Re: la terra è cava?
Inviato da hornet il 27/10/2006 11:46:16
Citazione:
Imaging the inside of the earth with seismic waves is similar to imaging an unborn baby with ultrasound. Waves move at different speeds based on density and elacticity. For example,
8,948 miles per hour in bedrock
4,474 miles per hour in glacial till
3,355 miles per hour or slower in soft sediment
There are 3,000 different stations around the world which have measured more than 86,000 earthquakes since 1964. ( Also see 45. Here are some local stations. ) Each event is recorded and archived automatically by many stations and with the exact time and distance between stations is known the speeds of the waves can be calculated. This system of open data sharing is important for world wide monitoring of nuclear tests as well. Using a system of linear equations, locations of seismic events are automaticly determined within minutes and are publicly released.
Analysis of quake travel times and amplitudes yields a three dimensional map of wave paths through the Earth. Traveling waves that move from a material of one density into a material of a different density will change direction according to Snell's Law, and seismic waves do change speed within the earth and follow curved paths.
The same data analyzed in different ways can reveal different things about the inner earth. For example, in December, 2003, Raffaella Montelli of Princeton University and colleagues mapped the locations of 32 moving mantle plumes.
Lamprecht's Hollow Planet Model
The first illustration under seismic tomography is taken from Jan Lamprecht's "A Feasibility study of possible Hollow Worlds." Lamprecht claims that a shell 800 to 1000 miles thick would not allow waves to be detected around the world as they currently are, but shows a hollow planet model that does.
Lamprecht on hollowplanets.com also cites some seismic puzzles that may be solved by the Hollow Earth theory, including tens of thousands of Earthquakes with epicenters deeper than 150 Km which should not exist because, due to the pressure and heat, below 150 Km there is no known material which will not flow. Another mystery addressed are waves which slow down instead of speeding up when passing through the denser--but more elastic(?)--core. Can over 30 years of collected seismic data be interpreted in another way, a way that permits a hollow earth? This does indeed seem unlikely, especially when you consider the richness of the data and the work of people like Montelli, but is it impossible?
marcuzzzo ha scritto:
la composizione e lo spessore dei vari strati della terra è stata studiata attraverso la misurazione di propagazione delle onde sismiche. Ad esempio già nel 1909 lo scienziato croato Mohorovicic si accorse che un'onda si propaga a velocità differente a secondo del mezzo in cui viaggia! notò infatti che le onde sismiche aumentavano la loro velocità a 40km nel sottosuolo,tra la crosta e il mantello.
Questa zona venne infatti chiamata discontinuità di Mohorovicic!.Se la terra fosse cava, come si propagherebbero queste ultime?
Imaging the inside of the earth with seismic waves is similar to imaging an unborn baby with ultrasound. Waves move at different speeds based on density and elacticity. For example,
8,948 miles per hour in bedrock
4,474 miles per hour in glacial till
3,355 miles per hour or slower in soft sediment
There are 3,000 different stations around the world which have measured more than 86,000 earthquakes since 1964. ( Also see 45. Here are some local stations. ) Each event is recorded and archived automatically by many stations and with the exact time and distance between stations is known the speeds of the waves can be calculated. This system of open data sharing is important for world wide monitoring of nuclear tests as well. Using a system of linear equations, locations of seismic events are automaticly determined within minutes and are publicly released.
Analysis of quake travel times and amplitudes yields a three dimensional map of wave paths through the Earth. Traveling waves that move from a material of one density into a material of a different density will change direction according to Snell's Law, and seismic waves do change speed within the earth and follow curved paths.
The same data analyzed in different ways can reveal different things about the inner earth. For example, in December, 2003, Raffaella Montelli of Princeton University and colleagues mapped the locations of 32 moving mantle plumes.
Lamprecht's Hollow Planet Model
The first illustration under seismic tomography is taken from Jan Lamprecht's "A Feasibility study of possible Hollow Worlds." Lamprecht claims that a shell 800 to 1000 miles thick would not allow waves to be detected around the world as they currently are, but shows a hollow planet model that does.
Lamprecht on hollowplanets.com also cites some seismic puzzles that may be solved by the Hollow Earth theory, including tens of thousands of Earthquakes with epicenters deeper than 150 Km which should not exist because, due to the pressure and heat, below 150 Km there is no known material which will not flow. Another mystery addressed are waves which slow down instead of speeding up when passing through the denser--but more elastic(?)--core. Can over 30 years of collected seismic data be interpreted in another way, a way that permits a hollow earth? This does indeed seem unlikely, especially when you consider the richness of the data and the work of people like Montelli, but is it impossible?
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