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Introducción a la Geofísica 2010-01 PARCIAL I Tienen que mandar sus respuestas antes de las 8 pm de HOY. 1) Explain what an Euler Pole (pole of rotation) is in plate tectonics. How is the location sof the pole determined. Why does the specific location of the pole and the rate of rotation , adequately describe plate motion? 2) a) Define, or explain, the terms geoid, geoid anomaly, free-air anomaly, Bouguer anomaly. b) The sea surface is an equipotential, so what is the point of measuring gravity on a ship? c) What is isostacy? What is the primary evidence for it? Why are some areas in North America and Finland not in isostatic equilibrium? What kind of geophysical (gravity) signals do you expect? 3) Briefly describe the mechanical and compositional characteristics of a) Crust b) Mantle c) Asthenosphere d) Lithosphere e) Inner Core f) Outer Core 4) Given a typical oceanic crustal thickness of 6 km and 4 km of water depth, estimate the thickness of the continental crust at sea level and beneath the Tibetean Plateau (5 km high). Assume a constant crustal density of 2900 kg/m3 and mantle density of 3200 kg/m3. 5) The Hawaiian Islands in the pacific show a clear linear trend. What is the standard explanation of this feature? Bathymetry maps show another linear trend of seamounts east of the Hawaiian chain, but the trend is oblique to that the Hawaiian chain. <why do you think this happened? 6) Make a brief summary (with drawn sketches) of the three mayor plate boundaries. 7) Cut the Earth as you would an Apple or an Orange. Sketch the major discontinuities of the Earth. 8) Discuss some of the evidence for continental drift. Why was it so difficult for scientist to accept this theory? Today, what are the major forces we know are acting to allow for plate tectonics? 9) Describe the principle of a gravimeter. What is the difference (how do they work) between absolute measurements and relative measurements? 10) Gravitational acceleration is directed towards the center of mass. With the aid of a sketch showing direction of gravity, explain why gravity is not centrally directed acceleration. 11) Sketch the topography (bathymetry) between the eastern Pacific and the Atlantic (E-W) running through Colombia. Add appropriate names to the different regions. What would be your Bouguer anomaly look like? 12) Explain (in your words) the vertical profiles of rigidity (rheology) in continental lithosphere (see figure below). Why is it different from the oceanic lithosphere case? /#%!. #2534 BRI TT -OHO BRIT TLE LE BRITTLEnDUCTILE TRANSITION TILE DUC BRITTLEnDUCTILE TRANSITION BRITTLEnDUCTILE TRANSITION !34(%./30(%2% TILE DUC $EPTHKM DU CTI $EPTHKM -!.4,% LE -OHO !34(%./30(%2% -!.4,% BCONTINENTALLITHOSPHERE #2534 AOCEANICLITHOSPHERE