past about building construction were forgotten - Until the earthquake of 2010, Haiti did not have a single seismograph station to monitor earthquake hazard - Today, still a lot of work needs to be done. Maule Earthquake, Chile, Feb. 27, 2010 - Tied for the 6 biggest earthquake - Energy released was equivalent to about 700 Haiti earthquakes - Energy pumped into the ocean created tsunami waves that destroyed coastal towns - Tsunami  long-period sea waves caused y oceanic disturbances, such as fault movements, volcanic eruptions, meteorite impacts, and landslides - Maule earthquake is a “success story because Chile was prepared - A modern building code and an effective preparedness program combined to limit causalities and damage - 2 tsunami warning signs: o 1. Strong ground shaking close to the epicenter  move inland or to higher ground (e.g. in Banda Aceh) o 2. At many distant locations where people may have not have felt shaking, the first wave was preceded by a rapid withdrawal of the sea to low levels that coastal residents would never have seen sign that giant wave would soon strike shore o Coastlines are most vulnerable to tsunamis  west coast of North America Natural Disasters and Natural Hazards - Energy  capacity for performing work - Natural disaster  an extreme event triggered by destructive forces occurring in nature that causes significant disruption to society o Often experienced when society ignores hazardous conditions in the natural environment - Natural hazards  a source of danger to life, property, and the environment, from atmospheric and geological phenomena o Become natural disasters when they intersect with vulnerable communities o E.g. unstable snow and rock, high water levels, etc. - Natural hazards are inevitable, but natural disasters are not - Seismograph  an instrument that records earth motions Frequency, Return Period, and Magnitude - Frequency  the number of events in a given time interval. For waves, it is the number of cycles that pass in a second; frequency= 1/period o Earth experiences on average one great earthquake per year - Return period  the amount of time between similar events; period = 1/frequency o Frequency and return period are the inverse of one another - Magnitude  an assessment of the amount of energy released during an event. o Magnitude scale exist for earthquakes, volcanic eruptions, hurricanes, and tornadoes o E.g. Force of hurricane winds o In seismology, different magnitudes are calculated for the same earthquake when different types of seismic waves are used - Magnitude-frequency concept  concept that the size (intensity and extent) of an event is inversely proportional to its probability - A common misinterpretation is to use the return period to predict exactly when a similar event will happen in the future o Frequency and return period are based on based on statistical probabilities o Are not and should not be used as forecasting measures The Number of Great Natural Disasters Is Increasing With Time - Partly due to the human population more than doubling in size since 1960 - Geological hazards: o Earthquakes  shaking of the Earth by seismic waves radiating away from a disturbance, most commonly a fault movement o Volcanoes  Am opening of the Earth’s surface where magma has poured or blown forth, typically creating hills or mountains - Weather-related hazards: o Storms  A violent weather event featuring strong winds and heavy precipitation (rain, snow, or hail) o Floods  overflowing of a body of water onto normally dry land when discharge exceeds the capacity to contain the flow or when there is an obstruction to flow o Droughts  a prolonged interval of dryness causing damage to plants and animals o Wild-fires  an unplanned fire occurring in a forested area or thick brush - Trend line for geological disasters is almost stable but the line for weather-related disasters increases with time o Indicate that changing weather patterns, including those related to global warming, may increase frequency of certain natural disasters in the future The Number of Human-Made Disasters Has Been Decreasing in Recent Years - Man-made disasters include: urban fires, explosions, aviation and maritime disasters, mining accidents, social unrest, and terrorism - An important success factor is greater awareness about safety, even in the poorest countries. - For the first time, in 2010, # great natural disasters > # mad-made disasters The Number of Natural-Disaster Fatalities is Increasing With Time - In data tables, the numbers present undervalue the number of deaths (because, in many cases, the statistics report only fatalities, not missing people) - Biggest killers worldwide were earthquakes and hurricanes, and the water- related phenomena of severe weather and floods killed more people than volcanoes and landslides - Where humans are concentrated, disasters kill many more people during each high-energy event. Economic Losses From Natural Disasters Are Increasing With Time - Economic causes are greater than just damaged structures: industries and businesses are knocked out of operation, causing losses in productivity and wages for employees left without places to work - 38/40 of the most expensive disasters were due to natural processes. o Dominated by storms (29/40), whereas earthquakes contributed to 5/40 events - Locations of the costliest disasters are different from the worst locations for fatalities o E.g. Hurricane Katrina  most expensive natural disaster but doesn’t appear on the list of deadliest disasters o E.g. Cyclone Bangladesh  deadliest disaster but doesn’t appear on list of most expensive natural disasters - Highest insurance losses occurred in the USA, Europe, and Japan o Developed countries experience larger economic loses and fewer deaths o Their people are better insure, live in safer buildings, and have better warning and evacuation plans The Number Of Natural Disasters In Canada Is Increasing - Canada has a rich diversity in environments o Bounded by 3 oceans o Exposed to many types of natural hazards - Geological disasters remained stable but overall increase in weather-related disasters - Canadian population increased more than 6 fold since 1900’s o Floods may start to be reported as “natural disasters” after subdivisions are build on the river’s flood plain o Increase in # weather-related disasters might also indicate that weather events have become more extreme The Number Of Natural-Disaster Fatalities In Canada Is Decreasing - Majority of disasters are not due to natural causes  several deflect dangers associated with travelling in Canada several decades ago - 3 major disasters: o Influenza, polio, H1N1  Biological disasters are identified as most serious threat o Pan-Canadian heat wave experiences the highest fatalities for a natural disaster in Canada - Why are natural disaster fatalities decreasing? o Improved engineering, long-term prevention, extensive disaster education better warning systems, and rapid intervention In Canada, Economic Losses Are Mostly Due To Weather-Related Disasters - Increasing frequency at which weather-related disasters occur is of serious concern as climate-change scenarios predict that meteorological activity will intensify in the future - Only have statistical history of Canada for the past 105 years o Impact of geological disasters is under-represented because danger has not materialized in historical times - Canada hasn’t experience a great natural disaster in history Population Growth - Vulnerability  exposure to being harmed or damaged o Likelihood that a community will suffer, in terms of fatalities and physical damage - Risk  possibility of being harmed or damaged, often expressed as the product of vulnerability and hazard o Risk = Vulnerability * Hazard o E.g. A sever hazard in a densely populated country will pose a severe risk - Linked to the increase of life and economic loss related to natural disasters - Growing exponentially at about 1.2%/year o More recently the growth has changed to a linear increase of population with time o Expected as the carrying capacity of Earth is approached - Carrying Capacity  maximum population size that can be supported under a given set of environmental conditions o Experts anticipate population to level off at 9/10 billion o First time in past 50 years, rate of increase in human population is decreasing - Asia is vulnerable to great natural disasters because of high population density o Large population live close to active volcanoes of the Pacific Ring of Fire and to earthquake-prone areas Overreliance on Technology - Technological disasters  catastrophic event caused by humans that results in the toxic contamination of the environment o Increasing as the world’s population grows and state economies become increasingly connected and interdependent - In event of natural disaster, failure of a network can cascade in a dangerous domino effect o E.g. Not enough power to support A.C. during heat waves - We are becoming increasingly dependent on technology Poverty and Affluence - Poor countries don’t have enough resources to invest in long-term solutions that would decrease their vulnerability o Don’t have the response infrastructure o E.g. California vs. Iran earthquake  California invested In infrastructure and engineering seismology so drastically smaller consequences o E.g. Hurricane Jean  struck Dominican Republic, Haiti, Bahamas, and Florida. Haiti had highest death toll and Florida the highest insurance bill. - Also vulnerabilities due to affluence lifestyles o E.g. Deaths due do snow avalanches in Canada have been steadily increasing - Education is key to reversing trend How Do Canadians Prepare for Natural Disasters - Public Safety Canada (PSC) is an “all-hazards” organization coordinating the handling of disasters - Mitigation  actions taken to minimize the risk associated with a natural hazard o Winnipeg floodway  saved from flooding > 19 times - Emergency management in Canada follows a “bottom-up” strategy in a hierarchical jurisdictional environment (PSC coordinates) o Individual  municipal  provincial  - Recovery period is a good time to reflect and plan for future Chapter 2: Energy Flows Energy Sources of Natural Hazards - Natural disasters can be classified on the basis of the energy sources that fuel the Earth’s processes: 1. Earth’s internal energy, 2. Solar energy, 3. Gravity, 4. Impact of extraterrestrial bodies - Radioactive elements  unstable elements containing excess subatomic particles that are emitted to achieve smaller, more stable atoms o Interior of earth holds a large store of heat released primarily from outgoing decay of radioactive elements - Earth’s energy flows to the surface o Over short time spans, it is released as eruptions from volcanoes and by earthquakes o Over longer intervals, the flow of energy has produced continents, oceans, and atmosphere o Outward flow of energy causes continents to drift and collide, constructing mountain ranges and elevated plateaus - Continents  lower-density masses of rock - Atmosphere  gaseous envelope around the Earth, composed of mainly nitrogen and oxygen o Average atmospheric pressure at sea level is 101.3 kPa - Gravity  the attractive force between bodies of matter o Greater the mass of the body, the greater its gravitational force o Large mass of the Earth has powerful effects on smaller masses such as ice and rock, causing avalanches and landslides - Hydrologic cycle  solar-powered cycle where water is evaporated from the oceans, dropped on the land as rain and snow, and pulled by gravity back to the oceans as glaciers, streams, and groundwater o ¼ of Sun’s energy that reaches Earth evaporates and lifts water into atmosphere to begin this cycle o Constant pull of gravity helps bring atmospheric moisture down as snow and rain - On short timescales, unequal heating of oceans and atmosphere at Earth’s poles versus equator creates density differences in water and air o Acted on by gravity to create weather, including storms, strong winds, and ocean waves - On long timescales, the Sun and gravity power the agents of erosion that wear away continents and dump broken pieces and dissolved remains in the seas - Erosion  processes that loosen, dissolve, and wear away earth materials. Active agents include gravity, streams, glaciers, winds, and ocean waves - Glaciers  a large mass of ice that flows downslope or outward due to the internal stresses cause by its own weight - Solar energy is also stored in plant tissue to be released later as fire - Asteroids  a small, rocky body that orbits the Sun - Comets  an icy body moving through outer space o Asteroids and comets are an energy source for disasters Origin of the Sun and Planets - Solar System formed by growth of Sun and planets through collisions of matter within a rotating cloud of gas and dust o Solar nebula  spherical cloud of gas, ice, dust, and other solid debris o Gravity acting upon cloud attracted particles, bringing them closer together o As matter drew inward and size of cloud decreased, speed of rotation increased and mass began to flatten into a disk o Greatest accumulation of matter occurred in the center of the disk, building towards today’s Sun o 2 main constituents of the Sun are lightweight elements: Hydrogen and Helium o As central mass grew larger, temperature increase to about 1, 000, 000 degrees Celsius and process of nuclear fusion began (solar radiation) o The inner planets (Mercury, Venus, Earth, Mars) formed so close to the Sun that solar radiation drove away most of their volatile gases and easily evaporated liquids, leaving behind rocky planets o The outward planets (Jupiter, Saturn, Uranus, Neptune) are giant icy bodies of hydrogen, helium, and other frozen material o Jupiter has an enormous mass and created in its area a zone of gravitational perturbations too unstable for formation of large bodies  Chunks of rock remained as discrete entities instead of combining  They still gravitate around Sun in asteroid belt located between Mars and Jupiter, and are main source of meteorites - Nuclear fusion  combining of smaller atoms to make larger atoms with a resultant release of energy - Solar radiation  energy emitted from the Sun mostly in the infrared, visible light, and ultraviolet wavelengths - Meteorites  a stony or iron-rich body from space that passed through the atmosphere and landed on surface of Earth o 2 main classes: stony and iron-rich meteorites - Chondrules  a small, glassy sphere crystallized in space from semi-molten or molten droplets of rock o Most stony meteorites include small rounded grains called Chondrules o Represent the most simple material in Solar System - Work  Distance * Force o Work= Fd=mad - Potential Energy  energy a body processes because of its position o E.g. large rock sitting high on a steep slope o PE=mgh - Kinetic Energy  energy due to motion o KE=1/2(m(v^2)) - Force  mass * acceleration o 1 newton (N)= 1kg m/s^2 - Power  the rate of work (Watts) o Power=work/time - Friction  the resistance to motion of two bodies in contact - Heat  the capacity to raise the temperature of a mass, expressed in joules Age of Earth - Oldest Solar System materials are about 4.57 billion years old o Measured using radioactive isotopes and their decay products collects from Moon rocks and meteorites - Crustal composition  recycled and formed from earlier rocks - Oldest ages obtained from Earth materials are 4.37 billion years - Earth must be younger than 4.57 billion year old materials that collided and clumped together to form the planet o Time it took to build earth is ~ 30 million years - Collision of Earth with Mars-size body that formed our Moon o Suggests that Earth was already a large mass at that time - Unformitarianism  concept that the same laws and processes operating on and within the earth throughout geological time are the same laws and processes operating today o If we can understand how Earth works today, we can use this knowledge to read the rock and fossil record to understand the Earth’s history - Actualism  concept of using the processes operating on Earth today to interpret the past o Rates of earth’s processes can vary o E.g. atmosphere of Earth has changed through time but the physical and chemical laws of atmospheric processes have been the same The Earth’s Early History - Initially, the Earth was a more or less homogeneous mixture of materials: o Bits and pieces of metal-rich particles (similar to iron rich meteorites) o Rocks (similar to stony meteorites) o Ices (of water, carbon dioxide, and other compounds) - The processes of planet formation created LOTS of heat which changed the planet o Heat came from impact heat, gravitational energy, differentiation into layers, and decay of radioactive elements - As internal temperature of Earth rose, it passed melting points of iron at depths below its surface o Iron forms ~1/3 of Earth’s mass and melts at a low temperature o High-density melted iron was pulled by gravity to Earth’s center o As iron moved, it released a huge amount of gravitational energy that converted to heat and probably doubled the earths internal temperature o This would have produced widespread melting to cause low-density materials to rise and form:1. Primitive crust of low-density rock at the surface of the Earth, 2. Large oceans, 3. Dense atmosphere - Planet changed from a homogenous ball into a density-stratified mass with denser material in center and progressively less dense materials outward - Oceans and small continents existed 4.4 billion years ago, life was present as photosynthetic bacteria 3.5 billion years ago, and large continents were present 2.5 billion years ago when process of plate tectonics was initiated The Layered Earth - Earth’s layers can be described either as o (1) Layers based on density due to varying chemical and mineral compositions o (2) Layers with different strengths Density Layers - Earth’s center is a dense, iron-rich core - Core  central zone of the Earth o Mostly made up of iron and nickel and exists as a solid inner zone surrounded by a liquid outer shell. o Outer core is mostly liquid, and convention currents within it are responsible for generating the Earth’s magnetic field - Mantle  the largest zone of the Earth o Layer between core and crust that makes up most of the interior of Earth o The uppermost thickness of the mantle is depleted in light elements and this differs from the zone below - Crust  the outermost layer of the lithosphere, composed of relatively low- density materials. The continental crust has lower density than the oceanic crust o Low-density material is similar to continental crust that, through melting and separation, has risen above the upper-most mantle - Core  mantle  continents  oceans  atmosphere (least dense layer) o Less dense layers rest upon more dense layers o E.g. oceans compromise layered masses of water of differing densities. Very cold and dense  cold  salty  warmer less dense water - Today, continents comprise only 0.1 % of the Earth’s volume Strength Layers - Earth can also be described as a stratified body made of layers of different strength - Temperature and pressure decrease form Earth’s core to surface o Inner core has intense pressure with tightly packed iron atoms into solid crystals o Inner core is enveloped by the outer core where iron exists in liquid form - Mesosphere  the mantle from the base of the asthenosphere to the top of the core o “Stiff plastic” solid - Asthenosphere  the hot low-strength layer of earth below the lithosphere in which isostactic adjustments take place. The rocks here deform readily and flow slowly o “Soft plastic” that surrounds the mesosphere - Materials in these 2 plastic layers flows in large convection cells where certain areas rise and other sink due to spatial variations in Earth’s internal heat - Lithosphere the outer strong and rigid shell of the Earth that lies above the asthenosphere and below the atmosphere and hydrosphere o Most important boundary between the different strength layers is that between the lithosphere and asthenosphere o Earthquakes and volcanoes mark the boundaries of lithospheric plates - Mesosphere  Asthenosphere  Lithosphere  Atmosphere  Hydrosphere - Isotasy  condition of equilibrium wherein the Earth’s crust floats upward or downward as loads are removed or added o Applies a buoyancy principle to the low-density continents and mountain ranges that literally float on the denser mantle below Material Deformation - Stress  force per area; forces include shear, tension, and compression o Shear Stress  a state of stress that causes internal planes within a body to move parallel to each other - Strain  a change in form or size of a body due to external forces - Tension  a state of stress that tends to pull the body apart - Compression  a state of stress that causes a pushing together or contraction - Elastic  behavior of material where stress causes deformation that is recoverable; when stress stops, the material returns to original state o E.g. when you pull on a spring - Ductile behavior of material where stress causes permanent flow or strain o E.g. chewing gum or Silly Putty - Brittle  behavior of material where stress causes abrupt fracture o Stress applied rapidly to material and it abruptly fractures or breaks into pieces - Plastic  the behavior of a material that flows as a fluid (liquid) over time, but is strong (Solid) at a moment in time o If stress applied for a longer time or at higher temperature (as opposed to brittle), some solids yield to pressure by deforming and flowing, by behaving like fluids - Some materials exhibit a variety of behaviors  E.g. Ice - Viscous  the more viscous a substance, the less readily it flows - Increasing temperature causes rock to expand in volume and becomes less dense and more capable of flowing. - Increasing pressure causes rock to decrease in volume and become denser and more rigid. o Most rocks are brittle at low T/p at Earth’s surface. They fracture and create faults o Most become ductile at high T/p found at greater depths. They deform plastically, producing ripples called folds. Internal Sources of Energy - Mainly from ongoing decay of radioactive elements, with smaller contributions from impacts and gravitational compaction - Nuclear Fission  splitting the nucleus of an atom with resultant release of energy o Heat generated flows to the surface constantly via conduction and convention through the mesosphere and asthenosphere, magma in volcanoes, and water in hot springs - Half-life  the length of time needed for half of a radioactive sample to lose its radioactivity via decay o During the first half-life, one-half of the atoms of the original radioactive isotope decay. During the second half-life, one–half of the remaining atoms decay (25% of the original parent atoms) etc. - Beginning of Earth, there were abundant, short-lived radioactive isotopes, which are now extinct. There are also long-lived radioactive isotopes, many of which have now exhausted much of their energy - Early earth had more radioactive isotopes which generated a lot of heat, however, heat conducts very slowly through rock and thus early heat is still flowing to the surface today. o This provides enough energy for tectonic plates to move, volcanoes to erupt, and earthquakes to shake External Sources of Energy - Energy is also supplied externally via gravitational attractions between the Earth, the Moon, and the Sun that add tidal energy to the Earth - Earth’s climate is powered primarily by heat energy emitted from the Sun o Most solar radiation is concentrated in the part of the spectrum visible (light) or nearly visible (infrared and ultraviolet) to humans o Ranges in wavelength from 0.7 (red) to 0.4 (violet) micrometers - The hotter an object the more energy it radiates and increasingly more of the energy is at shorter wavelengths - Solar radiation commonly referred to as “short wavelength” and radiation from Earth is called “long wavelength” - Igneous rocks  rock formed by the solidification of magma - Magma  molten rock material. It solidifies on Earth’s surface as volcanic rock and at depth as plutonic rock Solar Radiation Received by the Earth - Earth receives different amounts of solar energy at different latitudes - 70% Sun’s energy reaching the Earth is involved in activity in Earth’s systems. About 30% is reflected back to space as short-wavelength radiation and is known as albedo - Albedo  the reflectivity of a body; for the Earth, how much solar radiation is reflected back to space - Polar zones: receive less solar energy and are colder thus helping snow and ice form. o Presence of snow and ice raises albedos reflectance off water, soil, and vegetation  makes cold polar climate even colder o Reverse true during warming cycle - Earth’s spin helps set the heat-carrying oceans and atmosphere in motion  Gravity works to even unequal distribution of heat by pulling more on colder, denser air and water masses - Circulation of the rapidly moving atmosphere and slowly flowing oceans is a major determinant of climate and weather - Polar altitudes receive less of Sun’s energy because the incoming solar radiation is spread over a large area and at a low angle o Much is reflected  Heat reflected > heat absorbed - Excess heat from low-latitude equatorial zone is transported to high-latitude polar regions (through water vapor) o This energy often released in severe storms - Average surface temperature of Earth is ~ 15 degrees Celsius but earth is sending heat to space as if its average T is -16 degrees Celsius - Greenhouse effect  buildup of heat beneath substances such as glass, water vapor, and carbon dioxide that allow incoming, short-wavelength solar radiation to pass through but block the return of long-wavelength reradiation o Carbon dioxide and methane absorb and then reradiate much of the long- wavelength energy down to Earth’s surface - On the grand world scale, average annual temperature at and near surface is relatively stable Hydrological Cycle - Driven by solar energy and operates by way of evaporation, precipitation, surface runoff, and subsurface flow - Water rises convectively, due to its lower density, up into the atmosphere, performing initial work of cycle - It is a continuously operating distilling-and-pumping system o Heat from Sun evaporates water, while plants transpire (evaporate from living cells) water into atmosphere o Atmospheric moisture condenses and precipitates as snow and rain o Water then flows under the pull of gravity as glaciers, streams, and groundwater, returning to seas o System is > 4 billion years old and same water runs through the cycle over and over again - Combined percentage of water in atmosphere, rivers, lakes, and shallow subsurface sediments and rocks is only 0.3 % of total  important for life and cycles - Surface and near-surface water helps move chemical elements in solution, sculpts landscape, weathers rocks, and transports deposits sediments  source of freshwater for life Energy Transfer in the Atmosphere - Redistribution of energy could be accomplished by one large convection cell flowing between equator and pole in each hemisphere - Heated equatorial air would rise and flow to poles at upper levels, becoming cooler at poles where it would sink and floor as cold air over surface, becoming progressively warmer on its return to equator o Warm air rises at the equator at the inter-tropical convergence zone (ITCZ) and sinks in the subtropics - Rapid rotation of earth complicates process  it reduces the size of convention cells to increase their # to 3 in each hemisphere o Low, medium, and high latitudes Water- The Most Peculiar Substance on the Earth - Only substance present in vast quantities in solid, liquid, and gaseous states - Highest heat capacity of all solids and liquid, except liquid ammonia - Heat capacity  amount of energy required to raise temperature of a body by one degree - Highest heat conduction of all liquids at normal Earth surface temperatures - Water has highest latent heat of vaporization of all substances o Latent heat  energy absorbed or released during a change of state o Latent heat is carried by water vapor into atmosphere is released when water vapor condenses to liquid rain o A lot of heatnds transported about atmosphere as air masses circulate o Water has 2 highest latent heat of fusion, exceeded only by ammonia - Water is a bipolar molecule o Negative oxygen and positive hydrogen atoms bond together. Readily bonds with ions o Ions  an electrically charged atom or group of atoms - Water has highest dielectric constant of all liquids o Keeps ions apart and prevent bonding, thus maintain a solution  universal constant o Dielectric constant  measure of material’s ability to store electrical charge - Water has the highest surface tension of all liquids o Surface tension  attractive force between molecules at surface of a liquid - Water expands 9% when frozen (abnormal) o Usually substances shrink in volume and become denser o Maximum density of water is at ~ 4 degrees Celsius - Water vapor in atmosphere ranges from 0-4% by volume o Humidity  measure of amount of water vapor in an air mass - Water vapor is the earth’s most abundant greenhouse gas Energy Transfer in the World’s Oceans - Surface circulation of water through ocean basins is mostly driven by winds - Coriolis effect  tendency of moving objects on the surface of the Earth to be deflected due to Earth’s rotation o E.g. flow of direction of surface water - Heat in oceanic current, known as Gulf Stream, adds significant warmth to the winter climate of Atlantic Canada and northwester Europe - Oceans are layered bodies of water with less-dense water layers floating on top of denser water layer - Thermohaline flow  refers to flow of ocean water caused by changes in density - Seawater density increased by: o 1. At high latitudes, where water temperature is lowered o 2. In Arctic and Antarctic, where sea water is made saltier by salts excluded from sea ice o 3. In warm climates, where evaporation leaves remaining seawater even saltier Gravity - Attraction between objects. Humans unable to modify - 2 bodies attract each other with a force directly proportional to product of masses and inversely proportional to square of distance between them o Gravity = (G*mass 1* mass 2)/(distance*distance) - Volume of moon is 1/49 of Earth and mass 1/80 of Earth - Sun’s mass is 323, 000 times greater than Earth. Sun is further from Earth than Moon. - Sun exerts a pull on Earth more than 170 times stronger than Moon - Gravitational system of Earth, Moon, and Sun and their interactions, generates tidal energy o Tidal force caused by differences in gravitational forces on Moon-facing side of Earth compared to back side - Since distance between Sun and Earth is much larger than distance between Moon and Earth, tidal force exerted by Sun on earth is only 45% as strong as pull from Moon - Earth has unique tidal effects because: o 1. 71% of surface is covered by oceans o 2. Has a long period of rotation compared to many other planets o 3. Relatively large Moon nearby - Sun appears overhead once every 24 hours while the Moon takes about 24 hours and 52 minutes o Moon appears to move in sky relative to Sun o These highest tides of the month are called spring tides o In 1 and 3 quarters of moon, Sun and Moon are at right angles to Earth thus producing lowest tides, called neap tides - Tidal bulges can cause frictional braking of Earth’s rotation - As rotation of Earth and Moon slow, they move further apart, days become longer, and years have fewer days - Earth and Moon are separating more every year  lengthening days and shortening days in a year Rock Cycle - Construction and destruction of continents - Mineral  naturally occurring, crystalline substance with a specific elemental composition and a narrow range of physical properties - Linked to the other cycles because depends on tectonic cycle for heat and energy, biochemical cycle for materials, and hydrologic cycle for water - Water plays central role in weathering, erosion, transportation, deposition, and lithification of sediment - Energy flowing up from Earth’s interior melts rock that rises as magma and then cools to crystallizes to form igneous rocks o Plutonic rocks if solidify at depths or volcanic rocks if they cool and harden at surface o These new rocks help create new land - Processes of construction  land-building processes of volcanism, seafloor formation, and mountain building fueled by Earth’s internal energy o E.g. formation of igneous rock - Sediment  fragments of material of either inorganic or organic origin o Gravel, sand, silt, clay (decreasing in diameter)  Mixture of silt and clay forms mud - Processes of destruction  land-destroying processes such as erosion and landsliding fueled by earth’s external energy sources of Sun and gravity o E.g. Sun drives hydrologic cycle, which weathers igneous rocks exposed at/near surface and breaks them down into sediment - Physical weathering breaks rocks into gravel and sand while chemical weathering decomposes rocks into clay - Sediment is eroded, transported mostly by water, and then deposited in topographically low areas, ultimately the ocean - If interior of Earth cooled and flow of internal energy stopped then mountain building and uplift would also stop o Ongoing solar-powered agents of erosion would reduce continents to below sea level in 45 million years thus making an only ocean covered planet - Classified into 3 types: o Igneous  Crystallization of molten rock beneath earths surface o Sedimentary  Rocks near or at surface break down chemically and physically by weathering to form particles known as sediment  Sediment formed by weathering is transported by wind, water, ice, and gravity to depositional sites, such as lakes and oceans  Once wind/water flow slackens, ice melts, or material moving by gravity reaches flat surface, sediment is deposited  During burial, sediment is converted to sedimentary rock by a process called lithification  Lithification  compaction and cementation of sediment during burial o Metamorphic  During burial, sedimentary rocks may be metamorphosed by heat, pressure, and chemically active fluids into metamorphic rocks  Metamorphic rocks may be buried under depths where pressure and temperature conditions cause them to melt, beginning the rock cycle again.  Metamorphic rock can be changed into new metamorphic rock without undergoing weathering or erosion o Sedimentary and metamorphic rocks may be uplifted and weathered before they can continue on to the next stage in the cycle Chapter 3: The Tectonics Revolution Life on the Edge of Tectonic Plates - Uppermost rocky layers move horizontally in process of plate tectonics o Responsible for most earthquakes, volcanic eruptions, and mountains - Plates  piece of lithosphere that moves atop the asthenosphere. There are a dozen large plates and many smaller ones o Earthquakes and volcanic eruptions are mostly distributed along edges of plates  where lithospheric stresses are concentrated - Plate tectonics  description of the movements of plates and the effects caused by plate formation, collision, subduction, and slide past - Tectonic plates  large blocks that form the outer shell of Earth o Earth comprises several internal layers that differ in composition and physical properties - Tectonics  deformation and movement with Earth’s outer layers - Topography  mapping of the shape of the surface of the Earth; the land equivalent of bathymetry - Ridge  lo
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