Transcript Earth interior

r pole
req
Earth has an equatorial bulge and
polar flattening, with equatorial
radius (req) ~21 km greater
than the polar radius (rpole).
The radius (r) of an
equivalent sphere
is 6,371 km.
Equivalent
sphere
Based on satellite mapping,
the earth is now known to be
truly pear-shaped, in that, added
to facts of earth’s equatorial
bulge and polar flattening, the south
pole is ~40 m closer to the earth’s
center than the north pole.
10 m
- 30 m
Whole earth density is twice the average density of surface rocks,
i.e., density must increase with depths inside the earth.
Power Flow
on Earth’s Surface
(trillion Joules per Second)
Solar radiation 173,410
direct reflection
52,000
direct conversion
to heat
81,000
evaporation
40,000
water transport in
oceans and atmosphere
370
photosynthesis
40
Internal heat
flow by conduction
volcanism/hot springs
32.3
32
0.3
Continental crust
Oceanic crust
0 km
100 km
200 km
Inner core
Outer core
Mantle
Earth is a
multi-layered
body.
This is based on the
following evidences:
1. seismic
2. gravity and
3. geomagnetic.
Whole Earth’s
Universe Earth Crust
Hydrogen H 74.500
Helium He 23.840
Oxygen O
Carbon C
Nitrogen N
Silicon
Neon
Magnesium
Iron
Sulphur
Aluminum
Calcium
Nickel
Sodium
Argon
Chromium
Phosphorous
Manganese
Chlorine
Potassium
Other elements
Si
Ne
Mg
Fe
S
Al
Ca
Ni
Na
Ar
Cr
P
Mn
Cl
K
0.8200 29.8
0.3750
0.0910
46.6
15.6
27.7
13.9
33.3
2.1
5.0
1.5
1.8
2.0
0.2
8.1
3.6
0.0830
0.0550
0.0570
0.1040
0.0380
0.0066
0.0074
0.0092
0.0033
0.0030
0.0032
0.0009
0.0011
0.0006
0.0003
The whole earth is richer
in Fe, Mg and Ni, and
poorer in Si, K and Al,
than what is found on the
earth’s surface.
Crust
Mantle
Outer
core
2.8
Inner
core
1.9
2.6
1.5
Whole Earth density = 5.5 gm/cm3
Density of the crust = 2.7 gm/cm3
Crust
Mantle
Columbia Earthquake, February 1999
The damages from January 17,
1994, Northridge earthquake
included
1. collapse of Northridge Meadows
Apartments building that killed 16
people (one third of all the fatalities),
2. destruction of the parking garage at
CSUN, and
3. damage to the overpasses of
Interstate 5 near Castaic Junction
Surface
P
Seismogram
from station A
S
Time since the earthquake occurred
Surface
S
P
Seismogram from station B
Distance from epicenter
Time since the earthquake
occurred (minutes)
P and S waves also yield information on the
earth’s internal structure.
The P-wave “shadow
zone” extends from
103o to 142o from
the hypocenter,
for instance, . . .
P wave
shadow
zone
P wave
shadow
zone
. . . whereas the S-wave “shadow zone” extends beyond 103o from the
hypocenter.
Seismograms at
stations 103o to
142o from the
hypocenter
thus receive
no direct P
or S waves
from that
earthquake.
This occurs
because the
fluid outer core
prevents S waves
traversing through
it and slows the P waves down.
Outer
core
Inner core
Question
Upsala (59o52’N:17o38’E), Sweden, is located 130.57o from
Northridge (34o14’N:118o38’W),
CA. Could we, then, have
Upsala
expected more reliable
estimates of magnitude
and related parameters
Los
Angeles
for January 17, 1994,
Northridge earthquake from Upsala
Seismological
Observatory than from
the U.S. Geological
Survey at Denver, CO?
Earthquake fatalities from AD 1000 to 1988
Fatalities exceeding:
300,000
90,000
10,000
Cities with population of
2 million by the year 2000
Convergent or transform
plate boundaries
Crust
Lithosphere
Asthenosphere
Seismic Wave Velocity
0
4
8 km/s
km
Temperature (°K)
Estimated increase in temperature with depth in the
Earth, as inferred from studies of volcanoes, seismic
wave velocities, laboratory
experiments
and
theory*.
Source:
M.S.T. Bukowinski:
Nature, Sept 30, 1999
pp. 432-433
Dinosaurs had dominated the Mesozoic life but vanished at
the Cretaceous-Tertiary
boundary without leaving
any trace
Meso
-zoic
Paleozoic
Phanerozoic
Cenozoic
Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
Proterozoic
Azoic or Archean
Earth’s evolution
0
Holocene
Pleistocene
2
Pliocene
5
Miocene
24
Oligocene
37
Eocene
Paleocene 58
65
144
208
245
286
360
408
438
505
570
2500
3800
4700
The lead-lead isochron for meteorites
Pb207/Pb204
40
30
20
Pb207
Pb206
= (0.6128+0.014)
204
Pb
Pb204
+ (4.46+0.10)
10
0
0
10
20
30
40
Pb206/Pb204
50
60
Evaporation
60,000 km3
Precipitation
95,000 km3
Evaporation
320,000 km3
Ocean Storage
1,370,000,000 km
Precipitation
285,000 km3
Run-off: 35,000 km3
3
A conceptual look at the hydrological cycle