natural disasters review session

Upload: kahwahcheong

Post on 08-Mar-2016

216 views

Category:

Documents


0 download

DESCRIPTION

Natural disasters review

TRANSCRIPT

  • Natural Disasters Review Session Earths magnetic field moves fast, dipole field moves on a measurable time scale, movement is very fast, why? Because liquid iron moves fast enough to account for field movement, but mantle and crust move too slowly. Center of planet is 6000km way down so the interior is very hard to see, and thus mostly inferred through seismology. But chondrites help us know the building blocks and starting composition of the Earth. They also give us information on how much radioactive material (uranium, thorium) is inside our planet, which gives us a good idea about how much heat is coming out of the planet. They also constrain how much water in the interior that would sweat out later to make oceans. Kerogen almost like a hydrocarbon, thick waxy stuff, form in sediments because when photosynthetic stuff falls down, also mixes with mud and sedimentary stuff, decays with bacteria which reduces it (takes out the O) and leaves more of the C and H. This kerogen is 2nd biggest reservoir of C on the planet (after carbonates in limestone etc in the crust). A tiny fraction of kerogen is cooked at right pressure and temperature to make fossil fuels (coal and oil/gas). Big solar flare that sends large flux of charged particles towards the earth, but magnetic field traps them (the Van Allen Belts are like a magnetic bottle); but if the bottle gets over-filled it overflows towards the poles, causing the Auroras and magnetic storms Some hints for the last topics for which there is no pset: 1) Habitable zones relates being in the right place, i.e. to planetary environment, right

    distance from sun, to allow liquid water; 2) And then also being at the right time to have the right elements for life (too early in

    the history of the universe there would be no carbon or oxygen); this doesnt happen until stars started to form that you have elements.

    3) You need at least 5 elements C, H, O, N, P captured in planets and used for life. Didnt exist until about after 4 billion years after universe was made (when big stars were made)

    4) building blocks of life; 5 elements make 4 compounds common to all life Rise of oxygen (important): toxic waste product of photosynthesis, and react with other organic compounds and organisms, oxygen revolution was great for those who could breath oxygen but toxic for anaerobic organisms Endosymbiosis: prokaryotes bonded or one engulfed the other to live symbiotically and make eukaroytes; evidence in our mitochondria inside our cells that are like ancient bacteria Build up of fuels from accumulated photosynthesis (e.g., kerogen reservoir). The table of carbon reservoirs of planet is important; again most bound up in carbonates, rocks (limestones), which connects back to the plate tectonic carbon cycle (DEF will be

  • on final), 60% bound up in these carbonates, 15% in kerogen Carbon capture, if we burn all the fossil fuels, want to capture in biomass, have to triple the existing biomass, i.e,. triple the current number of trees now. Mineral carbon sequestration: reacting CO2 with lava rocks to hide carbon; this reservoir is already so huge that we could burn all fossil fuels and then hide the emitted carbon in carbonate reservoir and have a negligible effect on its mass. But this is easier said than done; the Earth will do this anyway, but extremely slowly; so for us to do it efficiently and have any effect in time we have to speed up the carbonate reaction a lot. Snow line in the formation of the solar system; inside the snow line (about 4AU where 1AU = Earths orbit distance) the Sun heats up early solar system disk and keeps water and other ices from condensing, so they dont condens onto proto-planets and these thus stay dry; outside the snow line its cold enough for volatiles to condense into solids and then snow onto protoplanets leaving more volatile-rich out planets. This explain why there is an inner solar system with terrestrial planets and and outer solar system with volatile rich (gaseous and water-rich) planets. Just before the Sun ignites (starts H fusion) it starts blowing strong solar wind, so material that was not captured by a planetesimal was blown out. Clears the solar system of unused gases and dust.