imaging the earth · 2006-08-31 · “imaging the earth” – classically is the work of refining...
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Imaging the Earth
A review by
Paul G. RichardsLamont-Doherty Earth Observatory,
Columbia University, New York 10964, USA
with help from
Tanya Atwater, Roger Bilham, Steve Grand,Rob van der Hilst, Jian Zhang
CTBT: Synergies with Science, 1996-2006 and Beyond; August 31, 2006
Fluid Outer Core
Solid InnerCore
MantleCrust
The major features of planet Earth’s interior,
crust, mantle, fluid core,
have been known for more than 100 years; the
solid inner core was discovered in 1936.
These discoveries were based on observations of
magnetismgravity, Earth’s shape (geodesy)slow movements (tides, precession)fast movements (seismic waves)heat flow
“Imaging the Earth” – classicallyis the work of refining our knowledge ofthe Earth’s internal structure.
“Imaging the Earth” – more generallyconcerns learning about the dynamicprocesses taking place in our planet, thatdetermine its character.
By studying the Earth’s interior today, wecan understand these processes better.
Evidence for the Farallon Plate
shown at three different depths
,
120°W 100°W 80°W 60°W 40°W
40°N
20°N
from P-waves
from S-wavesFARALLON SLAB
2700 km depth
2770 km depth
There is a long list of processes taking place in theEarth’s interior, which we can study today withvarious monitoring technologies.
Scientific study of these processes give insightinto how our planet was formed & how it changes.
Some of these processes influence life on ourplanet — and the location of fossil fuels and ofcommercially valuable minerals.
Two examples:(1) plate convergence and seismic hazard
(biggest earthquakes);(2) inner core rotation.
AlaskaSeismographic
Network
Earthquake inSouth Sandwich
Islands
North-South axis
South Pole
AB
BC
DF
65 ∞ N
60 ∞ N
130∞ W
140∞ W 150∞ W
160∞ W
170 ∞ W
70 ∞ N
ALASKA
∆=150o∆=152o∆=154o
CANADATT01
DAWY
INK
-1 0123-10
123
Constant ∆
IMS
USAEDS
ASN
Eielsonarray
Beaver Creekarray
Burnt Mountainarray
Indian Mountainarray
COL&
COLA
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Sta: IL01
f: 0.6−1.2 Hz
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10 channels at Eielson array (IL01-IL10).
10 channels at Eielson array (IL11-IL19, and IL31).
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1900
1996
“Imaging the Earth” – more generallyconcerns learning about the dynamicprocesses taking place in our planet.
“Imaging the Earth” – more generallyconcerns learning about the dynamicprocesses taking place in our planet.
They made it what it is today.They will shape its future — and ours.
Tomorrow we’ll have a longer discussion:
• how the Earth is imagedat different scales
• how we can model the ground shakingassociated with a large earthquake
• how we can do a better job ofmonitoring earthquakes
and we’ll describe some recentlydiscovered new phenomena.
Final Comments: The need to verify compliance with the ComprehensiveNuclear-Test-Ban Treaty is with us for the long-term.
Sixty years ago, science was called“the endless frontier”
and became widely recognized as the basis for economicprogress and an improved standard of living.
Final Comments: The need to verify compliance with the ComprehensiveNuclear-Test-Ban Treaty is with us for the long-term.
Sixty years ago, science was called“the endless frontier”
and became widely recognized as the basis for economicprogress and an improved standard of living.
There are many ways in which scientific research onplanet Earth can benefit from interactions with the workof CTBT verification – and vice versa.