Mungkin kepanjangan, sehingga kami kirim kembali diperpendek (smoga gag dobel terkirim). Berapa kata terpanjang bisa terkirim ? MYT -----Original Message----- From: Maryanto Sent: Tuesday, September 30, 2003 11:03 Pagi To: '[EMAIL PROTECTED]' Subject: RE: FW: [iagi-net-l] Re: korelasi geodinamik
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 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. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] Visit IAGI Website: http://iagi.or.id IAGI-net Archive 1: http://www.mail-archive.com/iagi-net%40iagi.or.id/ IAGI-net Archive 2: http://groups.yahoo.com/group/iagi Komisi Sedimentologi (FOSI) : F. Hasan Sidi([EMAIL PROTECTED])-http://fosi.iagi.or.id Komisi SDM/Pendidikan : Edy Sunardi([EMAIL PROTECTED]) Komisi Karst : Hanang Samodra([EMAIL PROTECTED]) Komisi Sertifikasi : M. Suryowibowo([EMAIL PROTECTED]) Komisi OTODA : Ridwan Djamaluddin([EMAIL PROTECTED] atau [EMAIL PROTECTED]), Arif Zardi Dahlius([EMAIL PROTECTED]) Komisi Database Geologi : Aria A. Mulhadiono([EMAIL PROTECTED]) ---------------------------------------------------------------------
