EOSC 114 Unit 1 Fragile System

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Earth and Ocean Sciences
EOSC 114
Leah May Ver

Unit 1: A Fragile System  Explain what density is & how it relates to stratification. o Density = mass/volume; how much mass fits into a space. Unit: kg/m 3 o Stratification = less-dense materials float on top of denser materials  This is found in the atmosphere, the ocean, the earth, etc.  Explain why disaster scales are based on the Order-of-Magnitude concept, and interpret graphs with logarithmic scales. o Without using a log scale, sometimes a graph will be too large. o “Orders of magnitude” are powers of 10 – a logarithmic graph steps by powers of 10  Converting an exponential curve into a logarithmic graph will give a linear graph. o Many disaster scales use powers of 10: Richter, Fujita, Torino, Beaufort, etc.  Relate natural-disaster risk & intensity to frequency, return period, and consequences (costs). o Risk = probability severity * cost of damage ($ + human lives) o Intensity is inversely proportional to frequency. o Return period = average number of years between disaster events of the same magnitude  RP (M) = time span of data / # of cases of magnitude M.  Explain how some recent disasters were associated with concentration or dilution of energy. o Time scales for energy to build up and release Concentration of energy Dilution of energy  Earthquakes: years -> minutes  Tsunami: minutes -> hours  Volcanoes: decades -> days  Floods: hours -> days  Hurricanes: months -> days  Storms: hours -> minutes  Rogue waves: hours -> seconds  Get the disaster info you need from reliable sources.  Compare tectonic, rock, hydrologic, and biogeochemical cycles.  Tectonic Cycle o Involves the creation -> movement -> destruction of plates o One cycle can last more than 200 million years! o Types of plate boundaries  Divergent: two plates move away  Forms: large, underwater mid-ocean ridges  Rifts formed through seafloor spreading  Convergent: two plates collide  Subduction zone: one plate moves beneath another (usually ocean and continental)  At 100-120 km, melts and releases H2O and CO2 -> hot enough to cause lower crust to melt -> magma moves up -> reaches surface -> erupts  Transform boundary  Movement along a transform fault – most are beneath oceans but some are on continents  Rock Cycle o Rock: aggregate of one or more minerals. Mineral: naturally occurring crystalline substance w/ specific elemental composition o Rock Cycle: recycling of three major groups of rock  Crystallization of molten rock -> igneous rock beneath/on Earth’s Surface  Weathering -> sediment  Sediment is transported by wind/water/ice to depositional sites  Buried -> lithification -> sedimentary rock  Chemically active fluids + heat + pressure cause metamorphic rock to be formed  Eventually, temp high enough -> melt -> restart   Water Cycle o Cycling of water from oceans -> atmosphere -> continents -> back again o Driven by solar energy o Residence time: estimated avg time a drop of water spends in any part of the cycle  Only a tiny fraction of earth’s water is active at a certain time – often stored  Only ~.3% of all water important for life -> groundwater  Biogeochemical cycles o Cycling of an element/elements through atmosphere/lithosphere/hydrosphere/biosphere  Related to the other cycles  Tectonic provides water + gas, heat + energy. Rock and hydrological transfer and store.  Elements and chemicals are transferred via storage compartments/reservoirs  When a biogeochem cycle is understood, the rate of transfer (flux) among all components is known  List the 1st and 2nd most common elements in the earth, ocean, and atmosphere. Elements Earth Crust Ocean Atmosphere st 1
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