Download Introducción a la Geofísica

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