Hanya ingin koreksi sedikit, sebab cukup banyak yg melakukan kesalahan ini.
Presentasi beda dg persentasi atau prosentase. Yg dimaksud di bawah
tentunya adalah persentasi (atau prosentase) yg dilambangkan '%'.
Maryanto
<[EMAIL PROTECTED] To: "'[EMAIL PROTECTED]'" <[EMAIL
PROTECTED]>
.com> cc: bambang_dwiyanto <[EMAIL PROTECTED]>,
Herman
Moechtar <[EMAIL PROTECTED]>, Ukat Sukanta
at CPI
09/30/03 11:02 <[EMAIL PROTECTED]>, "'Sardjono'" <[EMAIL
PROTECTED]>, "Indra
AM Budiman (E-mail 2)" <[EMAIL PROTECTED]>
Please respond Subject: RE: FW: [iagi-net-l] Re:
korelasi geodinamik
to iagi-net
Wah mantab dapat info dari filosof-filosof besar: Prof. Koesoema, Pak ade,
Pak Awang. Saya senang dengan susunan dari beliau ketiga. Saya tambahkan
data USGS updated 5-5-1999 dibawah (smoga tak kepanjangan). Gambar ada
diinternetnya. Susunan ini relatif mirip dengan susunan diatas dan sedikit
berbeda. Kok 7 lapis batuan bumi ya gambar disana ? Dari data Pak Ade, dan
dengan asumsi 70 % laut, 30 % darat, lalu kami hitung presentasi ketebalan,
dan menjadi berturut-turut :
Nama lapisan, Avrg. batas bawah lapisan dari surface(km), Avg. tebal (km),
Presentasi ketebalan terhadap jejari Bumi (%), elatisistas :
1.Crust ( 13, 13, 0.2, solid)
2.Listhoferic mantle ( 116, 103, 1.6, solid)
3.Asthenospher ( 250, 134, 2.1, ductile)
4."Tansition Zone" ( 400, 150, 2.4, solid)
5.Lower Mantel (2900, 2500, 39.2, solid)
6.Outer core (5100, 2200, 34.5, liquid)
7.Inner core (6378, 1278, 20.0, solid)
Lithosfere adalah Crust dan Listhoferic mantel (2 % dari jejari bumi)
Mantel : Lower mantel, transition zone, asthenosfer, listhoferic mantel.
Core : inner core, dan outer core.
Bagaimana dengan susunan baru itu ? Tentu banyak variasi susunan lain.
Salam,
Maryanto.
http://geology.about.com/gi/dynamic/offsite.htm?site=http%3A%2F%2Fpubs.usgs
.
gov%2Fpublications%2Ftext%2Finside.html
Inside the Earth
The size of the Earth -- about 12,750 kilometers (km) in diameter-was known
by the ancient Greeks, but it was not until the turn of the 20th century
that scientists determined that our planet is made up of three main layers:
crust, mantle, and core. This layered structure can be compared to that of
a
boiled egg. The crust, the outermost layer, is rigid and very thin compared
with the other two. Beneath the oceans, the crust varies little in
thickness, generally extending only to about 5 km. The thickness of the
crust beneath continents is much more variable but averages about 30 km;
under large mountain ranges, such as the Alps or the Sierra Nevada,
however,
the base of the crust can be as deep as 100 km. Like the shell of an egg,
the Earth's crust is brittle and can break.
Cutaway views showing the internal structure of the Earth. Below: This view
drawn to scale demonstrates that the Earth's crust literally is only skin
deep. Below right: A view not drawn to scale to show the Earth's three main
layers (crust, mantle, and core) in more detail (see text).
Below the crust is the mantle, a dense, hot layer of semi-solid rock
approximately 2,900 km thick. The mantle, which contains more iron,
magnesium, and calcium than the crust, is hotter and denser because
temperature and pressure inside the Earth increase with depth. As a
comparison, the mantle might be thought of as the white of a boiled egg. At
the center of the Earth lies the core, which is nearly twice as dense as
the
mantle because its composition is metallic (iron-nickel alloy) rather than
stony. Unlike the yolk of an egg, however, the Earth's core is actually
made
up of two distinct parts: a 2,200 km-thick liquid outer core and a 1,250
km-thick solid inner core. As the Earth rotates, the liquid outer core
spins, creating the Earth's magnetic field.
Not surprisingly, the Earth's internal structure influences plate
tectonics.
The upper part of the mantle is cooler and more rigid than the deep mantle;
in many ways, it behaves like the overlying crust. Together they form a
rigid layer of rock called the lithosphere (from lithos, Greek for stone).
The lithosphere tends to be thinnest under the oceans and in volcanically
active continental areas, such as the Western United States. Averaging at
least 80 km in thickness over much of the Earth, the lithosphere has been
broken up into the moving plates that contain the world's continents and
oceans. Scientists believe that below the lithosphere is a relatively
narrow, mobile zone in the mantle called the asthenosphere (from asthenes,
Greek for weak). This zone is composed of hot, semi-solid material, which
can soften and flow after being subjected to high temperature and pressure
over geologic time. The rigid lithosphere is thought to "float" or move
about on the slowly flowing asthenosphere.
http://geology.about.com/library/weekly/aa081599a.htm
Getting to the Core
The Century in Review: It took years of ingenious work
A hundred years ago, science barely knew that the Earth even has a core.
Today, we are tantalized by the details we know about the core and its
connections with the rest of the planet. In fact, I think it's the start of
a golden age of core studies.
We knew by the 1890s, from the way the Earth rocks in response to the
gravity of the Sun and Moon, that the planet has a heavy core, of the
density of iron. In 1906 an early seismologist, Richard Dixon Oldham,
determined that earthquake waves move through the central part of the Earth
much slower than through the mantle around it. This is because the center
is
liquid. He discovered the core.
Earth cross section. U.S. Geological Survey image.
In 1936 Inge Lehmann documented that an inner core reflects some seismic
waves from deep inside the core. Gradually it became clear that the core
consists of a thick shell of liquid iron - the outer core - and a small
solid iron sphere at the Earth's very center - the inner core.
Lately there are hints of an even smaller inner-inner core. In October
2002,
Miaki Ishii and Adam Dziewonski of Harvard University published evidence of
a tiny "innermost inner core" some 600 kilometers across. (They've been
presenting this work since spring of 2002 but could not get it published
until the relatively permissive National Academy of Sciences Proceedings
accepted it.) Not much can be made of this until others confirm the work.
Whatever we learned has only raised more questions. For instance, the
liquid
iron is obviously the source of Earth's geomagnetic field-the geodynamo-but
how does it work? Why does the geodynamo turn over, switching magnetic
north
and south, at random intervals over geologic time? And what happens at the
top of the core, where molten metal meets the silicate rock of the mantle?
Some of these questions began to be answered during the 1990s.
In the 20th century, our main tool for deep-Earth research has been the
study of earthquake waves. Naturally, the passage of time brings us more
and
better seismic data to play with. Also, the 1994 Bolivia quake and other
large deep events gave the whole Earth a good shaking. The ringing "normal
modes" that followed, making the planet pulsate with the sort of motions
you
see in a large soap bubble, were well recorded with modern seismographs.
These are very useful for examining large-scale deep structure.
The biggest problem with seismic studies is nonuniqueness, a great word for
your next Scrabble game. That is, with any given piece of evidence there is
more than one way to interpret it. A seismic wave that penetrates the core
also travels through the crust at least once and through the mantle at
least
twice, so when a pattern shows up in a seismogram, pinning down what it
signifies is very hard. It takes a large amount of cross-checking different
pieces of data.
The problem of nonuniqueness faded some when computers and software became
powerful enough to make interesting simulations of the deep Earth with
realistic numbers. And it also made a big difference when we could
reproduce
the heat and pressure of the Earth's center in the laboratory, using the
diamond-anvil cell. In combination, these approaches have let us peer
through the different layers of the Earth until at last we can contemplate
the core.
-----Original Message-----
From: Ade Kadarusman [mailto:[EMAIL PROTECTED]
Sent: Monday, September 29, 2003 9:37 Pagi
To: [EMAIL PROTECTED]
Subject: Re: FW: [iagi-net-l] Re: korelasi geodinamik
Pak Koesoema,
Sebenarnya pembagian lapisan bumi diawali oleh penemuan
crust-mantle boundary (Moho) oleh Mohorovicic 1909 dan Guternberg
(1913) & Lehman (1936) untuk outer/inner core menggunakan gelombang seismic
(P and S wave). Ini mungkin yang dimaksud oleh Pak Koesoema Rheology-nya ?,
pembagian lithosphere, asthesnophere, mesophere hanya berlaku unutk crust
dan
upper mantle, tidak untuk Core-nya.
Kemudian Ringwood (1975, 1979) menerjemahkan
komposisi Bumi dari gel. seismik tersebut dalam bentuk susunan kimia
atau mineralogi (yang dikenal sekarang sbg pyrolite model untuk mantle, dan
Fe-Ni model untuk core).
Dari monograph Ringwood inilah kita mengacu lapisan bumi yang sekarang kita
kenal, crust, upper mantle, lower mantle, outer-inner core.
Dan pada perkembangannya digunakan pula istilah lithosphere dan
asthenosphere
untuk membagi lagi lapisan bagian atasnya (crust dan upper mantle).
Kemudian lapisan bumi tsb sekarang disempurnakan oleh Dzienwonksi dan
Anderson (1981) dalam suatu klasik paper "Spherical Earth model PREM (
Preliminary Reference Earth Model) dari data seismik velocities Vp, Vs,
dan density.
Itu mungkin tambahan dari komentar Pak Koesoema.
Salam
Ade Kadarusman
From: Awang Satyana [mailto:[EMAIL PROTECTED]
Sent: Friday, September 26, 2003 3:32 Sore
To: [EMAIL PROTECTED]
Subject: Re: FW: [iagi-net-l] Re: korelasi geodinamik
>>Secara rheologi Crust dan Upper Mantle termasuk Lithosphere, sedangkan
Lower
>>Mantle termasuk Asthenosphere
Lower Mantle termasuk Asthenosphere ? Bukannya termasuk ke Mesosphere Pak ?
Upper Mantle dari depth 35-670 km (670 km diambil sebagai batas hiposentrum
gempa terdalam), Lower Mantle dari 670-2885 km. Sedangkan batas
astenosphere
terdalam adalah 220 km, sehingga Lower Mantle bukan astenosphere dari segi
mekanika/rheologi.
Kemudian, klasifikasi lain menyebutkan bahwa secara rheologi Bumi terbagi
jadi empat lapisan : lithosphere, asthenosphere, mesosphere, dan
siderosphere. Siderosphere secara mineralogi/kimiawi adalah outer dan inner
core.
Mengenai nama, sebenarnya sebutan lithosphere tidak cocok dari segi
rheologi. Lithosphere tidak mengesankan suatu sifat rheologi tetapi lebih
ke
penyusun (mineralogi); lithos = batuan. Asthenosphere cocok, sebab asthenos
= without strength. Kalau mau, lithosphere mestinya sclerosphere = hard.
Salam,
Awang
Prof. Koesoemadinata:
> Sebetulnya ada 2 cara menetapkan susunan bumi:
> 1. Secara rheologi dan 2. Secara susuman mineralogi/kimiawi:
>
> 1. Secara rheology bumi tersusun dari a. Lithosphere, b Asthenosphere dan
c.
> Mesophere
>
> 2. Secara susunan mineralogi/kimiawi: a. Kerak (Crust) yang dibagi atas
> Continental Crust dan Oceanic Crust, b. Mantle (dibagi lagi jadi Upper
> Mantle atau Mantle Lid, dan Lower Mantle), c. Core (Outer core, Inner
> Core).
>
> Secara rheologi Crust dan Upper Mantle termasuk Lithosphere, sedangkan
Lower
> Mantle termasuk Asthenosphere
> Yang disebut "tectonic plate" adalah sebetulnya Lithosphere (yang secara
> umum bersifat rigid), yang bergerak di atas Asthenosphere (yang bersifat
> ductile). Yang disebut continental plate adalah plate yang bagian atasnya
> adalah continental crust, sedangkan oceanic plate adalah plate yang
bagian
> atasnya adalah oceanic crust.
> Kekeliruan dari teori Continental Drift dari Wegener adalah seolah-olah
> continental crust bergerak di atas oceanic crust
> Kekeliruan umum adalah mencampur-baurkan istilah2 klasifikasi susunan
bumi
> berdasarkan rheology dengan istilah2 klasifikasi susunan bumi berdasarkan
> komposisi mineral/kimiawi.
> (lihat Allen and Allen, 1990)
>
>
> ----- Original Message -----
> From: "Ade Kadarusman" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Thursday, September 11, 2003 2:55 AM
> Subject: Re: FW: [iagi-net-l] Re: korelasi geodinamik
>
>
> > Dear All,
> > Hanya sedikit koreksi untuk menghilangkan salah pengertian tentang
lapisan
> > Bumi.
> > Berdasarkan data seismik disepakati lapisan Bumi sebenarnya hanya ada
enam
> > (konsensus 10 tahun terakhir), yaitu Inner Core (solid), Outer Core
> > (liquid), Lower mantle (solid), Transition zone (solid), Upper mantle
> > (solid) dan
> > crust (oceanic dan continental crusts).
> > Mantel Atas (upper mantle) dibagi lagi menjadi:
> > -Lithosheric mantle (dari 80-200 km sampai 6-30 km, tepat dibawah Moho)
> > -Asthenosphere(dari 250 km sampai antara 80-200 km)
> > -Upper mantle (400-250 km)
> >
> > Jadi kalau dibilang lithosphere sebenarnya terdiri dari lithospheric
> mantle
> > dan
> > crust (oceanic/continental crust), sedangkan asthenosphere sering
dibilang
> > cair, sebenarnya tidak tepat, tetap solid (komposisinya ultrabasa),
tetapi
> > asthenosphere relatif lebih tidak solid dibandingkan lapisan lainnya di
> > upper mantle karena adanya proses partial melting, sehingga lempeng
> > lithosphere (mantle dan crust) bisa bergerak relatif terhadap
> asthenosphere,
> > karena adanya
> > bagian yang meleleh di asthenosphere.
> > Jadi analoginya bagian yang meleleh (melted part) di upper mantle jadi
> > pelicin
> > buat lempeng lithosphere untuk bergerak.
> >
> > hanya itu aja
> > Ade Kadarusman
> >
> >
> >
> > > Tujuh lapisan bumi : Core dalam (relatif padat), core luar (cair),
> mantel
> > > dalam (relatif padat), core luar (cair), asthenospher cair, lithosfer
> > > (padat), lempeng (padat). Hampir semua bersifat kemagnitan.
Perubahan
> > sudut
> > > palnet-planet-palnet terhadap bumi, menyebabkan merubah gaya gerak
masa
> > > didalam bumi. Bumi yang bergerak spiral, timbulkan lempeng
> > > (kontinenal-oseanik) yang berotasi.
> > >
> >
>
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